TCSH(1)                                                                TCSH(1)


       tcsh - C shell with file name completion and command line editing


       tcsh [-bcdefFimnqstvVxX] [-Dname[=value]] [arg ...]
       tcsh -l


       tcsh  is  an enhanced but completely compatible version of the Berkeley
       UNIX C shell, csh(1).  It is a command language interpreter usable both
       as an interactive login shell and a shell script command processor.  It
       includes a command-line editor  (see  The  command-line  editor),  pro-
       grammable  word  completion (see Completion and listing), spelling cor-
       rection (see Spelling correction), a  history  mechanism  (see  History
       substitution),  job  control  (see  Jobs) and a C-like syntax.  The NEW
       FEATURES section describes major  enhancements  of  tcsh  over  csh(1).
       Throughout  this  manual,  features  of  tcsh  not found in most csh(1)
       implementations (specifically, the 4.4BSD csh) are labeled with  ‘(+)’,
       and features which are present in csh(1) but not usually documented are
       labeled with ‘(u)’.

   Argument list processing
       If the first argument (argument 0) to the shell is ‘-’  then  it  is  a
       login shell.  A login shell can be also specified by invoking the shell
       with the -l flag as the only argument.

       The rest of the flag arguments are interpreted as follows:

       -b  Forces a ‘‘break’’ from  option  processing,  causing  any  further
           shell arguments to be treated as non-option arguments.  The remain-
           ing arguments will not be interpreted as shell options.   This  may
           be used to pass options to a shell script without confusion or pos-
           sible subterfuge.  The shell will not  run  a  set-user  ID  script
           without this option.

       -c  Commands  are  read  from  the  following  argument  (which must be
           present, and must be a single  argument),  stored  in  the  command
           shell  variable  for  reference, and executed.  Any remaining argu-
           ments are placed in the argv shell variable.

       -d  The shell loads the directory stack from  ~/.cshdirs  as  described
           under Startup and shutdown, whether or not it is a login shell. (+)

           Sets the environment variable name to value. (Domain/OS only) (+)

       -e  The shell exits if any invoked  command  terminates  abnormally  or
           yields a non-zero exit status.

       -f  The shell ignores ~/.tcshrc, and thus starts faster.

       -F  The  shell  uses  fork(2)  instead  of vfork(2) to spawn processes.
           (Convex/OS only) (+)

       -i  The shell is interactive and prompts for its top-level input,  even
           if it appears to not be a terminal.  Shells are interactive without
           this option if their inputs and outputs are terminals.

       -l  The shell is a login shell.  Applicable only if -l is the only flag

       -m  The  shell loads ~/.tcshrc even if it does not belong to the effec-
           tive user.  Newer versions of su(1) can pass -m to the shell. (+)

       -n  The shell parses commands but does not execute them.  This aids  in
           debugging shell scripts.

       -q  The shell accepts SIGQUIT (see Signal handling) and behaves when it
           is used under a debugger.  Job control is disabled. (u)

       -s  Command input is taken from the standard input.

       -t  The shell reads and executes a single line of input.  A ‘\’ may  be
           used  to  escape  the  newline at the end of this line and continue
           onto another line.

       -v  Sets the verbose shell variable, so that command  input  is  echoed
           after history substitution.

       -x  Sets  the  echo shell variable, so that commands are echoed immedi-
           ately before execution.

       -V  Sets the verbose shell variable even before executing ~/.tcshrc.

       -X  Is to -x as -V is to -v.

           Print a help message on the standard output and exit. (+)

           Print the version/platform/compilation options on the standard out-
           put  and  exit.   This information is also contained in the version
           shell variable. (+)

       After processing of flag arguments, if arguments remain but none of the
       -c,  -i,  -s,  or -t options were given, the first argument is taken as
       the name of a file of commands, or ‘‘script’’,  to  be  executed.   The
       shell opens this file and saves its name for possible resubstitution by
       ‘$0’.  Because many systems use either the standard version 6  or  ver-
       sion  7  shells whose shell scripts are not compatible with this shell,
       the shell uses such a ‘standard’ shell to execute a script whose  first
       character is not a ‘#’, i.e., that does not start with a comment.

       Remaining arguments are placed in the argv shell variable.

   Startup and shutdown
       A  login  shell  begins  by  executing  commands  from the system files
       /etc/csh.cshrc and /etc/csh.login.   It  then  executes  commands  from
       files  in  the  user’s  home  directory:  first  ~/.tcshrc  (+)  or, if
       ~/.tcshrc is not found, ~/.cshrc, then ~/.history (or the value of  the
       histfile shell variable), then ~/.login, and finally ~/.cshdirs (or the
       value of  the  dirsfile  shell  variable)  (+).   The  shell  may  read
       /etc/csh.login  before  instead  of  after /etc/csh.cshrc, and ~/.login
       before instead of after ~/.tcshrc or ~/.cshrc  and  ~/.history,  if  so
       compiled; see the version shell variable. (+)

       Non-login  shells read only /etc/csh.cshrc and ~/.tcshrc or ~/.cshrc on

       For examples of startup  files,  please  consult  http://tcshrc.source-

       Commands  like  stty(1)  and  tset(1),  which need be run only once per
       login, usually go in one’s ~/.login file.  Users who need  to  use  the
       same  set  of  files with both csh(1) and tcsh can have only a ~/.cshrc
       which checks for the existence of the tcsh shell variable (q.v.) before
       using  tcsh-specific  commands,  or  can  have  both  a  ~/.cshrc and a
       ~/.tcshrc which sources (see the builtin command) ~/.cshrc.   The  rest
       of  this manual uses ‘~/.tcshrc’ to mean ‘~/.tcshrc or, if ~/.tcshrc is
       not found, ~/.cshrc’.

       In the normal case, the shell begins reading commands from  the  termi-
       nal,  prompting with ‘> ’.  (Processing of arguments and the use of the
       shell to process files containing command scripts are described later.)
       The  shell  repeatedly  reads  a  line of command input, breaks it into
       words, places it on the command history list, parses  it  and  executes
       each command in the line.

       One can log out by typing ‘^D’ on an empty line, ‘logout’ or ‘login’ or
       via the shell’s autologout mechanism (see the  autologout  shell  vari-
       able).  When a login shell terminates it sets the logout shell variable
       to ‘normal’ or ‘automatic’ as appropriate, then executes commands  from
       the  files  /etc/csh.logout  and  ~/.logout.  The shell may drop DTR on
       logout if so compiled; see the version shell variable.

       The names of the system login and logout files vary from system to sys-
       tem for compatibility with different csh(1) variants; see FILES.

       We  first describe The command-line editor.  The Completion and listing
       and Spelling correction sections describe  two  sets  of  functionality
       that  are  implemented  as  editor commands but which deserve their own
       treatment.  Finally, Editor commands lists  and  describes  the  editor
       commands specific to the shell and their default bindings.

   The command-line editor (+)
       Command-line  input  can  be edited using key sequences much like those
       used in GNU Emacs or vi(1).  The editor is active only  when  the  edit
       shell  variable  is  set, which it is by default in interactive shells.
       The bindkey builtin can display and change key  bindings.   Emacs-style
       key  bindings are used by default (unless the shell was compiled other-
       wise; see the version shell variable), but bindkey can change  the  key
       bindings to vi-style bindings en masse.

       The  shell always binds the arrow keys (as defined in the TERMCAP envi-
       ronment variable) to

           down    down-history
           up      up-history
           left    backward-char
           right   forward-char

       unless doing so would alter another single-character binding.  One  can
       set  the  arrow  key escape sequences to the empty string with settc to
       prevent these bindings.  The ANSI/VT100 sequences for  arrow  keys  are
       always bound.

       Other  key  bindings are, for the most part, what Emacs and vi(1) users
       would expect and can easily be displayed by bindkey,  so  there  is  no
       need to list them here.  Likewise, bindkey can list the editor commands
       with a short description of each.

       Note that editor commands do not have the same notion of a ‘‘word’’  as
       does  the  shell.   The editor delimits words with any non-alphanumeric
       characters not in the shell variable wordchars, while the shell  recog-
       nizes  only whitespace and some of the characters with special meanings
       to it, listed under Lexical structure.

   Completion and listing (+)
       The shell is often able to complete words when given a unique abbrevia-
       tion.  Type part of a word (for example ‘ls /usr/lost’) and hit the tab
       key to run the complete-word editor command.  The shell  completes  the
       filename  ‘/usr/lost’  to  ‘/usr/lost+found/’, replacing the incomplete
       word with the complete word in the input buffer.   (Note  the  terminal
       ‘/’;  completion  adds  a ‘/’ to the end of completed directories and a
       space to the end of other completed words, to speed typing and  provide
       a  visual  indicator  of  successful  completion.   The addsuffix shell
       variable can be unset to prevent this.)  If no match is found  (perhaps
       ‘/usr/lost+found’ doesn’t exist), the terminal bell rings.  If the word
       is already complete (perhaps there is a ‘/usr/lost’ on your system,  or
       perhaps  you  were  thinking too far ahead and typed the whole thing) a
       ‘/’ or space is added to the end if it isn’t already there.

       Completion works anywhere in the line, not at just the  end;  completed
       text  pushes the rest of the line to the right.  Completion in the mid-
       dle of a word often results in leftover characters to the right of  the
       cursor that need to be deleted.

       Commands  and  variables  can  be  completed in much the same way.  For
       example, typing ‘em[tab]’ would complete ‘em’ to ‘emacs’ if emacs  were
       the  only  command  on your system beginning with ‘em’.  Completion can
       find a command in any directory in path or if given  a  full  pathname.
       Typing  ‘echo  $ar[tab]’  would  complete  ‘$ar’ to ‘$argv’ if no other
       variable began with ‘ar’.

       The shell parses the input buffer to determine  whether  the  word  you
       want  to  complete  should be completed as a filename, command or vari-
       able.  The first word in the buffer and the first word  following  ‘;’,
       ‘|’,  ‘|&’,  ‘&&’ or ‘||’ is considered to be a command.  A word begin-
       ning with ‘$’ is considered to be a variable.  Anything else is a file-
       name.  An empty line is ‘completed’ as a filename.

       You  can  list the possible completions of a word at any time by typing
       ‘^D’ to run the delete-char-or-list-or-eof editor command.   The  shell
       lists  the  possible  completions  using  the  ls-F builtin (q.v.)  and
       reprints the prompt and unfinished command line, for example:

           > ls /usr/l[^D]
           lbin/       lib/        local/      lost+found/
           > ls /usr/l

       If the autolist shell variable is set, the shell  lists  the  remaining
       choices (if any) whenever completion fails:

           > set autolist
           > nm /usr/lib/libt[tab]
           libtermcap.a@ libtermlib.a@
           > nm /usr/lib/libterm

       If autolist is set to ‘ambiguous’, choices are listed only when comple-
       tion fails and adds no new characters to the word being completed.

       A filename to be completed can contain variables, your own  or  others’
       home  directories  abbreviated with ‘~’ (see Filename substitution) and
       directory stack entries abbreviated with ‘=’ (see Directory stack  sub-
       stitution).  For example,

           > ls ~k[^D]
           kahn    kas     kellogg
           > ls ~ke[tab]
           > ls ~kellogg/


           > set local = /usr/local
           > ls $lo[tab]
           > ls $local/[^D]
           bin/ etc/ lib/ man/ src/
           > ls $local/

       Note  that  variables  can also be expanded explicitly with the expand-
       variables editor command.

       delete-char-or-list-or-eof lists at only the end of the  line;  in  the
       middle  of  a  line it deletes the character under the cursor and on an
       empty line it logs one out or,  if  ignoreeof  is  set,  does  nothing.
       ‘M-^D’, bound to the editor command list-choices, lists completion pos-
       sibilities anywhere on a line, and list-choices  (or  any  one  of  the
       related  editor  commands that do or don’t delete, list and/or log out,
       listed under delete-char-or-list-or-eof) can be bound to ‘^D’ with  the
       bindkey builtin command if so desired.

       The complete-word-fwd and complete-word-back editor commands (not bound
       to any keys by default) can be used to cycle up and  down  through  the
       list  of possible completions, replacing the current word with the next
       or previous word in the list.

       The shell variable fignore can be set to  a  list  of  suffixes  to  be
       ignored by completion.  Consider the following:

           > ls
           Makefile        condiments.h~   main.o          side.c
           README          main.c          meal            side.o
           condiments.h    main.c~
           > set fignore = (.o \~)
           > emacs ma[^D]
           main.c   main.c~  main.o
           > emacs ma[tab]
           > emacs main.c

       ‘main.c~’  and  ‘main.o’  are  ignored by completion (but not listing),
       because they end in suffixes in fignore.  Note that a ‘\’ was needed in
       front  of  ‘~’  to  prevent it from being expanded to home as described
       under Filename substitution.  fignore is ignored if only one completion
       is possible.

       If  the  complete  shell  variable  is  set to ‘enhance’, completion 1)
       ignores case and 2) considers periods, hyphens  and  underscores  (‘.’,
       ‘-’  and  ‘_’)  to be word separators and hyphens and underscores to be
       equivalent.  If you had the following files

           comp.lang.c      comp.lang.perl   comp.std.c++
           comp.lang.c++    comp.std.c

       and typed ‘mail -f c.l.c[tab]’, it  would  be  completed  to  ‘mail  -f
       comp.lang.c’,  and  ^D  would  list  ‘comp.lang.c’ and ‘comp.lang.c++’.
       ‘mail -f c..c++[^D]’ would  list  ‘comp.lang.c++’  and  ‘comp.std.c++’.
       Typing ‘rm a--file[^D]’ in the following directory

           A_silly_file    a-hyphenated-file    another_silly_file

       would  list  all  three  files, because case is ignored and hyphens and
       underscores are equivalent.  Periods, however, are  not  equivalent  to
       hyphens or underscores.

       Completion  and  listing are affected by several other shell variables:
       recexact can be set to complete on the shortest possible unique  match,
       even if more typing might result in a longer match:

           > ls
           fodder   foo      food     foonly
           > set recexact
           > rm fo[tab]

       just beeps, because ‘fo’ could expand to ‘fod’ or ‘foo’, but if we type
       another ‘o’,

           > rm foo[tab]
           > rm foo

       the completion completes on ‘foo’, even though ‘food’ and ‘foonly’ also
       match.   autoexpand can be set to run the expand-history editor command
       before each completion attempt, autocorrect can be set to spelling-cor-
       rect  the  word  to  be completed (see Spelling correction) before each
       completion attempt and correct can be set to complete commands automat-
       ically  after  one hits ‘return’.  matchbeep can be set to make comple-
       tion beep or not beep in a variety of situations, and nobeep can be set
       to  never  beep  at  all.   nostat  can be set to a list of directories
       and/or patterns that match directories to prevent the completion mecha-
       nism from stat(2)ing those directories.  listmax and listmaxrows can be
       set to limit the number of  items  and  rows  (respectively)  that  are
       listed  without asking first.  recognize_only_executables can be set to
       make the shell list only executables when listing commands, but  it  is
       quite slow.

       Finally, the complete builtin command can be used to tell the shell how
       to complete words other than filenames, commands and  variables.   Com-
       pletion  and listing do not work on glob-patterns (see Filename substi-
       tution), but the list-glob  and  expand-glob  editor  commands  perform
       equivalent functions for glob-patterns.

   Spelling correction (+)
       The shell can sometimes correct the spelling of filenames, commands and
       variable names as well as completing and listing them.

       Individual words can be spelling-corrected with the  spell-word  editor
       command (usually bound to M-s and M-S) and the entire input buffer with
       spell-line (usually bound to M-$).  The correct shell variable  can  be
       set to ‘cmd’ to correct the command name or ‘all’ to correct the entire
       line each time return is typed, and autocorrect can be set  to  correct
       the word to be completed before each completion attempt.

       When  spelling correction is invoked in any of these ways and the shell
       thinks that any part of the command line is misspelled, it prompts with
       the corrected line:

           > set correct = cmd
           > lz /usr/bin
           CORRECT>ls /usr/bin (y|n|e|a)?

       One can answer ‘y’ or space to execute the corrected line, ‘e’ to leave
       the uncorrected command in the input buffer, ‘a’ to abort  the  command
       as if ‘^C’ had been hit, and anything else to execute the original line

       Spelling correction recognizes user-defined completions (see  the  com-
       plete  builtin  command).   If  an input word in a position for which a
       completion is defined resembles a word in the completion list, spelling
       correction  registers  a  misspelling and suggests the latter word as a
       correction.  However, if the input word does not match any of the  pos-
       sible  completions for that position, spelling correction does not reg-
       ister a misspelling.

       Like completion, spelling correction works anywhere in the line,  push-
       ing  the rest of the line to the right and possibly leaving extra char-
       acters to the right of the cursor.

       Beware: spelling correction is not  guaranteed  to  work  the  way  one
       intends,  and  is  provided mostly as an experimental feature.  Sugges-
       tions and improvements are welcome.

   Editor commands (+)
       ‘bindkey’ lists  key  bindings  and  ‘bindkey  -l’  lists  and  briefly
       describes  editor  commands.  Only new or especially interesting editor
       commands are described here.  See emacs(1) and vi(1)  for  descriptions
       of each editor’s key bindings.

       The  character  or characters to which each command is bound by default
       is given in parentheses.  ‘^character’ means a  control  character  and
       ‘M-character’  a meta character, typed as escape-character on terminals
       without a meta key.  Case counts, but commands that are bound  to  let-
       ters by default are bound to both lower- and uppercase letters for con-

       complete-word (tab)
               Completes a word as described under Completion and listing.

       complete-word-back (not bound)
               Like complete-word-fwd, but steps up from the end of the  list.

       complete-word-fwd (not bound)
               Replaces  the  current  word with the first word in the list of
               possible completions.  May be repeated to step down through the
               list.   At the end of the list, beeps and reverts to the incom-
               plete word.

       complete-word-raw (^X-tab)
               Like complete-word, but ignores user-defined completions.

       copy-prev-word (M-^_)
               Copies the previous word in the current  line  into  the  input
               buffer.  See also insert-last-word.

       dabbrev-expand (M-/)
               Expands  the  current word to the most recent preceding one for
               which the current is a leading substring, wrapping  around  the
               history  list  (once)  if  necessary.  Repeating dabbrev-expand
               without any intervening typing changes  to  the  next  previous
               word etc., skipping identical matches much like history-search-
               backward does.

       delete-char (not bound)
               Deletes the character under the cursor.  See also  delete-char-

       delete-char-or-eof (not bound)
               Does  delete-char  if  there is a character under the cursor or
               end-of-file on an empty line.  See also delete-char-or-list-or-

       delete-char-or-list (not bound)
               Does  delete-char  if  there is a character under the cursor or
               list-choices at the end of the line.  See also  delete-char-or-

       delete-char-or-list-or-eof (^D)
               Does  delete-char  if  there  is  a character under the cursor,
               list-choices at the end of the line or end-of-file on an  empty
               line.  See also those three commands, each of which does only a
               single action, and delete-char-or-eof, delete-char-or-list  and
               list-or-eof,  each  of  which  does  a different two out of the

       down-history (down-arrow, ^N)
               Like up-history, but steps down, stopping at the original input

       end-of-file (not bound)
               Signals  an  end  of file, causing the shell to exit unless the
               ignoreeof shell variable (q.v.) is set to  prevent  this.   See
               also delete-char-or-list-or-eof.

       expand-history (M-space)
               Expands history substitutions in the current word.  See History
               substitution.  See also magic-space, toggle-literal-history and
               the autoexpand shell variable.

       expand-glob (^X-*)
               Expands  the glob-pattern to the left of the cursor.  See File-
               name substitution.

       expand-line (not bound)
               Like expand-history, but expands history substitutions in  each
               word in the input buffer,

       expand-variables (^X-$)
               Expands  the  variable to the left of the cursor.  See Variable

       history-search-backward (M-p, M-P)
               Searches backwards through  the  history  list  for  a  command
               beginning  with  the current contents of the input buffer up to
               the cursor and copies it into the  input  buffer.   The  search
               string  may  be a glob-pattern (see Filename substitution) con-
               taining ‘*’, ‘?’, ‘[]’ or ‘{}’.   up-history  and  down-history
               will  proceed  from  the appropriate point in the history list.
               Emacs mode only.  See also history-search-forward and i-search-

       history-search-forward (M-n, M-N)
               Like history-search-backward, but searches forward.

       i-search-back (not bound)
               Searches  backward  like  history-search-backward,  copies  the
               first match into the input buffer with the cursor positioned at
               the  end of the pattern, and prompts with ‘bck: ’ and the first
               match.  Additional  characters  may  be  typed  to  extend  the
               search,  i-search-back  may be typed to continue searching with
               the same pattern, wrapping around the history  list  if  neces-
               sary,  (i-search-back  must  be bound to a single character for
               this to work) or one of the following special characters may be

                   ^W      Appends  the  rest  of the word under the cursor to
                           the search pattern.
                   delete (or any character bound to backward-delete-char)
                           Undoes the effect of the last character  typed  and
                           deletes  a  character  from  the  search pattern if
                   ^G      If the previous search was successful,  aborts  the
                           entire  search.  If not, goes back to the last suc-
                           cessful search.
                   escape  Ends the search, leaving the current  line  in  the
                           input buffer.

               Any other character not bound to self-insert-command terminates
               the search, leaving the current line in the input  buffer,  and
               is then interpreted as normal input.  In particular, a carriage
               return causes the current line  to  be  executed.   Emacs  mode
               only.  See also i-search-fwd and history-search-backward.

       i-search-fwd (not bound)
               Like i-search-back, but searches forward.

       insert-last-word (M-_)
               Inserts  the  last  word of the previous input line (‘!$’) into
               the input buffer.  See also copy-prev-word.

       list-choices (M-^D)
               Lists completion possibilities as  described  under  Completion
               and  listing.   See  also  delete-char-or-list-or-eof and list-

       list-choices-raw (^X-^D)
               Like list-choices, but ignores user-defined completions.

       list-glob (^X-g, ^X-G)
               Lists (via the ls-F builtin) matches to the  glob-pattern  (see
               Filename substitution) to the left of the cursor.

       list-or-eof (not bound)
               Does  list-choices  or  end-of-file on an empty line.  See also

       magic-space (not bound)
               Expands history substitutions in the current line, like expand-
               history,  and  inserts  a space.  magic-space is designed to be
               bound to the space bar, but is not bound by default.

       normalize-command (^X-?)
               Searches for the current word in PATH  and,  if  it  is  found,
               replaces  it  with  the  full  path to the executable.  Special
               characters are quoted.  Aliases are  expanded  and  quoted  but
               commands  within  aliases are not.  This command is useful with
               commands that take commands as arguments, e.g., ‘dbx’  and  ‘sh

       normalize-path (^X-n, ^X-N)
               Expands  the  current word as described under the ‘expand’ set-
               ting of the symlinks shell variable.

       overwrite-mode (unbound)
               Toggles between input and overwrite modes.

       run-fg-editor (M-^Z)
               Saves the current input line and looks for a stopped job with a
               name  equal  to the last component of the file name part of the
               EDITOR or VISUAL environment variables, or, if neither is  set,
               ‘ed’  or  ‘vi’.   If such a job is found, it is restarted as if
               ‘fg %job’ had been typed.  This is  used  to  toggle  back  and
               forth between an editor and the shell easily.  Some people bind
               this command to ‘^Z’ so they can do this even more easily.

       run-help (M-h, M-H)
               Searches for documentation on the current  command,  using  the
               same  notion  of  ‘current command’ as the completion routines,
               and prints it.  There is no way to use  a  pager;  run-help  is
               designed  for  short help files.  If the special alias helpcom-
               mand is defined, it is run with the  command  name  as  a  sole
               argument.   Else,  documentation should be in a file named com-
               mand.help, command.1, command.6, command.8  or  command,  which
               should  be  in one of the directories listed in the HPATH envi-
               ronment variable.  If there is more than one help file only the
               first is printed.

       self-insert-command (text characters)
               In  insert mode (the default), inserts the typed character into
               the input line after the character under the cursor.  In  over-
               write  mode,  replaces  the character under the cursor with the
               typed character.  The input mode is normally preserved  between
               lines,  but the inputmode shell variable can be set to ‘insert’
               or ‘overwrite’ to put the editor in that mode at the  beginning
               of each line.  See also overwrite-mode.

       sequence-lead-in (arrow prefix, meta prefix, ^X)
               Indicates that the following characters are part of a multi-key
               sequence.  Binding a command to  a  multi-key  sequence  really
               creates  two  bindings: the first character to sequence-lead-in
               and the whole sequence to the command.  All sequences beginning
               with  a  character  bound  to  sequence-lead-in are effectively
               bound to undefined-key unless bound to another command.

       spell-line (M-$)
               Attempts to correct the spelling of  each  word  in  the  input
               buffer,  like spell-word, but ignores words whose first charac-
               ter is one of ‘-’, ‘!’, ‘^’ or ‘%’, or which contain  ‘\’,  ‘*’
               or  ‘?’, to avoid problems with switches, substitutions and the
               like.  See Spelling correction.

       spell-word (M-s, M-S)
               Attempts to  correct  the  spelling  of  the  current  word  as
               described  under Spelling correction.  Checks each component of
               a word which appears to be a pathname.

       toggle-literal-history (M-r, M-R)
               Expands or  ‘unexpands’  history  substitutions  in  the  input
               buffer.  See also expand-history and the autoexpand shell vari-

       undefined-key (any unbound key)

       up-history (up-arrow, ^P)
               Copies the previous entry in the history list  into  the  input
               buffer.  If histlit is set, uses the literal form of the entry.
               May be repeated to step up through the history  list,  stopping
               at the top.

       vi-search-back (?)
               Prompts  with ‘?’ for a search string (which may be a glob-pat-
               tern, as with history-search-backward),  searches  for  it  and
               copies it into the input buffer.  The bell rings if no match is
               found.  Hitting return ends the  search  and  leaves  the  last
               match  in the input buffer.  Hitting escape ends the search and
               executes the match.  vi mode only.

       vi-search-fwd (/)
               Like vi-search-back, but searches forward.

       which-command (M-?)
               Does a which (see the description of the  builtin  command)  on
               the first word of the input buffer.

       yank-pop (M-y)
               When  executed  immediately  after  a yank or another yank-pop,
               replaces the yanked string with the next previous  string  from
               the  killring.  This  also has the effect of rotating the kill-
               ring, such  that  this  string  will  be  considered  the  most
               recently  killed  by  a  later yank command. Repeating yank-pop
               will cycle through the killring any number of times.

   Lexical structure
       The shell splits input lines into words at blanks and tabs.   The  spe-
       cial  characters  ‘&’, ‘|’, ‘;’, ‘<’, ‘>’, ‘(’, and ‘)’ and the doubled
       characters ‘&&’, ‘||’, ‘<<’ and ‘>>’ are always separate words, whether
       or not they are surrounded by whitespace.

       When the shell’s input is not a terminal, the character ‘#’ is taken to
       begin a comment.  Each ‘#’ and the rest of the input line on  which  it
       appears is discarded before further parsing.

       A  special  character  (including a blank or tab) may be prevented from
       having its special meaning, and possibly made part of another word,  by
       preceding  it  with  a backslash (‘\’) or enclosing it in single (‘’’),
       double (‘"’) or backward (‘‘’) quotes.  When  not  otherwise  quoted  a
       newline  preceded  by a ‘\’ is equivalent to a blank, but inside quotes
       this sequence results in a newline.

       Furthermore, all Substitutions (see below) except History  substitution
       can  be  prevented  by  enclosing  the strings (or parts of strings) in
       which they appear with single quotes or by quoting the crucial  charac-
       ter(s) (e.g., ‘$’ or ‘‘’ for Variable substitution or Command substitu-
       tion respectively) with ‘\’.   (Alias  substitution  is  no  exception:
       quoting  in any way any character of a word for which an alias has been
       defined prevents substitution of the alias.  The usual way  of  quoting
       an  alias  is  to precede it with a backslash.) History substitution is
       prevented by backslashes but not by single quotes.  Strings quoted with
       double  or  backward  quotes  undergo Variable substitution and Command
       substitution, but other substitutions are prevented.

       Text inside single or double quotes becomes a single word (or  part  of
       one).   Metacharacters  in these strings, including blanks and tabs, do
       not form separate words.  Only in one special case (see Command substi-
       tution  below)  can a double-quoted string yield parts of more than one
       word; single-quoted strings never do.   Backward  quotes  are  special:
       they  signal Command substitution (q.v.), which may result in more than
       one word.

       Quoting complex strings, particularly strings which themselves  contain
       quoting characters, can be confusing.  Remember that quotes need not be
       used as they are in human writing!  It may be easier to  quote  not  an
       entire  string,  but only those parts of the string which need quoting,
       using different types of quoting to do so if appropriate.

       The backslash_quote shell variable (q.v.) can  be  set  to  make  back-
       slashes  always  quote  ‘\’,  ‘’’,  and ‘"’.  (+) This may make complex
       quoting tasks easier, but it can cause syntax errors in csh(1) scripts.

       We  now  describe the various transformations the shell performs on the
       input in the order in which they occur.  We note in  passing  the  data
       structures  involved  and the commands and variables which affect them.
       Remember that substitutions can be prevented by  quoting  as  described
       under Lexical structure.

   History substitution
       Each  command,  or  ‘‘event’’,  input from the terminal is saved in the
       history list.  The previous command is always saved,  and  the  history
       shell  variable can be set to a number to save that many commands.  The
       histdup shell variable can be set to not save duplicate events or  con-
       secutive duplicate events.

       Saved  commands  are  numbered sequentially from 1 and stamped with the
       time.  It is not usually necessary to use event numbers, but  the  cur-
       rent  event  number can be made part of the prompt by placing an ‘!’ in
       the prompt shell variable.

       The shell actually saves history in expanded and  literal  (unexpanded)
       forms.  If the histlit shell variable is set, commands that display and
       store history use the literal form.

       The history builtin command can print, store in  a  file,  restore  and
       clear the history list at any time, and the savehist and histfile shell
       variables can be can be set to store the history list automatically  on
       logout and restore it on login.

       History  substitutions  introduce  words from the history list into the
       input stream, making it easy to repeat commands, repeat arguments of  a
       previous  command  in  the current command, or fix spelling mistakes in
       the previous command with little typing and a  high  degree  of  confi-

       History  substitutions  begin  with  the character ‘!’.  They may begin
       anywhere in the input stream, but they do not nest.   The  ‘!’  may  be
       preceded  by  a  ‘\’ to prevent its special meaning; for convenience, a
       ‘!’ is passed unchanged when it is followed by a blank,  tab,  newline,
       ‘=’ or ‘(’.  History substitutions also occur when an input line begins
       with ‘^’.  This special abbreviation  will  be  described  later.   The
       characters  used  to  signal  history substitution (‘!’ and ‘^’) can be
       changed by setting the histchars shell variable.  Any input line  which
       contains a history substitution is printed before it is executed.

       A history substitution may have an ‘‘event specification’’, which indi-
       cates the event from which words are to be  taken,  a  ‘‘word  designa-
       tor’’,  which  selects particular words from the chosen event, and/or a
       ‘‘modifier’’, which manipulates the selected words.

       An event specification can be

           n       A number, referring to a particular event
           -n      An offset, referring to the  event  n  before  the  current
           #       The  current  event.   This  should  be  used  carefully in
                   csh(1), where there is no check for recursion.  tcsh allows
                   10 levels of recursion.  (+)
           !       The previous event (equivalent to ‘-1’)
           s       The  most  recent  event  whose  first word begins with the
                   string s
           ?s?     The most recent event which contains  the  string  s.   The
                   second  ‘?’ can be omitted if it is immediately followed by
                   a newline.

       For example, consider this bit of someone’s history list:

            9  8:30    nroff -man wumpus.man
           10  8:31    cp wumpus.man wumpus.man.old
           11  8:36    vi wumpus.man
           12  8:37    diff wumpus.man.old wumpus.man

       The commands are shown with their event numbers and time  stamps.   The
       current  event,  which we haven’t typed in yet, is event 13.  ‘!11’ and
       ‘!-2’ refer to event 11.  ‘!!’ refers to the previous event, 12.   ‘!!’
       can  be  abbreviated  ‘!’  if  it  is followed by ‘:’ (‘:’ is described
       below).  ‘!n’ refers to event 9, which begins with ‘n’.  ‘!?old?’  also
       refers  to event 12, which contains ‘old’.  Without word designators or
       modifiers history references simply expand to the entire event,  so  we
       might  type  ‘!cp’  to redo the copy command or ‘!!|more’ if the ‘diff’
       output scrolled off the top of the screen.

       History references may be insulated  from  the  surrounding  text  with
       braces  if  necessary.   For  example, ‘!vdoc’ would look for a command
       beginning with  ‘vdoc’,  and,  in  this  example,  not  find  one,  but
       ‘!{v}doc’  would  expand  unambiguously to ‘vi wumpus.mandoc’.  Even in
       braces, history substitutions do not nest.

       (+) While csh(1) expands, for example, ‘!3d’ to event 3 with the letter
       ‘d’  appended  to  it, tcsh expands it to the last event beginning with
       ‘3d’; only completely numeric arguments are treated as  event  numbers.
       This  makes  it  possible  to recall events beginning with numbers.  To
       expand ‘!3d’ as in csh(1) say ‘!\3d’.

       To select words from an event we can follow the event specification  by
       a  ‘:’  and  a designator for the desired words.  The words of an input
       line are numbered from 0, the first (usually command) word being 0, the
       second  word (first argument) being 1, etc.  The basic word designators

           0       The first (command) word
           n       The nth argument
           ^       The first argument, equivalent to ‘1’
           $       The last argument
           %       The word matched by an ?s? search
           x-y     A range of words
           -y      Equivalent to 0-y
           *       Equivalent to ‘^-$’, but returns nothing if the event  con-
                   tains only 1 word
           x*      Equivalent to x-$
           x-      Equivalent to x*, but omitting the last word (‘$’)

       Selected  words  are inserted into the command line separated by single
       blanks.  For example, the ‘diff’ command in the previous example  might
       have been typed as ‘diff !!:1.old !!:1’ (using ‘:1’ to select the first
       argument from the previous event) or ‘diff !-2:2 !-2:1’ to  select  and
       swap  the arguments from the ‘cp’ command.  If we didn’t care about the
       order of the ‘diff’ we might have said ‘diff !-2:1-2’ or  simply  ‘diff
       !-2:*’.   The  ‘cp’  command  might  have  been  written ‘cp wumpus.man
       !#:1.old’, using ‘#’ to refer to the current event.  ‘!n:-  hurkle.man’
       would  reuse the first two words from the ‘nroff’ command to say ‘nroff
       -man hurkle.man’.

       The ‘:’ separating the event specification from the word designator can
       be omitted if the argument selector begins with a ‘^’, ‘$’, ‘*’, ‘%’ or
       ‘-’.  For example, our ‘diff’ command might  have  been  ‘diff  !!^.old
       !!^’  or, equivalently, ‘diff !!$.old !!$’.  However, if ‘!!’ is abbre-
       viated ‘!’, an argument selector beginning with ‘-’ will be interpreted
       as an event specification.

       A  history reference may have a word designator but no event specifica-
       tion.  It then references the previous command.  Continuing our  ‘diff’
       example,  we  could  have  said  simply ‘diff !^.old !^’ or, to get the
       arguments in the opposite order, just ‘diff !*’.

       The word or words in a history reference  can  be  edited,  or  ‘‘modi-
       fied’’,  by following it with one or more modifiers, each preceded by a

           h       Remove a trailing pathname component, leaving the head.
           t       Remove all leading pathname components, leaving the tail.
           r       Remove a filename extension ‘.xxx’, leaving the root  name.
           e       Remove all but the extension.
           u       Uppercase the first lowercase letter.
           l       Lowercase the first uppercase letter.
           s/l/r/  Substitute  l  for  r.   l is simply a string like r, not a
                   regular expression as in the eponymous ed(1) command.   Any
                   character  may  be used as the delimiter in place of ‘/’; a
                   ‘\’ can be used to quote the delimiter inside l and r.  The
                   character  ‘&’  in  the r is replaced by l; ‘\’ also quotes
                   ‘&’.  If l is empty (‘‘’’), the l from a previous substitu-
                   tion  or the s from a previous ‘?s?’ event specification is
                   used.  The trailing delimiter may be omitted if it is imme-
                   diately followed by a newline.
           &       Repeat the previous substitution.
           g       Apply the following modifier once to each word.
           a (+)   Apply the following modifier as many times as possible to a
                   single word.  ‘a’ and ‘g’ can be used together to  apply  a
                   modifier  globally.   In  the current implementation, using
                   the ‘a’ and ‘s’ modifiers together can lead to an  infinite
                   loop.  For example, ‘:as/f/ff/’ will never terminate.  This
                   behavior might change in the future.
           p       Print the new command line but do not execute it.
           q       Quote the substituted words, preventing  further  substitu-
           x       Like  q, but break into words at blanks, tabs and newlines.

       Modifiers are applied to only the first modifiable word (unless ‘g’  is
       used).  It is an error for no word to be modifiable.

       For  example,  the ‘diff’ command might have been written as ‘diff wum-
       pus.man.old !#^:r’, using ‘:r’ to remove ‘.old’ from the first argument
       on  the  same  line (‘!#^’).  We could say ‘echo hello out there’, then
       ‘echo !*:u’ to capitalize ‘hello’, ‘echo !*:au’ to say it out loud,  or
       ‘echo  !*:agu’  to really shout.  We might follow ‘mail -s "I forgot my
       password" rot’ with ‘!:s/rot/root’ to correct the  spelling  of  ‘root’
       (but see Spelling correction for a different approach).

       There is a special abbreviation for substitutions.  ‘^’, when it is the
       first character on an input line, is equivalent  to  ‘!:s^’.   Thus  we
       might have said ‘^rot^root’ to make the spelling correction in the pre-
       vious example.  This is the only history substitution  which  does  not
       explicitly begin with ‘!’.

       (+) In csh as such, only one modifier may be applied to each history or
       variable expansion.  In tcsh, more than one may be used, for example

           % mv wumpus.man /usr/man/man1/wumpus.1
           % man !$:t:r
           man wumpus

       In csh, the result would be ‘wumpus.1:r’.  A substitution followed by a
       colon may need to be insulated from it with braces:

           > mv a.out /usr/games/wumpus
           > setenv PATH !$:h:$PATH
           Bad ! modifier: $.
           > setenv PATH !{-2$:h}:$PATH
           setenv PATH /usr/games:/bin:/usr/bin:.

       The  first attempt would succeed in csh but fails in tcsh, because tcsh
       expects another modifier after the second colon rather than ‘$’.

       Finally, history can be accessed through the editor as well as  through
       the  substitutions  just described.  The up- and down-history, history-
       search-backward and -forward, i-search-back  and  -fwd,  vi-search-back
       and  -fwd,  copy-prev-word  and insert-last-word editor commands search
       for events in the history list and copy them  into  the  input  buffer.
       The toggle-literal-history editor command switches between the expanded
       and literal forms of history lines in the input buffer.  expand-history
       and expand-line expand history substitutions in the current word and in
       the entire input buffer respectively.

   Alias substitution
       The shell maintains a list of aliases  which  can  be  set,  unset  and
       printed  by  the  alias  and unalias commands.  After a command line is
       parsed into simple commands (see Commands) the first word of each  com-
       mand,  left-to-right, is checked to see if it has an alias.  If so, the
       first word is replaced by the alias.  If the alias contains  a  history
       reference, it undergoes History substitution (q.v.) as though the orig-
       inal command were the previous input line.  If the alias does not  con-
       tain a history reference, the argument list is left untouched.

       Thus  if  the  alias  for ‘ls’ were ‘ls -l’ the command ‘ls /usr’ would
       become ‘ls -l /usr’, the argument list here being undisturbed.  If  the
       alias  for ‘lookup’ were ‘grep !^ /etc/passwd’ then ‘lookup bill’ would
       become ‘grep bill /etc/passwd’.   Aliases  can  be  used  to  introduce
       parser metasyntax.  For example, ‘alias print ’pr \!* | lpr’’ defines a
       ‘‘command’’ (‘print’) which pr(1)s its arguments to the line printer.

       Alias substitution is repeated until the first word of the command  has
       no  alias.  If an alias substitution does not change the first word (as
       in the previous example) it is flagged to prevent a loop.  Other  loops
       are detected and cause an error.

       Some aliases are referred to by the shell; see Special aliases.

   Variable substitution
       The  shell  maintains a list of variables, each of which has as value a
       list of zero or more words.  The values of shell variables can be  dis-
       played  and  changed with the set and unset commands.  The system main-
       tains its own list of ‘‘environment’’ variables.   These  can  be  dis-
       played and changed with printenv, setenv and unsetenv.

       (+)  Variables  may  be  made read-only with ‘set -r’ (q.v.)  Read-only
       variables may not be modified or unset; attempting to do so will  cause
       an  error.  Once made read-only, a variable cannot be made writable, so
       ‘set -r’ should be used with caution.  Environment variables cannot  be
       made read-only.

       Some  variables  are  set  by  the  shell  or  referred  to by it.  For
       instance, the argv variable is an image of the shell’s  argument  list,
       and  words  of  this  variable’s value are referred to in special ways.
       Some of the variables referred to by the shell are toggles;  the  shell
       does  not  care  what their value is, only whether they are set or not.
       For instance, the verbose variable is a  toggle  which  causes  command
       input  to  be  echoed.   The -v command line option sets this variable.
       Special shell variables lists all variables which are  referred  to  by
       the shell.

       Other  operations treat variables numerically.  The ‘@’ command permits
       numeric calculations to be performed and the result assigned to a vari-
       able.   Variable  values  are,  however, always represented as (zero or
       more) strings.  For the purposes of numeric operations, the null string
       is considered to be zero, and the second and subsequent words of multi-
       word values are ignored.

       After the input line is aliased and parsed, and before each command  is
       executed,  variable  substitution is performed keyed by ‘$’ characters.
       This expansion can be prevented by preceding the ‘$’ with a ‘\’  except
       within  ‘"’s  where  it  always  occurs, and within ‘’’s where it never
       occurs.  Strings quoted by ‘‘’ are interpreted later (see Command  sub-
       stitution  below) so ‘$’ substitution does not occur there until later,
       if at all.  A ‘$’ is passed unchanged if followed by a blank,  tab,  or

       Input/output redirections are recognized before variable expansion, and
       are variable expanded separately.   Otherwise,  the  command  name  and
       entire  argument  list  are expanded together.  It is thus possible for
       the first (command) word (to this point)  to  generate  more  than  one
       word,  the  first  of  which  becomes the command name, and the rest of
       which become arguments.

       Unless enclosed in ‘"’ or given the ‘:q’ modifier the results of  vari-
       able  substitution  may eventually be command and filename substituted.
       Within ‘"’, a variable whose value consists of multiple  words  expands
       to a (portion of a) single word, with the words of the variable’s value
       separated by blanks.  When the ‘:q’ modifier is applied to a  substitu-
       tion  the  variable  will expand to multiple words with each word sepa-
       rated by a blank and quoted to prevent later command or  filename  sub-

       The  following metasequences are provided for introducing variable val-
       ues into the shell input.  Except as noted, it is an error to reference
       a variable which is not set.

       ${name} Substitutes the words of the value of variable name, each sepa-
               rated by a blank.  Braces insulate name from following  charac-
               ters which would otherwise be part of it.  Shell variables have
               names consisting of up to 20 letters and digits starting with a
               letter.   The  underscore character is considered a letter.  If
               name is not a shell variable, but is set  in  the  environment,
               then  that  value  is returned (but ‘:’ modifiers and the other
               forms given below are not available in this case).
               Substitutes only the selected words from  the  value  of  name.
               The  selector  is subjected to ‘$’ substitution and may consist
               of a single number or two numbers  separated  by  a  ‘-’.   The
               first word of a variable’s value is numbered ‘1’.  If the first
               number of a range is omitted it defaults to ‘1’.  If  the  last
               member  of  a  range  is  omitted it defaults to ‘$#name’.  The
               selector ‘*’ selects all words.  It is not an error for a range
               to be empty if the second argument is omitted or in range.
       $0      Substitutes  the  name  of the file from which command input is
               being read.  An error occurs if the name is not known.
               Equivalent to ‘$argv[number]’.
       $*      Equivalent to ‘$argv’, which is equivalent to ‘$argv[*]’.

       The ‘:’ modifiers described  under  History  substitution,  except  for
       ‘:p’,  can be applied to the substitutions above.  More than one may be
       used.  (+) Braces may be needed to  insulate  a  variable  substitution
       from a literal colon just as with History substitution (q.v.); any mod-
       ifiers must appear within the braces.

       The following substitutions can not be modified with ‘:’ modifiers.

               Substitutes the string ‘1’ if name is set, ‘0’ if it is not.
       $?0     Substitutes ‘1’ if the current input filename is known, ‘0’  if
               it is not.  Always ‘0’ in interactive shells.
               Substitutes the number of words in name.
       $#      Equivalent to ‘$#argv’.  (+)
               Substitutes the number of characters in name.  (+)
               Substitutes the number of characters in $argv[number].  (+)
       $?      Equivalent to ‘$status’.  (+)
       $$      Substitutes the (decimal) process number of the (parent) shell.
       $!      Substitutes the (decimal) process number of the last background
               process started by this shell.  (+)
       $_      Substitutes the command line of the last command executed.  (+)
       $<      Substitutes a line from the standard  input,  with  no  further
               interpretation  thereafter.   It  can  be used to read from the
               keyboard in a shell script.  (+) While csh always quotes $<, as
               if  it  were equivalent to ‘$<:q’, tcsh does not.  Furthermore,
               when tcsh is waiting for a line to be typed the user  may  type
               an  interrupt  to interrupt the sequence into which the line is
               to be substituted, but csh does not allow this.

       The editor command expand-variables, normally bound to ‘^X-$’,  can  be
       used to interactively expand individual variables.

   Command, filename and directory stack substitution
       The remaining substitutions are applied selectively to the arguments of
       builtin commands.  This means that portions of  expressions  which  are
       not  evaluated  are  not  subjected  to these expansions.  For commands
       which are not internal to the shell, the command  name  is  substituted
       separately from the argument list.  This occurs very late, after input-
       output redirection is performed, and in a child of the main shell.

   Command substitution
       Command substitution is indicated by a command enclosed  in  ‘‘’.   The
       output  from  such  a  command is broken into separate words at blanks,
       tabs and newlines, and null words are discarded.  The output  is  vari-
       able and command substituted and put in place of the original string.

       Command  substitutions  inside  double  quotes  (‘"’) retain blanks and
       tabs; only newlines force new words.  The single final newline does not
       force  a  new word in any case.  It is thus possible for a command sub-
       stitution to yield only part of a word, even if the command  outputs  a
       complete line.

       By  default, the shell since version 6.12 replaces all newline and car-
       riage return characters in the command by spaces.  If this is  switched
       off by unsetting csubstnonl, newlines separate commands as usual.

   Filename substitution
       If a word contains any of the characters ‘*’, ‘?’, ‘[’ or ‘{’ or begins
       with the character ‘~’ it is a  candidate  for  filename  substitution,
       also  known  as  ‘‘globbing’’.  This word is then regarded as a pattern
       (‘‘glob-pattern’’), and replaced with an alphabetically sorted list  of
       file names which match the pattern.

       In matching filenames, the character ‘.’ at the beginning of a filename
       or immediately following a ‘/’, as well as the character  ‘/’  must  be
       matched  explicitly.   The  character ‘*’ matches any string of charac-
       ters, including the null string.  The character ‘?’ matches any  single
       character.   The  sequence  ‘[...]’  matches  any one of the characters
       enclosed.  Within ‘[...]’,  a  pair  of  characters  separated  by  ‘-’
       matches any character lexically between the two.

       (+)  Some  glob-patterns  can be negated: The sequence ‘[^...]’ matches
       any single character not specified by the characters and/or  ranges  of
       characters in the braces.

       An entire glob-pattern can also be negated with ‘^’:

           > echo *
           bang crash crunch ouch
           > echo ^cr*
           bang ouch

       Glob-patterns  which  do not use ‘?’, ‘*’, or ‘[]’ or which use ‘{}’ or
       ‘~’ (below) are not negated correctly.

       The metanotation ‘a{b,c,d}e’ is a shorthand for ‘abe ace  ade’.   Left-
       to-right  order  is preserved: ‘/usr/source/s1/{oldls,ls}.c’ expands to
       ‘/usr/source/s1/oldls.c /usr/source/s1/ls.c’.  The results  of  matches
       are   sorted  separately  at  a  low  level  to  preserve  this  order:
       ‘../{memo,*box}’ might expand to ‘../memo ../box ../mbox’.  (Note  that
       ‘memo’  was not sorted with the results of matching ‘*box’.)  It is not
       an error when this construct expands to files which do not  exist,  but
       it  is  possible  to  get an error from a command to which the expanded
       list is passed.  This construct may be nested.  As a special  case  the
       words ‘{’, ‘}’ and ‘{}’ are passed undisturbed.

       The  character ‘~’ at the beginning of a filename refers to home direc-
       tories.  Standing alone, i.e., ‘~’, it expands to  the  invoker’s  home
       directory  as  reflected in the value of the home shell variable.  When
       followed by a name consisting of letters, digits and ‘-’ characters the
       shell  searches  for  a  user with that name and substitutes their home
       directory; thus ‘~ken’ might expand to ‘/usr/ken’ and ‘~ken/chmach’  to
       ‘/usr/ken/chmach’.   If  the  character  ‘~’ is followed by a character
       other than a letter or ‘/’ or appears elsewhere than at  the  beginning
       of  a  word,  it  is  left undisturbed.  A command like ‘setenv MANPATH
       /usr/man:/usr/local/man:~/lib/man’ does not, therefore, do home  direc-
       tory substitution as one might hope.

       It is an error for a glob-pattern containing ‘*’, ‘?’, ‘[’ or ‘~’, with
       or without ‘^’, not to match any files.  However, only one pattern in a
       list  of  glob-patterns  must  match a file (so that, e.g., ‘rm *.a *.c
       *.o’ would fail only if there were no files in  the  current  directory
       ending  in ‘.a’, ‘.c’, or ‘.o’), and if the nonomatch shell variable is
       set a pattern (or list of  patterns)  which  matches  nothing  is  left
       unchanged rather than causing an error.

       The  noglob shell variable can be set to prevent filename substitution,
       and the expand-glob editor command, normally bound to  ‘^X-*’,  can  be
       used to interactively expand individual filename substitutions.

   Directory stack substitution (+)
       The  directory stack is a list of directories, numbered from zero, used
       by the pushd, popd and dirs builtin commands (q.v.).  dirs  can  print,
       store in a file, restore and clear the directory stack at any time, and
       the savedirs and dirsfile shell variables  can  be  set  to  store  the
       directory  stack  automatically on logout and restore it on login.  The
       dirstack shell variable can be examined to see the directory stack  and
       set to put arbitrary directories into the directory stack.

       The character ‘=’ followed by one or more digits expands to an entry in
       the directory stack.  The special case ‘=-’ expands to the last  direc-
       tory in the stack.  For example,

           > dirs -v
           0       /usr/bin
           1       /usr/spool/uucp
           2       /usr/accts/sys
           > echo =1
           > echo =0/calendar
           > echo =-

       The  noglob  and  nonomatch  shell variables and the expand-glob editor
       command apply to directory stack as well as filename substitutions.

   Other substitutions (+)
       There  are  several  more  transformations  involving  filenames,   not
       strictly related to the above but mentioned here for completeness.  Any
       filename may be expanded to a full  path  when  the  symlinks  variable
       (q.v.)  is  set  to ‘expand’.  Quoting prevents this expansion, and the
       normalize-path editor command does it on demand.  The normalize-command
       editor  command  expands  commands  in  PATH into full paths on demand.
       Finally, cd and pushd  interpret  ‘-’  as  the  old  working  directory
       (equivalent  to the shell variable owd).  This is not a substitution at
       all, but an abbreviation recognized by only those  commands.   Nonethe-
       less, it too can be prevented by quoting.

       The  next  three  sections describe how the shell executes commands and
       deals with their input and output.

   Simple commands, pipelines and sequences
       A simple command is a sequence of words, the first of  which  specifies
       the  command to be executed.  A series of simple commands joined by ‘|’
       characters forms a pipeline.  The output of each command in a  pipeline
       is connected to the input of the next.

       Simple  commands  and  pipelines may be joined into sequences with ‘;’,
       and will be executed sequentially.  Commands and pipelines can also  be
       joined  into  sequences with ‘||’ or ‘&&’, indicating, as in the C lan-
       guage, that the second is to be executed only if  the  first  fails  or
       succeeds respectively.

       A  simple  command,  pipeline or sequence may be placed in parentheses,
       ‘()’, to form a simple command, which may in turn be a component  of  a
       pipeline  or sequence.  A command, pipeline or sequence can be executed
       without waiting for it to terminate by following it with an ‘&’.

   Builtin and non-builtin command execution
       Builtin commands are executed within the shell.  If any component of  a
       pipeline except the last is a builtin command, the pipeline is executed
       in a subshell.

       Parenthesized commands are always executed in a subshell.

           (cd; pwd); pwd

       thus prints the home directory, leaving you where  you  were  (printing
       this after the home directory), while

           cd; pwd

       leaves  you  in  the  home  directory.  Parenthesized commands are most
       often used to prevent cd from affecting the current shell.

       When a command to be executed is found not to be a builtin command  the
       shell  attempts to execute the command via execve(2).  Each word in the
       variable path names a directory in which the shell will  look  for  the
       command.  If it is given neither a -c nor a -t option, the shell hashes
       the names in these directories into an internal table so that  it  will
       try  an execve(2) in only a directory where there is a possibility that
       the command resides there.  This greatly speeds command location when a
       large  number  of  directories are present in the search path.  If this
       mechanism has been turned off (via unhash), if the shell was given a -c
       or  -t  argument  or  in  any case for each directory component of path
       which does not begin with a ‘/’, the  shell  concatenates  the  current
       working  directory with the given command name to form a path name of a
       file which it then attempts to execute.

       If the file has execute permissions but is not  an  executable  to  the
       system  (i.e.,  it  is  neither  an executable binary nor a script that
       specifies its interpreter), then it is assumed to be a file  containing
       shell  commands  and a new shell is spawned to read it.  The shell spe-
       cial alias may be set to specify an interpreter other  than  the  shell

       On  systems which do not understand the ‘#!’ script interpreter conven-
       tion the shell may be compiled to emulate it;  see  the  version  shell
       variable.  If so, the shell checks the first line of the file to see if
       it is of the form ‘#!interpreter arg ...’.  If it is, the shell  starts
       interpreter  with  the  given args and feeds the file to it on standard

       The standard input and standard output of a command may  be  redirected
       with the following syntax:

       < name  Open  file  name (which is first variable, command and filename
               expanded) as the standard input.
       << word Read the shell input up to a line which is identical  to  word.
               word  is not subjected to variable, filename or command substi-
               tution, and each input line is compared to word before any sub-
               stitutions  are done on this input line.  Unless a quoting ‘\’,
               ‘"’, ‘’ or ‘‘’ appears in word variable and  command  substitu-
               tion  is  performed  on  the intervening lines, allowing ‘\’ to
               quote ‘$’, ‘\’ and ‘‘’.  Commands which  are  substituted  have
               all  blanks, tabs, and newlines preserved, except for the final
               newline which is dropped.  The resultant text is placed  in  an
               anonymous temporary file which is given to the command as stan-
               dard input.
       > name
       >! name
       >& name
       >&! name
               The file name is used as standard output.  If the file does not
               exist  then it is created; if the file exists, it is truncated,
               its previous contents being lost.

               If the shell variable noclobber is set, then the file must  not
               exist  or  be  a  character  special  file (e.g., a terminal or
               ‘/dev/null’) or an error results.  This helps prevent  acciden-
               tal  destruction  of  files.  In this case the ‘!’ forms can be
               used to suppress this check.

               The forms involving ‘&’ route the diagnostic  output  into  the
               specified  file  as  well  as  the  standard  output.   name is
               expanded in the same way as ‘<’ input filenames are.
       >> name
       >>& name
       >>! name
       >>&! name
               Like ‘>’, but appends output to the end of name.  If the  shell
               variable noclobber is set, then it is an error for the file not
               to exist, unless one of the ‘!’ forms is given.

       A command receives the environment in which the shell  was  invoked  as
       modified by the input-output parameters and the presence of the command
       in a pipeline.  Thus, unlike some previous shells, commands run from  a
       file  of  shell  commands have no access to the text of the commands by
       default; rather they receive the original standard input of the  shell.
       The ‘<<’ mechanism should be used to present inline data.  This permits
       shell command scripts to function as components of pipelines and allows
       the  shell  to  block  read  its input.  Note that the default standard
       input for a command run detached is not the empty file  /dev/null,  but
       the original standard input of the shell.  If this is a terminal and if
       the process attempts to read from the terminal, then the  process  will
       block and the user will be notified (see Jobs).

       Diagnostic output may be directed through a pipe with the standard out-
       put.  Simply use the form ‘|&’ rather than just ‘|’.

       The shell cannot presently  redirect  diagnostic  output  without  also
       redirecting  standard  output,  but  ‘(command > output-file) >& error-
       file’ is often an acceptable workaround.  Either output-file or  error-
       file may be ‘/dev/tty’ to send output to the terminal.

       Having  described  how  the  shell accepts, parses and executes command
       lines, we now turn to a variety of its useful features.

   Control flow
       The shell contains a number of commands which can be used  to  regulate
       the  flow  of  control in command files (shell scripts) and (in limited
       but useful ways) from terminal input.  These commands  all  operate  by
       forcing the shell to reread or skip in its input and, due to the imple-
       mentation, restrict the placement of some of the commands.

       The foreach, switch, and while statements, as well as the  if-then-else
       form  of  the if statement, require that the major keywords appear in a
       single simple command on an input line as shown below.

       If the shell’s input is not seekable, the shell buffers up input  when-
       ever a loop is being read and performs seeks in this internal buffer to
       accomplish the rereading implied by the loop.  (To the extent that this
       allows, backward gotos will succeed on non-seekable inputs.)

       The  if,  while and exit builtin commands use expressions with a common
       syntax.  The expressions can include any of the operators described  in
       the  next  three  sections.  Note that the @ builtin command (q.v.) has
       its own separate syntax.

   Logical, arithmetical and comparison operators
       These operators are similar to those of C and have the same precedence.
       They include

           ||  &&  |  ^  &  ==  !=  =~  !~  <=  >=
           <  > <<  >>  +  -  *  /  %  !  ~  (  )

       Here  the  precedence  increases to the right, ‘==’ ‘!=’ ‘=~’ and ‘!~’,
       ‘<=’ ‘>=’ ‘<’ and ‘>’, ‘<<’ and ‘>>’, ‘+’ and  ‘-’,  ‘*’  ‘/’  and  ‘%’
       being, in groups, at the same level.  The ‘==’ ‘!=’ ‘=~’ and ‘!~’ oper-
       ators compare their arguments as strings; all others  operate  on  num-
       bers.   The  operators ‘=~’ and ‘!~’ are like ‘!=’ and ‘==’ except that
       the right hand side  is  a  glob-pattern  (see  Filename  substitution)
       against  which the left hand operand is matched.  This reduces the need
       for use of the switch builtin command in shell scripts when all that is
       really needed is pattern matching.

       Strings  which  begin  with  ‘0’ are considered octal numbers.  Null or
       missing arguments are considered ‘0’.  The results of  all  expressions
       are  strings, which represent decimal numbers.  It is important to note
       that no two components of an expression can appear in  the  same  word;
       except  when  adjacent to components of expressions which are syntacti-
       cally significant to the parser (‘&’ ‘|’ ‘<’ ‘>’ ‘(’ ‘)’)  they  should
       be surrounded by spaces.

   Command exit status
       Commands  can be executed in expressions and their exit status returned
       by enclosing them in braces (‘{}’).  Remember that the braces should be
       separated  from the words of the command by spaces.  Command executions
       succeed, returning true, i.e., ‘1’, if the command exits with status 0,
       otherwise they fail, returning false, i.e., ‘0’.  If more detailed sta-
       tus information is required then the command should be executed outside
       of an expression and the status shell variable examined.

   File inquiry operators
       Some  of  these operators perform true/false tests on files and related
       objects.  They are of the form -op file, where op is one of

           r   Read access
           w   Write access
           x   Execute access
           X   Executable in the path or shell builtin, e.g., ‘-X ls’ and  ‘-X
               ls-F’ are generally true, but ‘-X /bin/ls’ is not (+)
           e   Existence
           o   Ownership
           z   Zero size
           s   Non-zero size (+)
           f   Plain file
           d   Directory
           l   Symbolic link (+) *
           b   Block special file (+)
           c   Character special file (+)
           p   Named pipe (fifo) (+) *
           S   Socket special file (+) *
           u   Set-user-ID bit is set (+)
           g   Set-group-ID bit is set (+)
           k   Sticky bit is set (+)
           t   file  (which  must be a digit) is an open file descriptor for a
               terminal device (+)
           R   Has been migrated (convex only) (+)
           L   Applies subsequent operators in a multiple-operator test  to  a
               symbolic  link rather than to the file to which the link points
               (+) *

       file is command and filename expanded and then tested to see if it  has
       the specified relationship to the real user.  If file does not exist or
       is inaccessible or, for the operators indicated by ‘*’, if  the  speci-
       fied file type does not exist on the current system, then all enquiries
       return false, i.e., ‘0’.

       These operators may be combined for conciseness: ‘-xy file’ is  equiva-
       lent  to ‘-x file && -y file’.  (+) For example, ‘-fx’ is true (returns
       ‘1’) for plain executable files, but not for directories.

       L may be used in a multiple-operator test to apply subsequent operators
       to  a  symbolic  link rather than to the file to which the link points.
       For example, ‘-lLo’ is true for links owned by the invoking user.   Lr,
       Lw  and  Lx are always true for links and false for non-links.  L has a
       different meaning when it is the last operator in  a  multiple-operator
       test; see below.

       It  is  possible  but  not useful, and sometimes misleading, to combine
       operators which expect file to be a file with operators which  do  not,
       (e.g., X and t).  Following L with a non-file operator can lead to par-
       ticularly strange results.

       Other operators return other information, i.e., not just  ‘0’  or  ‘1’.
       (+) They have the same format as before; op may be one of

           A       Last  file  access time, as the number of seconds since the
           A:      Like A, but in timestamp format, e.g., ‘Fri May 14 16:36:10
           M       Last file modification time
           M:      Like M, but in timestamp format
           C       Last inode modification time
           C:      Like C, but in timestamp format
           D       Device number
           I       Inode number
           F       Composite file identifier, in the form device:inode
           L       The name of the file pointed to by a symbolic link
           N       Number of (hard) links
           P       Permissions, in octal, without leading zero
           P:      Like P, with leading zero
           Pmode   Equivalent  to  ‘-P file & mode’, e.g., ‘-P22 file’ returns
                   ‘22’ if file is writable by group and  other,  ‘20’  if  by
                   group only, and ‘0’ if by neither
           Pmode:  Like Pmode:, with leading zero
           U       Numeric userid
           U:      Username, or the numeric userid if the username is unknown
           G       Numeric groupid
           G:      Groupname,  or  the  numeric  groupid  if  the groupname is
           Z       Size, in bytes

       Only one of these operators may appear in a multiple-operator test, and
       it must be the last.  Note that L has a different meaning at the end of
       and elsewhere in a multiple-operator test.   Because  ‘0’  is  a  valid
       return  value  for many of these operators, they do not return ‘0’ when
       they fail: most return ‘-1’, and F returns ‘:’.

       If the shell is compiled with POSIX  defined  (see  the  version  shell
       variable), the result of a file inquiry is based on the permission bits
       of the file and not on the result of the access(2)  system  call.   For
       example, if one tests a file with -w whose permissions would ordinarily
       allow writing but which is on a file system mounted read-only, the test
       will succeed in a POSIX shell but fail in a non-POSIX shell.

       File  inquiry operators can also be evaluated with the filetest builtin
       command (q.v.) (+).

       The shell associates a job with each pipeline.  It  keeps  a  table  of
       current jobs, printed by the jobs command, and assigns them small inte-
       ger numbers.  When a job is started asynchronously with ‘&’, the  shell
       prints a line which looks like

           [1] 1234

       indicating that the job which was started asynchronously was job number
       1 and had one (top-level) process, whose process id was 1234.

       If you are running a job and wish to do something else you may hit  the
       suspend  key  (usually  ‘^Z’), which sends a STOP signal to the current
       job.  The shell will then normally indicate that the job has been ‘Sus-
       pended’  and  print  another prompt.  If the listjobs shell variable is
       set, all jobs will be listed like the jobs builtin command;  if  it  is
       set  to ‘long’ the listing will be in long format, like ‘jobs -l’.  You
       can then manipulate the state of the suspended job.  You can put it  in
       the  ‘‘background’’  with the bg command or run some other commands and
       eventually bring the job back into the ‘‘foreground’’  with  fg.   (See
       also  the  run-fg-editor  editor command.)  A ‘^Z’ takes effect immedi-
       ately and is like an interrupt in that pending output and unread  input
       are  discarded  when  it is typed.  The wait builtin command causes the
       shell to wait for all background jobs to complete.

       The ‘^]’ key sends a delayed suspend signal, which does not generate  a
       STOP signal until a program attempts to read(2) it, to the current job.
       This can usefully be typed ahead when you have prepared  some  commands
       for  a job which you wish to stop after it has read them.  The ‘^Y’ key
       performs this function in csh(1); in tcsh, ‘^Y’ is an editing  command.

       A  job  being  run in the background stops if it tries to read from the
       terminal.  Background jobs are normally allowed to produce output,  but
       this  can  be disabled by giving the command ‘stty tostop’.  If you set
       this tty option, then background jobs will stop when they try  to  pro-
       duce output like they do when they try to read input.

       There  are  several  ways to refer to jobs in the shell.  The character
       ‘%’ introduces a job name.  If you wish to refer to job number  1,  you
       can  name  it  as ‘%1’.  Just naming a job brings it to the foreground;
       thus ‘%1’ is a synonym for ‘fg %1’, bringing job 1 back into the  fore-
       ground.  Similarly, saying ‘%1 &’ resumes job 1 in the background, just
       like ‘bg %1’.  A job can also be named by an unambiguous prefix of  the
       string  typed  in to start it: ‘%ex’ would normally restart a suspended
       ex(1) job, if there were only one suspended job whose name  began  with
       the  string  ‘ex’.   It is also possible to say ‘%?string’ to specify a
       job whose text contains string, if there is only one such job.

       The shell maintains a notion of the current and previous jobs.  In out-
       put  pertaining  to  jobs, the current job is marked with a ‘+’ and the
       previous job with a ‘-’.  The abbreviations ‘%+’, ‘%’, and (by  analogy
       with the syntax of the history mechanism) ‘%%’ all refer to the current
       job, and ‘%-’ refers to the previous job.

       The job control mechanism requires that the stty(1) option ‘new’ be set
       on  some systems.  It is an artifact from a ‘new’ implementation of the
       tty driver which allows generation of  interrupt  characters  from  the
       keyboard  to tell jobs to stop.  See stty(1) and the setty builtin com-
       mand for details on setting options in the new tty driver.

   Status reporting
       The shell learns immediately whenever a process changes state.  It nor-
       mally  informs  you  whenever  a job becomes blocked so that no further
       progress is possible, but only right before it prints a  prompt.   This
       is  done so that it does not otherwise disturb your work.  If, however,
       you set the shell variable notify, the shell will  notify  you  immedi-
       ately  of  changes of status in background jobs.  There is also a shell
       command notify which marks a single process so that its status  changes
       will be immediately reported.  By default notify marks the current pro-
       cess; simply say ‘notify’ after starting a background job to mark it.

       When you try to leave the shell while jobs are  stopped,  you  will  be
       warned  that  ‘You  have stopped jobs.’ You may use the jobs command to
       see what they are.  If you do this or immediately try  to  exit  again,
       the  shell will not warn you a second time, and the suspended jobs will
       be terminated.

   Automatic, periodic and timed events (+)
       There are various ways to run commands and take other actions automati-
       cally  at  various  times in the ‘‘life cycle’’ of the shell.  They are
       summarized here, and described in detail under the appropriate  Builtin
       commands, Special shell variables and Special aliases.

       The  sched  builtin command puts commands in a scheduled-event list, to
       be executed by the shell at a given time.

       The beepcmd, cwdcmd, periodic,  precmd,  postcmd,  and  jobcmd  Special
       aliases  can  be  set, respectively, to execute commands when the shell
       wants to ring the bell, when the working directory changes, every  tpe-
       riod  minutes,  before  each prompt, before each command gets executed,
       after each command gets executed, and when  a  job  is  started  or  is
       brought into the foreground.

       The  autologout  shell variable can be set to log out or lock the shell
       after a given number of minutes of inactivity.

       The mail shell variable can be set to check for new mail  periodically.

       The  printexitvalue  shell variable can be set to print the exit status
       of commands which exit with a status other than zero.

       The rmstar shell variable can be set to ask the user, when  ‘rm  *’  is
       typed, if that is really what was meant.

       The  time shell variable can be set to execute the time builtin command
       after the completion of any process that takes more than a given number
       of CPU seconds.

       The  watch  and  who shell variables can be set to report when selected
       users log in or out, and the log builtin command reports on those users
       at any time.

   Native Language System support (+)
       The  shell  is  eight  bit clean (if so compiled; see the version shell
       variable) and thus supports character  sets  needing  this  capability.
       NLS  support differs depending on whether or not the shell was compiled
       to use the system’s NLS (again, see version).  In  either  case,  7-bit
       ASCII  is the default character code (e.g., the classification of which
       characters are  printable)  and  sorting,  and  changing  the  LANG  or
       LC_CTYPE  environment  variables causes a check for possible changes in
       these respects.

       When using the system’s NLS, the setlocale(3)  function  is  called  to
       determine  appropriate character code/classification and sorting (e.g.,
       a ’en_CA.UTF-8’ would yield "UTF-8" as a character code).   This  func-
       tion  typically  examines  the LANG and LC_CTYPE environment variables;
       refer to the system documentation for further details.  When not  using
       the  system’s  NLS,  the  shell  simulates  it by assuming that the ISO
       8859-1 character set is used whenever either of the LANG  and  LC_CTYPE
       variables are set, regardless of their values.  Sorting is not affected
       for the simulated NLS.

       In addition, with both real and simulated NLS, all printable characters
       in  the  range  \200-\377,  i.e.,  those that have M-char bindings, are
       automatically rebound to self-insert-command.  The corresponding  bind-
       ing for the escape-char sequence, if any, is left alone.  These charac-
       ters are not rebound if the NOREBIND environment variable is set.  This
       may  be  useful  for  the  simulated  NLS or a primitive real NLS which
       assumes full ISO 8859-1.  Otherwise, all M-char bindings in  the  range
       \240-\377  are  effectively  undone.  Explicitly rebinding the relevant
       keys with bindkey is of course still possible.

       Unknown characters (i.e., those that are neither printable nor  control
       characters) are printed in the format \nnn.  If the tty is not in 8 bit
       mode, other 8 bit characters are printed by converting  them  to  ASCII
       and  using  standout mode.  The shell never changes the 7/8 bit mode of
       the tty and tracks user-initiated changes of 7/8 bit mode.   NLS  users
       (or,  for  that  matter,  those who want to use a meta key) may need to
       explicitly set the tty in 8 bit mode through  the  appropriate  stty(1)
       command in, e.g., the ~/.login file.

   OS variant support (+)
       A  number  of  new builtin commands are provided to support features in
       particular operating systems.  All  are  described  in  detail  in  the
       Builtin commands section.

       On  systems  that  support  TCF  (aix-ibm370,  aix-ps2),  getspath  and
       setspath get and set the system execution path, getxvers  and  setxvers
       get  and  set the experimental version prefix and migrate migrates pro-
       cesses between sites.  The jobs builtin prints the site on  which  each
       job is executing.

       Under  BS2000,  bs2cmd  executes  commands of the underlying BS2000/OSD
       operating system.

       Under Domain/OS, inlib adds shared libraries to  the  current  environ-
       ment, rootnode changes the rootnode and ver changes the systype.

       Under Mach, setpath is equivalent to Mach’s setpath(1).

       Under Masscomp/RTU and Harris CX/UX, universe sets the universe.

       Under  Harris  CX/UX,  ucb  or  att  runs a command under the specified

       Under Convex/OS, warp prints or sets the universe.

       The VENDOR, OSTYPE and MACHTYPE environment variables indicate  respec-
       tively  the  vendor,  operating system and machine type (microprocessor
       class or machine model) of the system on which the shell thinks  it  is
       running.   These are particularly useful when sharing one’s home direc-
       tory between several types of machines; one can, for example,

           set path = (~/bin.$MACHTYPE /usr/ucb /bin /usr/bin .)

       in one’s ~/.login and put executables compiled for each machine in  the
       appropriate directory.

       The  version shell variable indicates what options were chosen when the
       shell was compiled.

       Note also the newgrp builtin, the afsuser and  echo_style  shell  vari-
       ables  and  the  system-dependent  locations of the shell’s input files
       (see FILES).

   Signal handling
       Login shells ignore interrupts when reading the  file  ~/.logout.   The
       shell  ignores quit signals unless started with -q.  Login shells catch
       the terminate signal, but non-login shells inherit the terminate behav-
       ior  from their parents.  Other signals have the values which the shell
       inherited from its parent.

       In shell scripts, the shell’s handling of interrupt and terminate  sig-
       nals  can be controlled with onintr, and its handling of hangups can be
       controlled with hup and nohup.

       The shell exits on a hangup (see also the logout shell  variable).   By
       default,  the shell’s children do too, but the shell does not send them
       a hangup when it exits.  hup arranges for the shell to send a hangup to
       a child when it exits, and nohup sets a child to ignore hangups.

   Terminal management (+)
       The  shell  uses  three  different  sets  of  terminal (‘‘tty’’) modes:
       ‘edit’, used when editing, ‘quote’, used when quoting  literal  charac-
       ters,  and  ‘execute’,  used  when executing commands.  The shell holds
       some settings in each mode constant, so commands which leave the tty in
       a  confused  state  do  not  interfere  with the shell.  The shell also
       matches changes in the speed and padding of the tty.  The list  of  tty
       modes  that  are  kept  constant  can be examined and modified with the
       setty builtin.  Note that although the editor uses CBREAK mode (or  its
       equivalent), it takes typed-ahead characters anyway.

       The  echotc,  settc  and  telltc commands can be used to manipulate and
       debug terminal capabilities from the command line.

       On systems that support SIGWINCH or SIGWINDOW, the shell adapts to win-
       dow  resizing automatically and adjusts the environment variables LINES
       and COLUMNS if set.  If the environment variable TERMCAP  contains  li#
       and  co# fields, the shell adjusts them to reflect the new window size.


       The next sections of this manual describe all of the available  Builtin
       commands, Special aliases and Special shell variables.

   Builtin commands
       %job    A synonym for the fg builtin command.

       %job &  A synonym for the bg builtin command.

       :       Does nothing, successfully.

       @ name = expr
       @ name[index] = expr
       @ name++|--
       @ name[index]++|--
               The first form prints the values of all shell variables.

               The  second  form assigns the value of expr to name.  The third
               form assigns the value of expr to  the  index’th  component  of
               name;  both name and its index’th component must already exist.

               expr may contain the operators ‘*’, ‘+’, etc.,  as  in  C.   If
               expr  contains  ‘<’,  ‘>’, ‘&’ or ‘’ then at least that part of
               expr must be placed within ‘()’.  Note that the syntax of  expr
               has nothing to do with that described under Expressions.

               The fourth and fifth forms increment (‘++’) or decrement (‘--’)
               name or its index’th component.

               The space between ‘@’ and name is required.  The spaces between
               name and ‘=’ and between ‘=’ and expr are optional.  Components
               of expr must be separated by spaces.

       alias [name [wordlist]]
               Without arguments, prints all aliases.  With name,  prints  the
               alias  for  name.   With name and wordlist, assigns wordlist as
               the alias of name.  wordlist is command  and  filename  substi-
               tuted.   name  may  not  be ‘alias’ or ‘unalias’.  See also the
               unalias builtin command.

       alloc   Shows the amount of dynamic memory acquired, broken  down  into
               used  and  free  memory.   With an argument shows the number of
               free and used blocks in each  size  category.   The  categories
               start at size 8 and double at each step.  This command’s output
               may vary across system types, because systems  other  than  the
               VAX may use a different memory allocator.

       bg [%job ...]
               Puts  the  specified  jobs  (or, without arguments, the current
               job) into the background, continuing each  if  it  is  stopped.
               job may be a number, a string, ‘’, ‘%’, ‘+’ or ‘-’ as described
               under Jobs.

       bindkey [-l|-d|-e|-v|-u] (+)
       bindkey [-a] [-b] [-k] [-r] [--] key (+)
       bindkey [-a] [-b] [-k] [-c|-s] [--] key command (+)
               Without options, the first form lists all bound  keys  and  the
               editor  command  to  which each is bound, the second form lists
               the editor command to which key is bound  and  the  third  form
               binds the editor command command to key.  Options include:

               -l  Lists  all editor commands and a short description of each.
               -d  Binds all keys to the standard  bindings  for  the  default
               -e  Binds all keys to the standard GNU Emacs-like bindings.
               -v  Binds all keys to the standard vi(1)-like bindings.
               -a  Lists  or  changes key-bindings in the alternative key map.
                   This is the key map used in vi command mode.
               -b  key is interpreted as a control character written  ^charac-
                   ter (e.g., ‘^A’) or C-character (e.g., ‘C-A’), a meta char-
                   acter written M-character (e.g.,  ‘M-A’),  a  function  key
                   written  F-string (e.g., ‘F-string’), or an extended prefix
                   key written X-character (e.g., ‘X-A’).
               -k  key is interpreted as a symbolic arrow key name, which  may
                   be one of ‘down’, ‘up’, ‘left’ or ‘right’.
               -r  Removes  key’s  binding.  Be careful: ‘bindkey -r’ does not
                   bind key to self-insert-command (q.v.), it unbinds key com-
               -c  command  is  interpreted  as  a builtin or external command
                   instead of an editor command.
               -s  command is taken as a literal string and treated as  termi-
                   nal  input  when  key  is typed.  Bound keys in command are
                   themselves reinterpreted, and this continues for ten levels
                   of interpretation.
               --  Forces  a break from option processing, so the next word is
                   taken as key even if it begins with ’-’.
               -u (or any invalid option)
                   Prints a usage message.

               key may be a single character or a string.   If  a  command  is
               bound  to  a string, the first character of the string is bound
               to sequence-lead-in and the entire string is bound to the  com-

               Control  characters in key can be literal (they can be typed by
               preceding them with the editor command quoted-insert,  normally
               bound  to  ‘^V’)  or written caret-character style, e.g., ‘^A’.
               Delete is written ‘^?’  (caret-question mark).  key and command
               can  contain backslashed escape sequences (in the style of Sys-
               tem V echo(1)) as follows:

                   \a      Bell
                   \b      Backspace
                   \e      Escape
                   \f      Form feed
                   \n      Newline
                   \r      Carriage return
                   \t      Horizontal tab
                   \v      Vertical tab
                   \nnn    The ASCII character corresponding to the octal num-
                           ber nnn

               ‘\’  nullifies  the special meaning of the following character,
               if it has any, notably ‘\’ and ‘^’.

       bs2cmd bs2000-command (+)
               Passes bs2000-command to the  BS2000  command  interpreter  for
               execution.  Only  non-interactive commands can be executed, and
               it is not possible to execute any command  that  would  overlay
               the image of the current process, like /EXECUTE or /CALL-PROCE-
               DURE. (BS2000 only)

       break   Causes execution to resume after the end of the nearest enclos-
               ing  foreach  or  while.  The remaining commands on the current
               line are executed.  Multi-level breaks  are  thus  possible  by
               writing them all on one line.

       breaksw Causes a break from a switch, resuming after the endsw.

       builtins (+)
               Prints the names of all builtin commands.

       bye (+) A  synonym  for  the logout builtin command.  Available only if
               the shell was so compiled; see the version shell variable.

       case label:
               A label in a switch statement as discussed below.

       cd [-p] [-l] [-n|-v] [name]
               If a directory name  is  given,  changes  the  shell’s  working
               directory to name.  If not, changes to home.  If name is ‘-’ it
               is interpreted as the previous  working  directory  (see  Other
               substitutions).   (+) If name is not a subdirectory of the cur-
               rent directory (and does not begin with ‘/’,  ‘./’  or  ‘../’),
               each  component  of the variable cdpath is checked to see if it
               has a subdirectory name.  Finally, if all else fails  but  name
               is  a  shell variable whose value begins with ‘/’, then this is
               tried to see if it is a directory.

               With -p, prints the final directory stack, just like dirs.  The
               -l,  -n and -v flags have the same effect on cd as on dirs, and
               they imply -p.  (+)

               See also the implicitcd shell variable.

       chdir   A synonym for the cd builtin command.

       complete [command [word/pattern/list[:select]/[[suffix]/] ...]] (+)
               Without arguments, lists all completions.  With command,  lists
               completions  for  command.  With command and word etc., defines

               command may be a full command name or a glob-pattern (see File-
               name  substitution).   It  can  begin with ‘-’ to indicate that
               completion should be used only when command is ambiguous.

               word specifies which word relative to the current word is to be
               completed, and may be one of the following:

                   c   Current-word  completion.   pattern  is  a glob-pattern
                       which must match the beginning of the current  word  on
                       the  command  line.  pattern is ignored when completing
                       the current word.
                   C   Like c, but includes pattern when completing  the  cur-
                       rent word.
                   n   Next-word  completion.  pattern is a glob-pattern which
                       must match the beginning of the previous  word  on  the
                       command line.
                   N   Like  n,  but  must match the beginning of the word two
                       before the current word.
                   p   Position-dependent completion.  pattern  is  a  numeric
                       range,  with  the same syntax used to index shell vari-
                       ables, which must include the current word.

               list, the list of possible completions, may be one of the  fol-

                   a       Aliases
                   b       Bindings (editor commands)
                   c       Commands (builtin or external commands)
                   C       External  commands  which  begin  with the supplied
                           path prefix
                   d       Directories
                   D       Directories which begin with the supplied path pre-
                   e       Environment variables
                   f       Filenames
                   F       Filenames which begin with the supplied path prefix
                   g       Groupnames
                   j       Jobs
                   l       Limits
                   n       Nothing
                   s       Shell variables
                   S       Signals
                   t       Plain (‘‘text’’) files
                   T       Plain (‘‘text’’) files which begin  with  the  sup-
                           plied path prefix
                   v       Any variables
                   u       Usernames
                   x       Like  n,  but  prints  select  when list-choices is
                   X       Completions
                   $var    Words from the variable var
                   (...)   Words from the given list
                   ‘...‘   Words from the output of command

               select is an optional glob-pattern.  If given, words from  only
               list  that  match  select  are considered and the fignore shell
               variable is ignored.  The last three types  of  completion  may
               not  have a select pattern, and x uses select as an explanatory
               message when the list-choices editor command is used.

               suffix is a single character to be  appended  to  a  successful
               completion.  If null, no character is appended.  If omitted (in
               which case the fourth delimiter can also be omitted),  a  slash
               is appended to directories and a space to other words.

               Now  for some examples.  Some commands take only directories as
               arguments, so there’s no point completing plain files.

                   > complete cd ’p/1/d/’

               completes only the first word following  ‘cd’  (‘p/1’)  with  a
               directory.   p-type  completion can also be used to narrow down
               command completion:

                   > co[^D]
                   complete compress
                   > complete -co* ’p/0/(compress)/’
                   > co[^D]
                   > compress

               This completion completes commands (words in position 0, ‘p/0’)
               which  begin with ‘co’ (thus matching ‘co*’) to ‘compress’ (the
               only word in the list).  The leading ‘-’  indicates  that  this
               completion is to be used with only ambiguous commands.

                   > complete find ’n/-user/u/’

               is  an example of n-type completion.  Any word following ‘find’
               and immediately following ‘-user’ is completed from the list of

                   > complete cc ’c/-I/d/’

               demonstrates  c-type  completion.   Any word following ‘cc’ and
               beginning with ‘-I’ is completed as a directory.  ‘-I’  is  not
               taken as part of the directory because we used lowercase c.

               Different lists are useful with different commands.

                   > complete alias ’p/1/a/’
                   > complete man ’p/*/c/’
                   > complete set ’p/1/s/’
                   > complete true ’p/1/x:Truth has no options./’

               These complete words following ‘alias’ with aliases, ‘man’ with
               commands, and ‘set’ with shell variables.  ‘true’ doesn’t  have
               any options, so x does nothing when completion is attempted and
               prints ‘Truth has no  options.’  when  completion  choices  are

               Note  that  the  man example, and several other examples below,
               could just as well have used ’c/*’ or ’n/*’ as ’p/*’.

               Words can be completed from a variable evaluated at  completion

                   > complete ftp ’p/1/$hostnames/’
                   > set hostnames = (rtfm.mit.edu tesla.ee.cornell.edu)
                   > ftp [^D]
                   rtfm.mit.edu tesla.ee.cornell.edu
                   > ftp [^C]
                   >   set   hostnames  =  (rtfm.mit.edu  tesla.ee.cornell.edu
                   > ftp [^D]
                   rtfm.mit.edu tesla.ee.cornell.edu uunet.uu.net

               or from a command run at completion time:

                   > complete kill ’p/*/‘ps | awk \{print\ \$1\}‘/’
                   > kill -9 [^D]
                   23113 23377 23380 23406 23429 23529 23530 PID

               Note that the complete command does not itself quote its  argu-
               ments,  so  the  braces,  space and ‘$’ in ‘{print $1}’ must be
               quoted explicitly.

               One command can have multiple completions:

                   > complete dbx ’p/2/(core)/’ ’p/*/c/’

               completes the second argument to ‘dbx’ with the word ‘core’ and
               all  other  arguments  with commands.  Note that the positional
               completion  is  specified  before  the  next-word   completion.
               Because  completions  are  evaluated from left to right, if the
               next-word completion were specified first it would always match
               and the positional completion would never be executed.  This is
               a common mistake when defining a completion.

               The select pattern is useful when a command  takes  files  with
               only particular forms as arguments.  For example,

                   > complete cc ’p/*/f:*.[cao]/’

               completes ‘cc’ arguments to files ending in only ‘.c’, ‘.a’, or
               ‘.o’.  select can also exclude files, using negation of a glob-
               pattern  as  described  under Filename substitution.  One might

                   > complete rm ’p/*/f:^*.{c,h,cc,C,tex,1,man,l,y}/’

               to exclude precious  source  code  from  ‘rm’  completion.   Of
               course,  one  could still type excluded names manually or over-
               ride the completion mechanism using  the  complete-word-raw  or
               list-choices-raw editor commands (q.v.).

               The  ‘C’, ‘D’, ‘F’ and ‘T’ lists are like ‘c’, ‘d’, ‘f’ and ‘t’
               respectively, but they use the select argument in  a  different
               way:  to restrict completion to files beginning with a particu-
               lar path prefix.  For example, the Elm mail program uses ‘=’ as
               an abbreviation for one’s mail directory.  One might use

                   > complete elm c@=@F:$HOME/Mail/@

               to  complete  ‘elm  -f =’ as if it were ‘elm -f ~/Mail/’.  Note
               that we used ‘@’ instead of ‘/’ to  avoid  confusion  with  the
               select  argument,  and  we  used ‘$HOME’ instead of ‘~’ because
               home directory substitution works at only the  beginning  of  a

               suffix  is  used  to add a nonstandard suffix (not space or ‘/’
               for directories) to completed words.

                   > complete finger ’c/*@/$hostnames/’ ’p/1/u/@’

               completes arguments to ‘finger’ from the list of users, appends
               an  ‘@’,  and then completes after the ‘@’ from the ‘hostnames’
               variable.  Note again the order in which  the  completions  are

               Finally, here’s a complex example for inspiration:

                   > complete find \
                   ’n/-name/f/’ ’n/-newer/f/’ ’n/-{,n}cpio/f/’ \
                   ´n/-exec/c/’ ’n/-ok/c/’ ’n/-user/u/’ \
                   ’n/-group/g/’ ’n/-fstype/(nfs 4.2)/’ \
                   ’n/-type/(b c d f l p s)/’ \
                   ´c/-/(name newer cpio ncpio exec ok user \
                   group fstype type atime ctime depth inum \
                   ls mtime nogroup nouser perm print prune \
                   size xdev)/’ \

               This  completes  words  following ‘-name’, ‘-newer’, ‘-cpio’ or
               ‘ncpio’ (note the pattern which matches both) to  files,  words
               following  ‘-exec’ or ‘-ok’ to commands, words following ‘user’
               and ‘group’ to users and groups respectively and words  follow-
               ing  ‘-fstype’  or  ‘-type’  to members of the given lists.  It
               also completes the switches  themselves  from  the  given  list
               (note  the use of c-type completion) and completes anything not
               otherwise completed to a directory.  Whew.

               Remember that programmed completions are ignored  if  the  word
               being completed is a tilde substitution (beginning with ‘~’) or
               a variable (beginning with ‘$’).  complete is  an  experimental
               feature,  and  the  syntax may change in future versions of the
               shell.  See also the uncomplete builtin command.

               Continues execution of the nearest enclosing while or  foreach.
               The rest of the commands on the current line are executed.

               Labels  the default case in a switch statement.  It should come
               after all case labels.

       dirs [-l] [-n|-v]
       dirs -S|-L [filename] (+)
       dirs -c (+)
               The first form prints the directory  stack.   The  top  of  the
               stack  is  at  the left and the first directory in the stack is
               the current directory.  With -l, ‘~’ or ‘~name’ in  the  output
               is  expanded  explicitly  to  home  or the pathname of the home
               directory for user name.  (+)  With  -n,  entries  are  wrapped
               before they reach the edge of the screen.  (+) With -v, entries
               are printed one per line, preceded by  their  stack  positions.
               (+) If more than one of -n or -v is given, -v takes precedence.
               -p is accepted but does nothing.

               With -S, the second form saves the directory stack to  filename
               as  a  series  of  cd  and  pushd commands.  With -L, the shell
               sources filename, which is presumably a  directory  stack  file
               saved  by  the  -S option or the savedirs mechanism.  In either
               case, dirsfile is used if filename is not given and  ~/.cshdirs
               is used if dirsfile is unset.

               Note  that  login  shells  do  the  equivalent  of ‘dirs -L’ on
               startup and, if savedirs is  set,  ‘dirs  -S’  before  exiting.
               Because  only  ~/.tcshrc is normally sourced before ~/.cshdirs,
               dirsfile should be set in ~/.tcshrc rather than ~/.login.

               The last form clears the directory stack.

       echo [-n] word ...
               Writes each word to the shell’s standard output,  separated  by
               spaces  and  terminated  with  a newline.  The echo_style shell
               variable may be set to emulate (or not) the  flags  and  escape
               sequences  of  the  BSD  and/or  System V versions of echo; see

       echotc [-sv] arg ... (+)
               Exercises the terminal capabilities (see termcap(5))  in  args.
               For  example,  ’echotc home’ sends the cursor to the home posi-
               tion, ’echotc cm 3 10’ sends it to column 3  and  row  10,  and
               ’echotc  ts  0; echo "This is a test."; echotc fs’ prints "This
               is a test."  in the status line.

               If arg is ’baud’, ’cols’, ’lines’, ’meta’ or ’tabs’, prints the
               value  of  that  capability  ("yes" or "no" indicating that the
               terminal does or does not have that capability).  One might use
               this  to  make  the  output from a shell script less verbose on
               slow terminals, or limit command output to the number of  lines
               on the screen:

                   > set history=‘echotc lines‘
                   > @ history--

               Termcap  strings may contain wildcards which will not echo cor-
               rectly.  One should use double  quotes  when  setting  a  shell
               variable  to  a terminal capability string, as in the following
               example that places the date in the status line:

                   > set tosl="‘echotc ts 0‘"
                   > set frsl="‘echotc fs‘"
                   > echo -n "$tosl";date; echo -n "$frsl"

               With -s,  nonexistent  capabilities  return  the  empty  string
               rather than causing an error.  With -v, messages are verbose.

       endsw   See  the  description  of  the  foreach,  if, switch, and while
               statements below.

       eval arg ...
               Treats the arguments as input to the  shell  and  executes  the
               resulting command(s) in the context of the current shell.  This
               is usually used to execute commands generated as the result  of
               command or variable substitution, because parsing occurs before
               these substitutions.  See tset(1) for a sample use of eval.

       exec command
               Executes the specified command in place of the current shell.

       exit [expr]
               The shell exits either with the value of the specified expr (an
               expression,  as  described under Expressions) or, without expr,
               with the value of the status variable.

       fg [%job ...]
               Brings the specified jobs (or, without arguments,  the  current
               job)  into  the  foreground,  continuing each if it is stopped.
               job may be a number, a string, ‘’, ‘%’, ‘+’ or ‘-’ as described
               under Jobs.  See also the run-fg-editor editor command.

       filetest -op file ... (+)
               Applies op (which is a file inquiry operator as described under
               File inquiry operators) to each file and returns the results as
               a space-separated list.

       foreach name (wordlist)
       end     Successively  sets the variable name to each member of wordlist
               and executes the sequence of commands between this command  and
               the  matching  end.  (Both foreach and end must appear alone on
               separate lines.)  The builtin command continue may be  used  to
               continue  the loop prematurely and the builtin command break to
               terminate it prematurely.  When this command is read  from  the
               terminal,  the loop is read once prompting with ‘foreach? ’ (or
               prompt2) before any statements in the loop  are  executed.   If
               you make a mistake typing in a loop at the terminal you can rub
               it out.

       getspath (+)
               Prints the system execution path.  (TCF only)

       getxvers (+)
               Prints the experimental version prefix.  (TCF only)

       glob wordlist
               Like echo, but no ‘\’ escapes  are  recognized  and  words  are
               delimited  by  null  characters in the output.  Useful for pro-
               grams which wish to use the shell to filename expand a list  of

       goto word
               word  is  filename and command-substituted to yield a string of
               the form ‘label’.  The shell rewinds its input as much as  pos-
               sible,  searches for a line of the form ‘label:’, possibly pre-
               ceded by blanks or tabs, and  continues  execution  after  that

               Prints  a statistics line indicating how effective the internal
               hash table has been at locating commands (and avoiding exec’s).
               An  exec  is attempted for each component of the path where the
               hash function indicates a possible hit, and in  each  component
               which does not begin with a ‘/’.

               On  machines  without vfork(2), prints only the number and size
               of hash buckets.

       history [-hTr] [n]
       history -S|-L|-M [filename] (+)
       history -c (+)
               The first form prints the history event list.  If  n  is  given
               only  the  n most recent events are printed or saved.  With -h,
               the history list is printed without leading numbers.  If -T  is
               specified,  timestamps are printed also in comment form.  (This
               can be used to produce files suitable for loading with ’history
               -L’  or  ’source  -h’.)  With -r, the order of printing is most
               recent first rather than oldest first.

               With -S, the second form saves the history  list  to  filename.
               If  the  first  word of the savehist shell variable is set to a
               number, at most that many lines are saved.  If the second  word
               of  savehist is set to ‘merge’, the history list is merged with
               the existing history file instead of replacing it (if there  is
               one)  and sorted by time stamp.  (+) Merging is intended for an
               environment like the X Window System  with  several  shells  in
               simultaneous  use.   Currently it succeeds only when the shells
               quit nicely one after another.

               With -L, the shell appends filename, which is presumably a his-
               tory  list saved by the -S option or the savehist mechanism, to
               the history list.  -M is like -L, but the contents of  filename
               are  merged  into the history list and sorted by timestamp.  In
               either case, histfile is used if  filename  is  not  given  and
               ~/.history  is  used  if  histfile  is  unset.  ‘history -L’ is
               exactly like ’source -h’ except that  it  does  not  require  a

               Note  that  login  shells  do the equivalent of ‘history -L’ on
               startup and, if savehist is set, ‘history -S’  before  exiting.
               Because  only  ~/.tcshrc is normally sourced before ~/.history,
               histfile should be set in ~/.tcshrc rather than ~/.login.

               If histlit is set, the first and second forms  print  and  save
               the literal (unexpanded) form of the history list.

               The last form clears the history list.

       hup [command] (+)
               With  command,  runs command such that it will exit on a hangup
               signal and arranges for the shell to send it  a  hangup  signal
               when  the  shell  exits.   Note that commands may set their own
               response to  hangups,  overriding  hup.   Without  an  argument
               (allowed in only a shell script), causes the shell to exit on a
               hangup for the remainder of the script.  See also  Signal  han-
               dling and the nohup builtin command.

       if (expr) command
               If  expr (an expression, as described under Expressions) evalu-
               ates true, then command is executed.  Variable substitution  on
               command happens early, at the same time it does for the rest of
               the if command.  command must  be  a  simple  command,  not  an
               alias,  a  pipeline,  a command list or a parenthesized command
               list, but it  may  have  arguments.   Input/output  redirection
               occurs  even if expr is false and command is thus not executed;
               this is a bug.

       if (expr) then
       else if (expr2) then
       endif   If the specified expr is true then the commands  to  the  first
               else are executed; otherwise if expr2 is true then the commands
               to the second else are executed, etc.  Any  number  of  else-if
               pairs are possible; only one endif is needed.  The else part is
               likewise optional.  (The words else and endif  must  appear  at
               the  beginning  of input lines; the if must appear alone on its
               input line or after an else.)

       inlib shared-library ... (+)
               Adds each shared-library to the current environment.  There  is
               no way to remove a shared library.  (Domain/OS only)

       jobs [-l]
               Lists  the active jobs.  With -l, lists process IDs in addition
               to the normal information.  On TCF systems, prints the site  on
               which each job is executing.

       kill [-s signal] %job|pid ...
       kill -l The  first  and second forms sends the specified signal (or, if
               none is given, the TERM (terminate) signal)  to  the  specified
               jobs or processes.  job may be a number, a string, ‘’, ‘%’, ‘+’
               or ‘-’ as described under Jobs.  Signals are  either  given  by
               number  or by name (as given in /usr/include/signal.h, stripped
               of the prefix ‘SIG’).  There is no  default  job;  saying  just
               ‘kill’  does not send a signal to the current job.  If the sig-
               nal being sent is TERM (terminate) or HUP  (hangup),  then  the
               job  or  process is sent a CONT (continue) signal as well.  The
               third form lists the signal names.

       limit [-h] [resource [maximum-use]]
               Limits the consumption by the current process and each  process
               it creates to not individually exceed maximum-use on the speci-
               fied resource.  If no maximum-use is given,  then  the  current
               limit is printed; if no resource is given, then all limitations
               are given.  If the -h flag is given, the hard limits  are  used
               instead  of the current limits.  The hard limits impose a ceil-
               ing on the values of the current limits.  Only  the  super-user
               may  raise  the  hard limits, but a user may lower or raise the
               current limits within the legal range.

               Controllable resources currently include (if supported  by  the

                      the  maximum  number  of  cpu-seconds to be used by each

                      the largest single file which can be created

                      the maximum growth of the data+stack region via  sbrk(2)
                      beyond the end of the program text

                      the  maximum  size  of  the automatically-extended stack

                      the size of the largest core dump that will be created

                      the maximum amount of physical memory a process may have
                      allocated to it at a given time

                      the  maximum amount of memory a process may allocate per
                      brk() system call

               descriptors or openfiles
                      the maximum number of open files for this process

                      the maximum number of threads for this process

                      the maximum size which a process may  lock  into  memory
                      using mlock(2)

                      the  maximum  number  of simultaneous processes for this
                      user id

               sbsize the maximum size of socket buffer usage for this user

               maximum-use may be given as a (floating point or integer)  num-
               ber  followed  by  a  scale  factor.  For all limits other than
               cputime the default scale is ‘k’ or ‘kilobytes’ (1024 bytes); a
               scale  factor  of  ‘m’  or  ‘megabytes’  may also be used.  For
               cputime the default scaling is ‘seconds’, while ‘m’ for minutes
               or  ‘h’ for hours, or a time of the form ‘mm:ss’ giving minutes
               and seconds may be used.

               For both resource names and scale factors, unambiguous prefixes
               of the names suffice.

       log (+) Prints  the watch shell variable and reports on each user indi-
               cated in watch who is logged in, regardless of when  they  last
               logged in.  See also watchlog.

       login   Terminates  a  login  shell,  replacing  it with an instance of
               /bin/login. This is one way to log off, included  for  compati-
               bility with sh(1).

       logout  Terminates  a  login  shell.  Especially useful if ignoreeof is

       ls-F [-switch ...] [file ...] (+)
               Lists files like ‘ls -F’, but much faster.  It identifies  each
               type of special file in the listing with a special character:

               /   Directory
               *   Executable
               #   Block device
               %   Character device
               |   Named pipe (systems with named pipes only)
               =   Socket (systems with sockets only)
               @   Symbolic link (systems with symbolic links only)
               +   Hidden  directory  (AIX  only)  or context dependent (HP/UX
               :   Network special (HP/UX only)

               If the listlinks shell variable  is  set,  symbolic  links  are
               identified  in  more detail (on only systems that have them, of

               @   Symbolic link to a non-directory
               >   Symbolic link to a directory
               &   Symbolic link to nowhere

               listlinks also slows down ls-F and  causes  partitions  holding
               files pointed to by symbolic links to be mounted.

               If  the  listflags shell variable is set to ‘x’, ‘a’ or ‘A’, or
               any combination thereof (e.g., ‘xA’), they are used as flags to
               ls-F, making it act like ‘ls -xF’, ‘ls -Fa’, ‘ls -FA’ or a com-
               bination (e.g., ‘ls -FxA’).  On machines where ‘ls -C’  is  not
               the default, ls-F acts like ‘ls -CF’, unless listflags contains
               an ‘x’, in which case it acts like ‘ls -xF’.  ls-F  passes  its
               arguments  to  ls(1)  if it is given any switches, so ‘alias ls
               ls-F’ generally does the right thing.

               The ls-F builtin can list files using different colors  depend-
               ing  on the filetype or extension.  See the color tcsh variable
               and the LS_COLORS environment variable.

       migrate [-site] pid|%jobid ... (+)
       migrate -site (+)
               The first form migrates the process or job to the  site  speci-
               fied  or  the  default site determined by the system path.  The
               second form is equivalent to ‘migrate -site  $$’:  it  migrates
               the current process to the specified site.  Migrating the shell
               itself can cause unexpected behavior, because  the  shell  does
               not like to lose its tty.  (TCF only)

       newgrp [-] group (+)
               Equivalent  to ‘exec newgrp’; see newgrp(1).  Available only if
               the shell was so compiled; see the version shell variable.

       nice [+number] [command]
               Sets the scheduling priority for the shell to number, or, with-
               out  number, to 4.  With command, runs command at the appropri-
               ate priority.  The greater the number, the less cpu the process
               gets.   The  super-user  may specify negative priority by using
               ‘nice -number ...’.  Command is always executed in a sub-shell,
               and the restrictions placed on commands in simple if statements

       nohup [command]
               With command, runs command such that it will ignore hangup sig-
               nals.   Note  that  commands  may  set  their  own  response to
               hangups, overriding nohup.  Without  an  argument  (allowed  in
               only  a  shell  script), causes the shell to ignore hangups for
               the remainder of the script.  See also Signal handling and  the
               hup builtin command.

       notify [%job ...]
               Causes  the  shell  to  notify the user asynchronously when the
               status of any of the specified jobs (or, without %job, the cur-
               rent  job) changes, instead of waiting until the next prompt as
               is usual.  job may be a number, a string, ‘’, ‘%’, ‘+’  or  ‘-’
               as described under Jobs.  See also the notify shell variable.

       onintr [-|label]
               Controls  the action of the shell on interrupts.  Without argu-
               ments, restores the default action of the shell on  interrupts,
               which  is to terminate shell scripts or to return to the termi-
               nal command input level.  With ‘-’, causes all interrupts to be
               ignored.   With  label,  causes  the  shell  to execute a ‘goto
               label’ when an interrupt is received or a child process  termi-
               nates because it was interrupted.

               onintr  is ignored if the shell is running detached and in sys-
               tem startup files (see FILES), where  interrupts  are  disabled

       popd [-p] [-l] [-n|-v] [+n]
               Without  arguments, pops the directory stack and returns to the
               new top directory.  With a number ‘+n’, discards the n’th entry
               in the stack.

               Finally,  all  forms  of  popd print the final directory stack,
               just like dirs.  The pushdsilent shell variable can be  set  to
               prevent  this and the -p flag can be given to override pushdsi-
               lent.  The -l, -n and -v flags have the same effect on popd  as
               on dirs.  (+)

       printenv [name] (+)
               Prints  the  names  and values of all environment variables or,
               with name, the value of the environment variable name.

       pushd [-p] [-l] [-n|-v] [name|+n]
               Without arguments, exchanges the top two elements of the direc-
               tory  stack.   If  pushdtohome  is set, pushd without arguments
               does ‘pushd ~’, like cd.  (+) With  name,  pushes  the  current
               working directory onto the directory stack and changes to name.
               If name is ‘-’ it is interpreted as the previous working direc-
               tory (see Filename substitution).  (+) If dunique is set, pushd
               removes any instances of name from the stack before pushing  it
               onto  the  stack.  (+) With a number ‘+n’, rotates the nth ele-
               ment of the directory stack around to be the  top  element  and
               changes  to  it.   If  dextract  is  set,  however,  ‘pushd +n’
               extracts the nth directory, pushes it onto the top of the stack
               and changes to it.  (+)

               Finally,  all  forms  of pushd print the final directory stack,
               just like dirs.  The pushdsilent shell variable can be  set  to
               prevent  this and the -p flag can be given to override pushdsi-
               lent.  The -l, -n and -v flags have the same effect on pushd as
               on dirs.  (+)

       rehash  Causes  the internal hash table of the contents of the directo-
               ries in the path variable to be recomputed.  This is needed  if
               new  commands  are  added  to directories in path while you are
               logged in.  This should be necessary only if you  add  commands
               to  one  of  your  own  directories, or if a systems programmer
               changes the contents of one of the  system  directories.   Also
               flushes the cache of home directories built by tilde expansion.

       repeat count command
               The specified command, which is subject to  the  same  restric-
               tions  as  the  command  in the one line if statement above, is
               executed count times.  I/O  redirections  occur  exactly  once,
               even if count is 0.

       rootnode //nodename (+)
               Changes  the rootnode to //nodename, so that ‘/’ will be inter-
               preted as ‘//nodename’.  (Domain/OS only)

       sched (+)
       sched [+]hh:mm command (+)
       sched -n (+)
               The first form prints  the  scheduled-event  list.   The  sched
               shell  variable  may  be  set to define the format in which the
               scheduled-event list is printed.  The second form adds  command
               to the scheduled-event list.  For example,

                   > sched 11:00 echo It\’s eleven o\’clock.

               causes  the shell to echo ‘It’s eleven o’clock.’ at 11 AM.  The
               time may be in 12-hour AM/PM format

                   > sched 5pm set prompt=’[%h] It\’s after 5; go home: >’

               or may be relative to the current time:

                   > sched +2:15 /usr/lib/uucp/uucico -r1 -sother

               A relative time specification may not use  AM/PM  format.   The
               third form removes item n from the event list:

                   > sched
                        1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother
                        2   Wed Apr  4 17:00  set prompt=[%h] It’s after 5; go
                   home: >
                   > sched -2
                   > sched
                        1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother

               A command in the scheduled-event list is executed  just  before
               the  first prompt is printed after the time when the command is
               scheduled.  It is possible to miss the exact time when the com-
               mand  is  to be run, but an overdue command will execute at the
               next prompt.  A command which comes  due  while  the  shell  is
               waiting  for user input is executed immediately.  However, nor-
               mal operation of an already-running command will not be  inter-
               rupted so that a scheduled-event list element may be run.

               This  mechanism  is  similar to, but not the same as, the at(1)
               command on some Unix systems.  Its major disadvantage  is  that
               it  may  not  run a command at exactly the specified time.  Its
               major advantage is that because sched runs  directly  from  the
               shell,  it  has access to shell variables and other structures.
               This provides a mechanism for changing one’s  working  environ-
               ment based on the time of day.

       set name ...
       set name=word ...
       set [-r] [-f|-l] name=(wordlist) ... (+)
       set name[index]=word ...
       set -r (+)
       set -r name ... (+)
       set -r name=word ... (+)
               The  first  form  of  the command prints the value of all shell
               variables.  Variables which contain more  than  a  single  word
               print  as a parenthesized word list.  The second form sets name
               to the null string.  The third form sets  name  to  the  single
               word.   The  fourth  form  sets  name  to  the list of words in
               wordlist.  In all cases  the  value  is  command  and  filename
               expanded.   If -r is specified, the value is set read-only.  If
               -f or -l are specified, set only  unique  words  keeping  their
               order.   -f  prefers the first occurrence of a word, and -l the
               last.  The fifth form sets the index’th component  of  name  to
               word;  this component must already exist.  The sixth form lists
               only the names of all shell variables that are read-only.   The
               seventh  form  makes  name  read-only,  whether or not it has a
               value.  The second form sets name  to  the  null  string.   The
               eighth  form is the same as the third form, but make name read-
               only at the same time.

               These arguments can be repeated to set  and/or  make  read-only
               multiple  variables  in  a  single set command.  Note, however,
               that variable expansion happens for all  arguments  before  any
               setting  occurs.   Note  also  that ‘=’ can be adjacent to both
               name and word or separated from both by whitespace, but  cannot
               be  adjacent  to  only  one  or  the other.  See also the unset
               builtin command.

       setenv [name [value]]
               Without arguments, prints the names and values of all  environ-
               ment variables.  Given name, sets the environment variable name
               to value or, without value, to the null string.

       setpath path (+)
               Equivalent to setpath(1).  (Mach only)

       setspath LOCAL|site|cpu ... (+)
               Sets the system execution path.  (TCF only)

       settc cap value (+)
               Tells the shell to believe that the terminal capability cap (as
               defined in termcap(5)) has the value value.  No sanity checking
               is done.  Concept terminal users may have to ‘settc xn  no’  to
               get proper wrapping at the rightmost column.

       setty [-d|-q|-x] [-a] [[+|-]mode] (+)
               Controls  which  tty  modes (see Terminal management) the shell
               does not allow to change.  -d, -q or -x tells setty to  act  on
               the ‘edit’, ‘quote’ or ‘execute’ set of tty modes respectively;
               without -d, -q or -x, ‘execute’ is used.

               Without other arguments, setty lists the modes  in  the  chosen
               set  which are fixed on (‘+mode’) or off (‘-mode’).  The avail-
               able modes, and thus the display, vary from system  to  system.
               With  -a,  lists all tty modes in the chosen set whether or not
               they are fixed.  With +mode, -mode or mode, fixes  mode  on  or
               off  or removes control from mode in the chosen set.  For exam-
               ple, ‘setty +echok echoe’ fixes ‘echok’ mode on and allows com-
               mands  to  turn  ‘echoe’ mode on or off, both when the shell is
               executing commands.

       setxvers [string] (+)
               Set the experimental version prefix to string, or removes it if
               string is omitted.  (TCF only)

       shift [variable]
               Without  arguments,  discards argv[1] and shifts the members of
               argv to the left.  It is an error for argv not to be set or  to
               have  less than one word as value.  With variable, performs the
               same function on variable.

       source [-h] name [args ...]
               The shell reads and executes commands from name.  The  commands
               are  not  placed  on  the history list.  If any args are given,
               they are placed in argv.  (+) source commands may be nested; if
               they  are  nested  too  deeply  the  shell  may run out of file
               descriptors.  An error in a source at any level terminates  all
               nested  source  commands.   With -h, commands are placed on the
               history list instead of being executed, much like ‘history -L’.

       stop %job|pid ...
               Stops  the  specified  jobs or processes which are executing in
               the background.  job may be a number, a string, ‘’, ‘%’, ‘+’ or
               ‘-’  as  described under Jobs.  There is no default job; saying
               just ‘stop’ does not stop the current job.

       suspend Causes the shell to stop in its tracks, much as if it had  been
               sent  a  stop  signal with ^Z.  This is most often used to stop
               shells started by su(1).

       switch (string)
       case str1:
       endsw   Each case label is successively matched, against the  specified
               string  which is first command and filename expanded.  The file
               metacharacters ‘*’, ‘?’ and ‘[...]’  may be used  in  the  case
               labels,  which  are  variable  expanded.  If none of the labels
               match before a ‘default’ label is  found,  then  the  execution
               begins  after  the  default  label.   Each  case  label and the
               default label must appear at the beginning of a line.  The com-
               mand  breaksw  causes  execution  to  continue after the endsw.
               Otherwise control may fall  through  case  labels  and  default
               labels  as  in C.  If no label matches and there is no default,
               execution continues after the endsw.

       telltc (+)
               Lists the values of all terminal capabilities (see termcap(5)).

       termname [terminal type] (+)
               Tests if terminal type (or the current value of TERM if no ter-
               minal type is given) has an entry in the  hosts  termcap(5)  or
               terminfo(5)  database.  Prints  the terminal type to stdout and
               returns 0 if an entry is present otherwise returns 1.

       time [command]
               Executes command (which must be a simple command, not an alias,
               a pipeline, a command list or a parenthesized command list) and
               prints a time summary as described under the time variable.  If
               necessary,  an extra shell is created to print the time statis-
               tic when the command completes.  Without command, prints a time
               summary for the current shell and its children.

       umask [value]
               Sets  the file creation mask to value, which is given in octal.
               Common values for the mask are 002, giving all  access  to  the
               group  and  read  and execute access to others, and 022, giving
               read and execute access  to  the  group  and  others.   Without
               value, prints the current file creation mask.

       unalias pattern
               Removes  all  aliases  whose  names match pattern.  ‘unalias *’
               thus removes all aliases.  It is not an error for nothing to be

       uncomplete pattern (+)
               Removes all completions whose names match pattern.  ‘uncomplete
               *’ thus removes all completions.  It is not an error for  noth-
               ing to be uncompleted.

       unhash  Disables  use  of  the internal hash table to speed location of
               executed programs.

       universe universe (+)
               Sets the universe to universe.  (Masscomp/RTU only)

       unlimit [-h] [resource]
               Removes the limitation on resource or, if no resource is speci-
               fied,  all  resource  limitations.   With -h, the corresponding
               hard limits are removed.  Only  the  super-user  may  do  this.
               Note  that  unlimit may not exit successful, since most systems
               do not allow descriptors to be unlimited.

       unset pattern
               Removes all variables whose names match  pattern,  unless  they
               are  read-only.   ‘unset  *’  thus removes all variables unless
               they are read-only; this is a bad idea.  It is not an error for
               nothing to be unset.

       unsetenv pattern
               Removes  all  environment  variables whose names match pattern.
               ‘unsetenv *’ thus removes all environment variables; this is  a
               bad idea.  It is not an error for nothing to be unsetenved.

       ver [systype [command]] (+)
               Without  arguments, prints SYSTYPE.  With systype, sets SYSTYPE
               to systype.  With systype and command, executes  command  under
               systype.   systype  may  be  ‘bsd4.3’  or ‘sys5.3’.  (Domain/OS

       wait    The shell waits for all  background  jobs.   If  the  shell  is
               interactive,  an  interrupt will disrupt the wait and cause the
               shell to print the names and job  numbers  of  all  outstanding

       warp universe (+)
               Sets the universe to universe.  (Convex/OS only)

       watchlog (+)
               An  alternate  name for the log builtin command (q.v.).  Avail-
               able only if the shell was so compiled; see the  version  shell

       where command (+)
               Reports  all  known  instances  of  command, including aliases,
               builtins and executables in path.

       which command (+)
               Displays the command that will be executed by the  shell  after
               substitutions,  path  searching,  etc.   The builtin command is
               just like which(1), but it correctly reports tcsh  aliases  and
               builtins  and  is  10 to 100 times faster.  See also the which-
               command editor command.

       while (expr)
       end     Executes the commands between the while and  the  matching  end
               while  expr  (an  expression,  as  described under Expressions)
               evaluates non-zero.  while and end must appear alone  on  their
               input  lines.   break  and continue may be used to terminate or
               continue the loop prematurely.  If the input is a terminal, the
               user  is prompted the first time through the loop as with fore-

   Special aliases (+)
       If set, each of these aliases executes automatically at  the  indicated
       time.  They are all initially undefined.

       beepcmd Runs when the shell wants to ring the terminal bell.

       cwdcmd  Runs  after every change of working directory.  For example, if
               the user is working on an X window system using xterm(1) and  a
               re-parenting  window  manager  that supports title bars such as
               twm(1) and does

                   > alias cwdcmd  ’echo -n "^[]2;${HOST}:$cwd ^G"’

               then the shell will change the title of the running xterm(1) to
               be  the name of the host, a colon, and the full current working
               directory.  A fancier way to do that is

                   >          alias          cwdcmd          ’echo          -n

               This  will  put the hostname and working directory on the title
               bar but only the hostname in the icon manager menu.

               Note that putting a cd, pushd or popd in cwdcmd  may  cause  an
               infinite loop.  It is the author’s opinion that anyone doing so
               will get what they deserve.

       jobcmd  Runs before each command gets executed,  or  when  the  command
               changes  state.   This  is  similar to postcmd, but it does not
               print builtins.

                   > alias jobcmd  ’echo -n "^[]2\;\!#^G"’

               then executing vi foo.c will put  the  command  string  in  the
               xterm title bar.

               Invoked  by  the run-help editor command.  The command name for
               which help is sought is passed as sole argument.  For  example,
               if one does

                   > alias helpcommand ’\!:1 --help’

               then  the  help  display of the command itself will be invoked,
               using the GNU help calling convention.  Currently there  is  no
               easy  way to account for various calling conventions (e.g., the
               customary Unix ‘-h’), except by using a table of many commands.

               Runs  every  tperiod minutes.  This provides a convenient means
               for checking on common but infrequent changes such as new mail.
               For example, if one does

                   > set tperiod = 30
                   > alias periodic checknews

               then  the checknews(1) program runs every 30 minutes.  If peri-
               odic is set but tperiod is unset or set to 0, periodic  behaves
               like precmd.

       precmd  Runs  just  before each prompt is printed.  For example, if one

                   > alias precmd date

               then date(1) runs just before the shell prompts for  each  com-
               mand.  There are no limits on what precmd can be set to do, but
               discretion should be used.

       postcmd Runs before each command gets executed.

                   > alias postcmd  ’echo -n "^[]2\;\!#^G"’

               then executing vi foo.c will put  the  command  string  in  the
               xterm title bar.

       shell   Specifies  the  interpreter for executable scripts which do not
               themselves specify an interpreter.  The first word should be  a
               full  path name to the desired interpreter (e.g., ‘/bin/csh’ or

   Special shell variables
       The variables described in this section have  special  meaning  to  the

       The  shell  sets  addsuffix,  argv,  autologout,  csubstnonl,  command,
       echo_style,  edit,  gid,  group,  home,  loginsh,  oid,  path,  prompt,
       prompt2,  prompt3, shell, shlvl, tcsh, term, tty, uid, user and version
       at startup; they do not change thereafter unless changed by  the  user.
       The  shell  updates  cwd,  dirstack, owd and status when necessary, and
       sets logout on logout.

       The shell synchronizes afsuser, group, home, path, shlvl, term and user
       with the environment variables of the same names: whenever the environ-
       ment variable changes the shell changes the corresponding  shell  vari-
       able  to match (unless the shell variable is read-only) and vice versa.
       Note that although cwd and PWD have identical meanings,  they  are  not
       synchronized in this manner, and that the shell automatically intercon-
       verts the different formats of path and PATH.

       addsuffix (+)
               If set, filename completion adds ‘/’ to the end of  directories
               and  a  space  to the end of normal files when they are matched
               exactly.  Set by default.

       afsuser (+)
               If set, autologout’s autolock feature uses its value instead of
               the local username for kerberos authentication.

       ampm (+)
               If set, all times are shown in 12-hour AM/PM format.

       argv    The  arguments  to  the shell.  Positional parameters are taken
               from argv, i.e., ‘$1’ is replaced by ‘$argv[1]’, etc.   Set  by
               default, but usually empty in interactive shells.

       autocorrect (+)
               If  set, the spell-word editor command is invoked automatically
               before each completion attempt.

       autoexpand (+)
               If set, the expand-history editor command is invoked  automati-
               cally before each completion attempt.

       autolist (+)
               If set, possibilities are listed after an ambiguous completion.
               If set to ‘ambiguous’, possibilities are listed  only  when  no
               new characters are added by completion.

       autologout (+)
               The  first  word  is the number of minutes of inactivity before
               automatic logout.  The optional second word is  the  number  of
               minutes of inactivity before automatic locking.  When the shell
               automatically logs out, it prints ‘auto-logout’, sets the vari-
               able logout to ‘automatic’ and exits.  When the shell automati-
               cally locks, the user is required to enter his password to con-
               tinue  working.   Five  incorrect  attempts result in automatic
               logout.  Set to ‘60’ (automatic logout after 60 minutes, and no
               locking)  by  default in login and superuser shells, but not if
               the shell thinks it is running under a window system (i.e., the
               DISPLAY  environment  variable is set), the tty is a pseudo-tty
               (pty) or the shell was not so compiled (see the  version  shell
               variable).  See also the afsuser and logout shell variables.

       backslash_quote (+)
               If set, backslashes (‘\’) always quote ‘\’, ‘’’, and ‘"’.  This
               may make complex quoting tasks easier, but it can cause  syntax
               errors in csh(1) scripts.

       catalog The  file  name  of  the  message  catalog.   If  set, tcsh use
               ‘tcsh.${catalog}’ as  a  message  catalog  instead  of  default

       cdpath  A list of directories in which cd should search for subdirecto-
               ries if they aren’t found in the current directory.

       color   If set, it enables color display for the builtin  ls-F  and  it
               passes  --color=auto  to  ls.   Alternatively, it can be set to
               only ls-F or only ls to enable color to only one command.  Set-
               ting it to nothing is equivalent to setting it to (ls-F ls).

               If set, it enables color escape sequence for NLS message files.
               And display colorful NLS messages.

       command (+)
               If set, the command which was passed to the shell with  the  -c
               flag (q.v.).

       complete (+)
               If  set to ‘enhance’, completion 1) ignores case and 2) consid-
               ers periods, hyphens and underscores (‘.’, ‘-’ and ‘_’)  to  be
               word  separators  and hyphens and underscores to be equivalent.
               If set to ‘igncase’, the completion becomes case insensitive.

       continue (+)
               If set to a list of  commands,  the  shell  will  continue  the
               listed commands, instead of starting a new one.

       continue_args (+)
               Same as continue, but the shell will execute:

                   echo ‘pwd‘ $argv > ~/.<cmd>_pause; %<cmd>

       correct (+)
               If set to ‘cmd’, commands are automatically spelling-corrected.
               If set to ‘complete’, commands are automatically completed.  If
               set to ‘all’, the entire command line is corrected.

       csubstnonl (+)
               If  set,  newlines and carriage returns in command substitution
               are replaced by spaces.  Set by default.

       cwd     The full pathname of  the  current  directory.   See  also  the
               dirstack and owd shell variables.

       dextract (+)
               If  set,  ‘pushd +n’ extracts the nth directory from the direc-
               tory stack rather than rotating it to the top.

       dirsfile (+)
               The default location in which ‘dirs -S’ and ‘dirs -L’ look  for
               a  history  file.   If unset, ~/.cshdirs is used.  Because only
               ~/.tcshrc  is  normally  sourced  before  ~/.cshdirs,  dirsfile
               should be set in ~/.tcshrc rather than ~/.login.

       dirstack (+)
               An  array  of  all  the  directories  on  the  directory stack.
               ‘$dirstack[1]’ is the current working directory, ‘$dirstack[2]’
               the  first  directory on the stack, etc.  Note that the current
               working directory is ‘$dirstack[1]’ but ‘=0’ in directory stack
               substitutions,  etc.   One  can change the stack arbitrarily by
               setting dirstack, but the first element  (the  current  working
               directory)  is  always correct.  See also the cwd and owd shell

       dspmbyte (+)
               Has an affect iff ’dspm’ is listed as part of the version shell
               variable.  If set to ‘euc’, it enables display and editing EUC-
               kanji(Japanese) code.  If set to ‘sjis’, it enables display and
               editing Shift-JIS(Japanese) code.  If set to ‘big5’, it enables
               display and editing Big5(Chinese) code.  If set to  ‘utf8’,  it
               enables  display and editing Utf8(Unicode) code.  If set to the
               following format, it enables display and  editing  of  original
               multi-byte code format:

                   > set dspmbyte = 0000....(256 bytes)....0000

               The table requires just 256 bytes.  Each character of 256 char-
               acters corresponds (from left to  right)  to  the  ASCII  codes
               0x00,  0x01,  ...  0xff.  Each character is set to number 0,1,2
               and 3.  Each number has the following meaning:
                 0 ... not used for multi-byte characters.
                 1 ... used for the first byte of a multi-byte character.
                 2 ... used for the second byte of a multi-byte character.
                 3 ... used for both the first  byte  and  second  byte  of  a
               multi-byte character.

               If  set  to  ‘001322’,  the  first character (means 0x00 of the
               ASCII code) and second character (means 0x01 of ASCII code) are
               set  to  ‘0’.   Then, it is not used for multi-byte characters.
               The 3rd character (0x02) is set to ’1’, indicating that  it  is
               used  for  the  first  byte of a multi-byte character.  The 4th
               character(0x03) is set ’3’.  It is used for both the first byte
               and the second byte of a multi-byte character.  The 5th and 6th
               characters (0x04,0x05) are set to ’2’, indicating that they are
               used for the second byte of a multi-byte character.

               The GNU fileutils version of ls cannot display multi-byte file-
               names without the -N ( --literal ) option.   If you  are  using
               this version, set the second word of dspmbyte to "ls".  If not,
               for example, "ls-F -l" cannot display multi-byte filenames.

               This variable can only be used if KANJI and DSPMBYTE  has  been
               defined at compile time.

       dunique (+)
               If  set,  pushd  removes  any  instances of name from the stack
               before pushing it onto the stack.

       echo    If set, each command with its arguments is echoed  just  before
               it  is executed.  For non-builtin commands all expansions occur
               before echoing.  Builtin commands are echoed before command and
               filename  substitution,  because  these  substitutions are then
               done selectively.  Set by the -x command line option.

       echo_style (+)
               The style of the echo builtin.  May be set to

               bsd     Don’t echo a newline if the first argument is ‘-n’.
               sysv    Recognize backslashed escape sequences in echo strings.
               both    Recognize  both  the  ‘-n’  flag and backslashed escape
                       sequences; the default.
               none    Recognize neither.

               Set by default to the local system default.  The BSD and System
               V  options are described in the echo(1) man pages on the appro-
               priate systems.

       edit (+)
               If set, the command-line editor is used.   Set  by  default  in
               interactive shells.

       ellipsis (+)
               If set, the ‘%c’/‘%.’ and ‘%C’ prompt sequences (see the prompt
               shell variable) indicate skipped directories with  an  ellipsis
               (‘...’)  instead of ‘/<skipped>’.

       fignore (+)
               Lists file name suffixes to be ignored by completion.

       filec   In tcsh, completion is always used and this variable is ignored
               by default. If edit is unset, then the traditional csh  comple-
               tion is used.  If set in csh, filename completion is used.

       gid (+) The user’s real group ID.

       group (+)
               The user’s group name.

               A  string value determining the characters used in History sub-
               stitution (q.v.).  The first character of its value is used  as
               the history substitution character, replacing the default char-
               acter ‘!’.  The second character  of  its  value  replaces  the
               character ‘^’ in quick substitutions.

       histdup (+)
               Controls handling of duplicate entries in the history list.  If
               set to ‘all’ only unique history events are entered in the his-
               tory  list.  If set to ‘prev’ and the last history event is the
               same as the current command, then the current  command  is  not
               entered  in  the history.  If set to ‘erase’ and the same event
               is found in the history list, that old event  gets  erased  and
               the  current one gets inserted.  Note that the ‘prev’ and ‘all’
               options renumber history events so there are no gaps.

       histfile (+)
               The default location in which ‘history  -S’  and  ‘history  -L’
               look  for a history file.  If unset, ~/.history is used.  hist-
               file is useful when sharing the  same  home  directory  between
               different  machines,  or when saving separate histories on dif-
               ferent terminals.  Because only ~/.tcshrc is  normally  sourced
               before  ~/.history,  histfile should be set in ~/.tcshrc rather
               than ~/.login.

       histlit (+)
               If set, builtin and editor commands and the savehist  mechanism
               use the literal (unexpanded) form of lines in the history list.
               See also the toggle-literal-history editor command.

       history The first word indicates the number of history events to  save.
               The optional second word (+) indicates the format in which his-
               tory is printed; if not given,  ‘%h\t%T\t%R\n’  is  used.   The
               format  sequences  are  described  below under prompt; note the
               variable meaning of ‘%R’.  Set to ‘100’ by default.

       home    Initialized to the home directory of the invoker.  The filename
               expansion of ‘~’ refers to this variable.

               If  set  to  the  empty string or ‘0’ and the input device is a
               terminal, the end-of-file command  (usually  generated  by  the
               user by typing ‘^D’ on an empty line) causes the shell to print
               ‘Use "exit" to leave tcsh.’ instead of exiting.  This  prevents
               the  shell  from  accidentally being killed.  Historically this
               setting exited after 26  successive  EOF’s  to  avoid  infinite
               loops.   If set to a number n, the shell ignores n - 1 consecu-
               tive end-of-files and exits on the nth.  (+) If unset,  ‘1’  is
               used, i.e., the shell exits on a single ‘^D’.

       implicitcd (+)
               If set, the shell treats a directory name typed as a command as
               though it were a request to change to that directory.   If  set
               to  verbose,  the change of directory is echoed to the standard
               output.  This behavior is inhibited  in  non-interactive  shell
               scripts,  or  for  command  strings  with  more  than one word.
               Changing directory takes precedence over executing a like-named
               command,  but  it is done after alias substitutions.  Tilde and
               variable expansions work as expected.

       inputmode (+)
               If set to ‘insert’ or ‘overwrite’, puts the  editor  into  that
               input mode at the beginning of each line.

       killdup (+)
               Controls  handling  of  duplicate entries in the kill ring.  If
               set to ‘all’ only unique strings are entered in the kill  ring.
               If  set to ‘prev’ and the last killed string is the same as the
               current killed string, then the current string is  not  entered
               in the ring.  If set to ‘erase’ and the same string is found in
               the kill ring, the old string is erased and the current one  is

       killring (+)
               Indicates  the number of killed strings to keep in memory.  Set
               to ‘30’ by default.  If unset or set  to  less  than  ‘2’,  the
               shell  will only keep the most recently killed string.  Strings
               are put in the killring by  the  editor  commands  that  delete
               (kill)  strings  of text, e.g. backward-delete-word, kill-line,
               etc, as well as the copy-region-as-kill command.  The yank edi-
               tor  command will yank the most recently killed string into the
               command-line, while yank-pop (see Editor commands) can be  used
               to yank earlier killed strings.

       listflags (+)
               If  set  to  ‘x’, ‘a’ or ‘A’, or any combination thereof (e.g.,
               ‘xA’), they are used as flags to ls-F, making it act  like  ‘ls
               -xF’,  ‘ls  -Fa’,  ‘ls -FA’ or a combination (e.g., ‘ls -FxA’):
               ‘a’ shows all files (even if they start with a ‘.’), ‘A’  shows
               all  files  but  ‘.’  and ‘..’, and ‘x’ sorts across instead of
               down.  If the second word of listflags is set, it  is  used  as
               the path to ‘ls(1)’.

       listjobs (+)
               If set, all jobs are listed when a job is suspended.  If set to
               ‘long’, the listing is in long format.

       listlinks (+)
               If set, the ls-F builtin command shows  the  type  of  file  to
               which each symbolic link points.

       listmax (+)
               The  maximum number of items which the list-choices editor com-
               mand will list without asking first.

       listmaxrows (+)
               The maximum number of rows of items which the list-choices edi-
               tor command will list without asking first.

       loginsh (+)
               Set  by the shell if it is a login shell.  Setting or unsetting
               it within a shell has no effect.  See also shlvl.

       logout (+)
               Set by the shell to ‘normal’ before  a  normal  logout,  ‘auto-
               matic’  before  an  automatic logout, and ‘hangup’ if the shell
               was killed by a hangup signal (see Signal handling).  See  also
               the autologout shell variable.

       mail    The  names  of  the  files or directories to check for incoming
               mail, separated by whitespace, and  optionally  preceded  by  a
               numeric  word.   Before  each prompt, if 10 minutes have passed
               since the last check, the shell checks each file and says  ‘You
               have new mail.’ (or, if mail contains multiple files, ‘You have
               new mail in name.’) if the filesize is  greater  than  zero  in
               size  and has a modification time greater than its access time.

               If you are in a login shell, then  no  mail  file  is  reported
               unless  it  has  been  modified  after  the  time the shell has
               started up, to prevent  redundant  notifications.   Most  login
               programs  will  tell  you whether or not you have mail when you
               log in.

               If a file specified in mail is  a  directory,  the  shell  will
               count  each  file  within that directory as a separate message,
               and will report ‘You have n mails.’ or ‘You  have  n  mails  in
               name.’  as appropriate.  This functionality is provided primar-
               ily for those systems which store mail in this manner, such  as
               the Andrew Mail System.

               If the first word of mail is numeric it is taken as a different
               mail checking interval, in seconds.

               Under very rare circumstances, the shell may report  ‘You  have
               mail.’ instead of ‘You have new mail.’

       matchbeep (+)
               If   set  to  ‘never’,  completion  never  beeps.   If  set  to
               ‘nomatch’, it beeps only when there is no  match.   If  set  to
               ‘ambiguous’,  it beeps when there are multiple matches.  If set
               to ‘notunique’, it beeps when there  is  one  exact  and  other
               longer matches.  If unset, ‘ambiguous’ is used.

       nobeep (+)
               If  set, beeping is completely disabled.  See also visiblebell.

               If set, restrictions are placed on output redirection to insure
               that  files  are not accidentally destroyed and that ‘>>’ redi-
               rections  refer  to  existing  files,  as  described   in   the
               Input/output section.

       noding  If  set,  disable  the  printing  of ‘DING!’ in the prompt time
               specifiers at the change of hour.

       noglob  If set, Filename substitution and Directory stack  substitution
               (q.v.)  are  inhibited.   This  is most useful in shell scripts
               which do not deal with filenames, or after a list of  filenames
               has been obtained and further expansions are not desirable.

       nokanji (+)
               If  set  and  the  shell  supports Kanji (see the version shell
               variable), it is disabled so that the meta key can be used.

               If set, a Filename substitution or Directory stack substitution
               (q.v.)  which  does  not  match  any  existing  files  is  left
               untouched rather than causing an error.  It is still  an  error
               for  the  substitution  to  be  malformed, e.g., ‘echo [’ still
               gives an error.

       nostat (+)
               A list of directories (or glob-patterns  which  match  directo-
               ries;  see  Filename substitution) that should not be stat(2)ed
               during a completion operation.  This is usually used to exclude
               directories  which  take  too much time to stat(2), for example

       notify  If set, the shell  announces  job  completions  asynchronously.
               The  default is to present job completions just before printing
               a prompt.

       oid (+) The user’s real organization ID.  (Domain/OS only)

       owd (+) The old working directory, equivalent to the ‘-’ used by cd and
               pushd.  See also the cwd and dirstack shell variables.

       path    A list of directories in which to look for executable commands.
               A null word specifies the current directory.  If  there  is  no
               path  variable then only full path names will execute.  path is
               set by the shell at startup from the PATH environment  variable
               or, if PATH does not exist, to a system-dependent default some-
               thing like ‘(/usr/local/bin /usr/bsd /bin  /usr/bin  .)’.   The
               shell  may  put  ‘.’  first or last in path or omit it entirely
               depending on how it was compiled; see the version  shell  vari-
               able.   A shell which is given neither the -c nor the -t option
               hashes the contents of the directories in  path  after  reading
               ~/.tcshrc  and each time path is reset.  If one adds a new com-
               mand to a directory in path while the shell is active, one  may
               need to do a rehash for the shell to find it.

       printexitvalue (+)
               If set and an interactive program exits with a non-zero status,
               the shell prints ‘Exit status’.

       prompt  The string which is printed before reading  each  command  from
               the  terminal.  prompt may include any of the following format-
               ting sequences (+), which are replaced by  the  given  informa-

               %/  The current working directory.
               %~  The  current  working directory, but with one’s home direc-
                   tory represented by ‘~’ and other users’  home  directories
                   represented   by  ‘~user’  as  per  Filename  substitution.
                   ‘~user’ substitution happens only if the shell has  already
                   used ‘~user’ in a pathname in the current session.
               %c[[0]n], %.[[0]n]
                   The trailing component of the current working directory, or
                   n trailing components if a digit n is given.  If  n  begins
                   with  ‘0’,  the  number  of  skipped components precede the
                   trailing component(s) in the  format  ‘/<skipped>trailing’.
                   If  the  ellipsis shell variable is set, skipped components
                   are  represented  by  an  ellipsis  so  the  whole  becomes
                   ‘...trailing’.   ‘~’ substitution is done as in ‘%~’ above,
                   but the ‘~’ component is  ignored  when  counting  trailing
               %C  Like %c, but without ‘~’ substitution.
               %h, %!, !
                   The current history event number.
               %M  The full hostname.
               %m  The hostname up to the first ‘.’.
               %S (%s)
                   Start (stop) standout mode.
               %B (%b)
                   Start (stop) boldfacing mode.
               %U (%u)
                   Start (stop) underline mode.
               %t, %@
                   The time of day in 12-hour AM/PM format.
               %T  Like  ‘%t’,  but  in 24-hour format (but see the ampm shell
               %p  The ‘precise’ time of day in  12-hour  AM/PM  format,  with
               %P  Like  ‘%p’,  but  in 24-hour format (but see the ampm shell
               \c  c is parsed as in bindkey.
               ^c  c is parsed as in bindkey.
               %%  A single ‘%’.
               %n  The user name.
               %j  The number of jobs.
               %d  The weekday in ‘Day’ format.
               %D  The day in ‘dd’ format.
               %w  The month in ‘Mon’ format.
               %W  The month in ‘mm’ format.
               %y  The year in ‘yy’ format.
               %Y  The year in ‘yyyy’ format.
               %l  The shell’s tty.
               %L  Clears from the end of the prompt to end of the display  or
                   the end of the line.
               %$  Expands  the shell or environment variable name immediately
                   after the ‘$’.
               %#  ‘>’ (or the first character of the promptchars shell  vari-
                   able)  for  normal  users,  ‘#’ (or the second character of
                   promptchars) for the superuser.
                   Includes string as a literal escape sequence.  It should be
                   used only to change terminal attributes and should not move
                   the cursor location.  This cannot be the last  sequence  in
               %?  The  return  code  of  the command executed just before the
               %R  In prompt2, the status of the parser.  In prompt3, the cor-
                   rected string.  In history, the history string.

               ‘%B’,  ‘%S’, ‘%U’ and ‘%{string%}’ are available in only eight-
               bit-clean shells; see the version shell variable.

               The bold, standout and underline sequences are  often  used  to
               distinguish a superuser shell.  For example,

                   > set prompt = "%m [%h] %B[%@]%b [%/] you rang? "
                   tut [37] [2:54pm] [/usr/accts/sys] you rang? _

               If  ‘%t’,  ‘%@’, ‘%T’, ‘%p’, or ‘%P’ is used, and noding is not
               set, then print ‘DING!’ on the change of hour (i.e, ‘:00’  min-
               utes) instead of the actual time.

               Set by default to ‘%# ’ in interactive shells.

       prompt2 (+)
               The  string with which to prompt in while and foreach loops and
               after lines ending in ‘\’.  The same format  sequences  may  be
               used  as  in  prompt (q.v.); note the variable meaning of ‘%R’.
               Set by default to ‘%R? ’ in interactive shells.

       prompt3 (+)
               The string with  which  to  prompt  when  confirming  automatic
               spelling  correction.  The same format sequences may be used as
               in prompt (q.v.); note the variable meaning of  ‘%R’.   Set  by
               default to ‘CORRECT>%R (y|n|e|a)? ’ in interactive shells.

       promptchars (+)
               If  set  (to  a  two-character  string),  the  ‘%#’  formatting
               sequence in the prompt shell  variable  is  replaced  with  the
               first  character  for normal users and the second character for
               the superuser.

       pushdtohome (+)
               If set, pushd without arguments does ‘pushd ~’, like cd.

       pushdsilent (+)
               If set, pushd and popd do not print the directory stack.

       recexact (+)
               If set, completion completes on an exact match even if a longer
               match is possible.

       recognize_only_executables (+)
               If  set,  command  listing displays only files in the path that
               are executable.  Slow.

       rmstar (+)
               If set, the user is prompted before ‘rm *’ is executed.

       rprompt (+)
               The string to print on the right-hand side of the screen (after
               the  command  input)  when the prompt is being displayed on the
               left.  It recognizes the same formatting characters as  prompt.
               It  will  automatically disappear and reappear as necessary, to
               ensure that command input isn’t obscured, and will appear  only
               if  the  prompt, command input, and itself will fit together on
               the first line.  If  edit  isn’t  set,  then  rprompt  will  be
               printed after the prompt and before the command input.

       savedirs (+)
               If  set, the shell does ‘dirs -S’ before exiting.  If the first
               word is set to a number, at  most  that  many  directory  stack
               entries are saved.

               If  set,  the  shell  does ‘history -S’ before exiting.  If the
               first word is set to a number, at  most  that  many  lines  are
               saved.  (The number must be less than or equal to history.)  If
               the second word is set to ‘merge’, the history list  is  merged
               with  the  existing  history  file  instead of replacing it (if
               there is one) and sorted by time  stamp  and  the  most  recent
               events are retained.  (+)

       sched (+)
               The  format in which the sched builtin command prints scheduled
               events; if not  given,  ‘%h\t%T\t%R\n’  is  used.   The  format
               sequences  are  described above under prompt; note the variable
               meaning of ‘%R’.

       shell   The file in which the shell resides.  This is used  in  forking
               shells  to  interpret  files  which  have execute bits set, but
               which are not executable by the system.  (See  the  description
               of  Builtin and non-builtin command execution.)  Initialized to
               the (system-dependent) home of the shell.

       shlvl (+)
               The number of nested shells.  Reset to 1 in login shells.   See
               also loginsh.

       status  The  status  returned  by  the  last command.  If it terminated
               abnormally, then 0200 is added to the status.  Builtin commands
               which  fail  return exit status ‘1’, all other builtin commands
               return status ‘0’.

       symlinks (+)
               Can be set to several different values to control symbolic link
               (‘symlink’) resolution:

               If  set to ‘chase’, whenever the current directory changes to a
               directory containing a symbolic link, it  is  expanded  to  the
               real name of the directory to which the link points.  This does
               not work for the user’s home directory; this is a bug.

               If set to ‘ignore’, the shell  tries  to  construct  a  current
               directory relative to the current directory before the link was
               crossed.  This means that cding through  a  symbolic  link  and
               then  ‘cd  ..’ing  returns one to the original directory.  This
               affects only builtin commands and filename completion.

               If set to ‘expand’, the shell tries to fix  symbolic  links  by
               actually  expanding arguments which look like path names.  This
               affects any command, not just  builtins.   Unfortunately,  this
               does  not  work  for hard-to-recognize filenames, such as those
               embedded in command options.  Expansion  may  be  prevented  by
               quoting.  While this setting is usually the most convenient, it
               is sometimes misleading and sometimes confusing when  it  fails
               to  recognize  an argument which should be expanded.  A compro-
               mise is to use ‘ignore’ and use the editor  command  normalize-
               path (bound by default to ^X-n) when necessary.

               Some  examples  are  in  order.   First, let’s set up some play

                   > cd /tmp
                   > mkdir from from/src to
                   > ln -s from/src to/dst

               Here’s the behavior with symlinks unset,

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd

               here’s the behavior with symlinks set to ‘chase’,

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd

               here’s the behavior with symlinks set to ‘ignore’,

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd

               and here’s the behavior with symlinks set to ‘expand’.

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd
                   > cd /tmp/to/dst; echo $cwd
                   > cd ".."; echo $cwd
                   > /bin/echo ..
                   > /bin/echo ".."

               Note that ‘expand’ expansion 1) works just  like  ‘ignore’  for
               builtins  like  cd,  2) is prevented by quoting, and 3) happens
               before filenames are passed to non-builtin commands.

       tcsh (+)
               The version number of the shell in the format ‘R.VV.PP’,  where
               ‘R’  is  the major release number, ‘VV’ the current version and
               ‘PP’ the patchlevel.

       term    The terminal type.  Usually set in ~/.login as described  under
               Startup and shutdown.

       time    If set to a number, then the time builtin (q.v.) executes auto-
               matically after each command which takes more  than  that  many
               CPU seconds.  If there is a second word, it is used as a format
               string for the output of the time builtin.  (u)  The  following
               sequences may be used in the format string:

               %U  The time the process spent in user mode in cpu seconds.
               %S  The time the process spent in kernel mode in cpu seconds.
               %E  The elapsed (wall clock) time in seconds.
               %P  The CPU percentage computed as (%U + %S) / %E.
               %W  Number of times the process was swapped.
               %X  The average amount in (shared) text space used in Kbytes.
               %D  The  average  amount in (unshared) data/stack space used in
               %K  The total space used (%X + %D) in Kbytes.
               %M  The maximum memory the process had in use at  any  time  in
               %F  The  number of major page faults (page needed to be brought
                   from disk).
               %R  The number of minor page faults.
               %I  The number of input operations.
               %O  The number of output operations.
               %r  The number of socket messages received.
               %s  The number of socket messages sent.
               %k  The number of signals received.
               %w  The number of voluntary context switches (waits).
               %c  The number of involuntary context switches.

               Only the first four sequences are supported on systems  without
               BSD  resource limit functions.  The default time format is ‘%Uu
               %Ss %E %P %X+%Dk %I+%Oio %Fpf+%Ww’  for  systems  that  support
               resource  usage  reporting and ‘%Uu %Ss %E %P’ for systems that
               do not.

               Under Sequent’s DYNIX/ptx, %X,  %D,  %K,  %r  and  %s  are  not
               available, but the following additional sequences are:

               %Y  The number of system calls performed.
               %Z  The number of pages which are zero-filled on demand.
               %i  The  number  of  times  a  process’s  resident set size was
                   increased by the kernel.
               %d  The number of times  a  process’s  resident  set  size  was
                   decreased by the kernel.
               %l  The number of read system calls performed.
               %m  The number of write system calls performed.
               %p  The number of reads from raw disk devices.
               %q  The number of writes to raw disk devices.

               and  the  default  time  format  is  ‘%Uu  %Ss  %E  %P  %I+%Oio
               %Fpf+%Ww’.  Note that the CPU percentage  can  be  higher  than
               100% on multi-processors.

       tperiod (+)
               The period, in minutes, between executions of the periodic spe-
               cial alias.

       tty (+) The name of the tty, or empty if not attached to one.

       uid (+) The user’s real user ID.

       user    The user’s login name.

       verbose If set, causes the words of each command to be  printed,  after
               history  substitution  (if  any).   Set  by the -v command line

       version (+)
               The version ID stamp.  It contains the shell’s  version  number
               (see  tcsh), origin, release date, vendor, operating system and
               machine (see VENDOR, OSTYPE and MACHTYPE) and a comma-separated
               list  of options which were set at compile time.  Options which
               are set by default in the distribution are noted.

               8b    The shell is eight bit clean; default
               7b    The shell is not eight bit clean
               wide  The shell is multibyte encoding clean (like UTF-8)
               nls   The system’s NLS is used; default for systems with NLS
               lf    Login shells execute  /etc/csh.login  before  instead  of
                     after /etc/csh.cshrc and ~/.login before instead of after
                     ~/.tcshrc and ~/.history.
               dl    ‘.’ is put last in path for security; default
               nd    ‘.’ is omitted from path for security
               vi    vi-style editing is the default rather than emacs
               dtr   Login shells drop DTR when exiting
               bye   bye is a synonym for logout and log is an alternate  name
                     for watchlog
               al    autologout is enabled; default
               kan   Kanji  is  used  if  appropriate according to locale set-
                     tings, unless the nokanji shell variable is set
               sm    The system’s malloc(3) is used
               hb    The ‘#!<program> <args>’ convention is emulated when exe-
                     cuting shell scripts
               ng    The newgrp builtin is available
               rh    The  shell  attempts  to  set  the REMOTEHOST environment
               afs   The shell verifies your password with the kerberos server
                     if  local  authentication fails.  The afsuser shell vari-
                     able or the AFSUSER environment  variable  override  your
                     local username if set.

               An  administrator may enter additional strings to indicate dif-
               ferences in the local version.

       visiblebell (+)
               If set, a screen flash is used rather than  the  audible  bell.
               See also nobeep.

       watch (+)
               A  list of user/terminal pairs to watch for logins and logouts.
               If either the user is ‘any’ all terminals are watched  for  the
               given  user  and  vice  versa.   Setting  watch  to ‘(any any)’
               watches all users and terminals.  For example,

                   set watch = (george ttyd1 any console $user any)

               reports activity of the user ‘george’ on ttyd1, any user on the
               console, and oneself (or a trespasser) on any terminal.

               Logins and logouts are checked every 10 minutes by default, but
               the first word of watch can be set to a number to  check  every
               so many minutes.  For example,

                   set watch = (1 any any)

               reports any login/logout once every minute.  For the impatient,
               the log builtin command triggers a watch report  at  any  time.
               All  current logins are reported (as with the log builtin) when
               watch is first set.

               The who shell variable controls the format of watch reports.

       who (+) The format string for watch messages.  The following  sequences
               are replaced by the given information:

               %n  The name of the user who logged in/out.
               %a  The  observed  action,  i.e.,  ‘logged on’, ‘logged off’ or
                   ‘replaced olduser on’.
               %l  The terminal (tty) on which the user logged in/out.
               %M  The full hostname of the remote host,  or  ‘local’  if  the
                   login/logout was from the local host.
               %m  The  hostname  of the remote host up to the first ‘.’.  The
                   full name is printed if it is an IP address or an X  Window
                   System display.

               %M  and  %m are available on only systems that store the remote
               hostname in /etc/utmp.  If unset, ‘%n has %a %l  from  %m.’  is
               used,  or  ‘%n  has  %a  %l.’  on systems which don’t store the
               remote hostname.

       wordchars (+)
               A list of non-alphanumeric characters to be considered part  of
               a  word  by  the  forward-word, backward-word etc., editor com-
               mands.  If unset, ‘*?_-.[]~=’ is used.


       AFSUSER (+)
               Equivalent to the afsuser shell variable.

       COLUMNS The number of columns in the terminal.   See  Terminal  manage-

       DISPLAY Used by X Window System (see X(1)).  If set, the shell does not
               set autologout (q.v.).

       EDITOR  The pathname to a default editor.  See also the VISUAL environ-
               ment variable and the run-fg-editor editor command.

       GROUP (+)
               Equivalent to the group shell variable.

       HOME    Equivalent to the home shell variable.

       HOST (+)
               Initialized  to  the  name of the machine on which the shell is
               running, as determined by the gethostname(2) system call.

       HOSTTYPE (+)
               Initialized to the type of machine on which the shell  is  run-
               ning, as determined at compile time.  This variable is obsolete
               and will be removed in a future version.

       HPATH (+)
               A colon-separated list of directories  in  which  the  run-help
               editor command looks for command documentation.

       LANG    Gives the preferred character environment.  See Native Language
               System support.

               If set, only ctype character handling is changed.   See  Native
               Language System support.

       LINES   The  number of lines in the terminal.  See Terminal management.

               The format of this variable is reminiscent  of  the  termcap(5)
               file  format; a colon-separated list of expressions of the form
               "xx=string", where "xx" is a two-character variable name.   The
               variables with their associated defaults are:

                   no   0      Normal (non-filename) text
                   fi   0      Regular file
                   di   01;34  Directory
                   ln   01;36  Symbolic link
                   pi   33     Named pipe (FIFO)
                   so   01;35  Socket
                   do   01;35  Door
                   bd   01;33  Block device
                   cd   01;32  Character device
                   ex   01;32  Executable file
                   mi   (none) Missing file (defaults to fi)
                   or   (none) Orphaned symbolic link (defaults to ln)
                   lc   ^[[    Left code
                   rc   m      Right code
                   ec   (none) End code (replaces lc+no+rc)

               You  need to include only the variables you want to change from
               the default.

               File names can also be colorized based on  filename  extension.
               This  is  specified  in the LS_COLORS variable using the syntax
               "*ext=string".  For example, using ISO 6429 codes, to color all
               C-language  source files blue you would specify "*.c=34".  This
               would color all files ending in .c in blue (34) color.

               Control characters can be  written  either  in  C-style-escaped
               notation,  or  in  stty-like  ^-notation.  The C-style notation
               adds ^[ for Escape, _ for a normal space character, and  ?  for
               Delete.   In  addition,  the ^[ escape character can be used to
               override the default interpretation of ^[, ^, : and =.

               Each file will be written as <lc> <color-code> <rc>  <filename>
               <ec>.   If  the  <ec> code is undefined, the sequence <lc> <no>
               <rc> will be used instead.  This is generally  more  convenient
               to  use,  but  less general.  The left, right and end codes are
               provided so you don’t have to type common parts over  and  over
               again  and  to  support weird terminals; you will generally not
               need to change them at all unless your terminal  does  not  use
               ISO 6429 color sequences but a different system.

               If your terminal does use ISO 6429 color codes, you can compose
               the type codes (i.e., all except the lc, rc, and ec codes) from
               numerical  commands  separated  by semicolons.  The most common
               commands are:

                       0   to restore default color
                       1   for brighter colors
                       4   for underlined text
                       5   for flashing text
                       30  for black foreground
                       31  for red foreground
                       32  for green foreground
                       33  for yellow (or brown) foreground
                       34  for blue foreground
                       35  for purple foreground
                       36  for cyan foreground
                       37  for white (or gray) foreground
                       40  for black background
                       41  for red background
                       42  for green background
                       43  for yellow (or brown) background
                       44  for blue background
                       45  for purple background
                       46  for cyan background
                       47  for white (or gray) background

               Not all commands will work on all systems or display devices.

               A few terminal programs do not recognize the default  end  code
               properly.   If all text gets colorized after you do a directory
               listing, try changing the no and fi codes from 0 to the numeri-
               cal codes for your standard fore- and background colors.

       MACHTYPE (+)
               The  machine  type  (microprocessor class or machine model), as
               determined at compile time.

       NOREBIND (+)
               If set, printable characters are not  rebound  to  self-insert-
               command.  See Native Language System support.

       OSTYPE (+)
               The operating system, as determined at compile time.

       PATH    A colon-separated list of directories in which to look for exe-
               cutables.  Equivalent to the path shell variable, but in a dif-
               ferent format.

       PWD (+) Equivalent  to  the cwd shell variable, but not synchronized to
               it; updated only after an actual directory change.

       REMOTEHOST (+)
               The host from which the user has logged in remotely, if this is
               the  case  and  the shell is able to determine it.  Set only if
               the shell was so compiled; see the version shell variable.

       SHLVL (+)
               Equivalent to the shlvl shell variable.

       SYSTYPE (+)
               The current system type.  (Domain/OS only)

       TERM    Equivalent to the term shell variable.

       TERMCAP The terminal capability string.  See Terminal management.

       USER    Equivalent to the user shell variable.

       VENDOR (+)
               The vendor, as determined at compile time.

       VISUAL  The pathname to a default full-screen  editor.   See  also  the
               EDITOR  environment  variable and the run-fg-editor editor com-


       /etc/csh.cshrc  Read first by every shell.  ConvexOS, Stellix and Intel
                       use  /etc/cshrc  and  NeXTs  use /etc/cshrc.std.  A/UX,
                       AMIX, Cray and IRIX have no equivalent in  csh(1),  but
                       read  this  file  in tcsh anyway.  Solaris 2.x does not
                       have it either, but tcsh reads /etc/.cshrc.  (+)
       /etc/csh.login  Read by login shells after  /etc/csh.cshrc.   ConvexOS,
                       Stellix   and   Intel   use   /etc/login,   NeXTs   use
                       /etc/login.std, Solaris 2.x uses /etc/.login and  A/UX,
                       AMIX, Cray and IRIX use /etc/cshrc.
       ~/.tcshrc (+)   Read by every shell after /etc/csh.cshrc or its equiva-
       ~/.cshrc        Read by every shell, if ~/.tcshrc doesn’t exist,  after
                       /etc/csh.cshrc  or  its  equivalent.   This manual uses
                       ‘~/.tcshrc’ to mean ‘~/.tcshrc or, if ~/.tcshrc is  not
                       found, ~/.cshrc’.
       ~/.history      Read  by  login  shells  after ~/.tcshrc if savehist is
                       set, but see also histfile.
       ~/.login        Read by login shells  after  ~/.tcshrc  or  ~/.history.
                       The  shell  may  be  compiled  to  read ~/.login before
                       instead of after ~/.tcshrc and ~/.history; see the ver-
                       sion shell variable.
       ~/.cshdirs (+)  Read by login shells after ~/.login if savedirs is set,
                       but see also dirsfile.
       /etc/csh.logout Read by login shells at logout.  ConvexOS, Stellix  and
                       Intel  use  /etc/logout  and NeXTs use /etc/logout.std.
                       A/UX, AMIX, Cray and IRIX have no equivalent in csh(1),
                       but  read  this  file in tcsh anyway.  Solaris 2.x does
                       not have it either, but tcsh reads /etc/.logout.  (+)
       ~/.logout       Read by login shells at logout after /etc/csh.logout or
                       its equivalent.
       /bin/sh         Used  to  interpret  shell  scripts not starting with a
       /tmp/sh*        Temporary file for ‘<<’.
       /etc/passwd     Source of home directories for ‘~name’ substitutions.

       The order in which startup files are read may differ if the  shell  was
       so compiled; see Startup and shutdown and the version shell variable.


       This  manual  describes tcsh as a single entity, but experienced csh(1)
       users will want to pay special attention to tcsh’s new features.

       A command-line editor, which supports  GNU  Emacs  or  vi(1)-style  key
       bindings.  See The command-line editor and Editor commands.

       Programmable,  interactive word completion and listing.  See Completion
       and listing and the complete and uncomplete builtin commands.

       Spelling correction (q.v.) of filenames, commands and variables.

       Editor commands (q.v.) which perform other useful functions in the mid-
       dle of typed commands, including documentation lookup (run-help), quick
       editor restarting (run-fg-editor) and  command  resolution  (which-com-

       An  enhanced  history  mechanism.  Events in the history list are time-
       stamped.  See also the history command and its associated  shell  vari-
       ables,  the  previously  undocumented ‘#’ event specifier and new modi-
       fiers under History substitution, the *-history,  history-search-*,  i-
       search-*,  vi-search-*  and  toggle-literal-history editor commands and
       the histlit shell variable.

       Enhanced directory parsing and directory stack handling.  See  the  cd,
       pushd, popd and dirs commands and their associated shell variables, the
       description of Directory stack substitution, the dirstack, owd and sym-
       links shell variables and the normalize-command and normalize-path edi-
       tor commands.

       Negation in glob-patterns.  See Filename substitution.

       New File inquiry operators (q.v.) and a  filetest  builtin  which  uses

       A  variety  of  Automatic,  periodic  and timed events (q.v.) including
       scheduled events, special aliases, automatic logout and terminal  lock-
       ing, command timing and watching for logins and logouts.

       Support for the Native Language System (see Native Language System sup-
       port), OS variant features (see OS variant support and  the  echo_style
       shell variable) and system-dependent file locations (see FILES).

       Extensive terminal-management capabilities.  See Terminal management.

       New  builtin  commands including builtins, hup, ls-F, newgrp, printenv,
       which and where (q.v.).

       New variables that make useful  information  easily  available  to  the
       shell.   See  the  gid, loginsh, oid, shlvl, tcsh, tty, uid and version
       shell variables and the HOST, REMOTEHOST, VENDOR, OSTYPE  and  MACHTYPE
       environment variables.

       A new syntax for including useful information in the prompt string (see
       prompt).  and special prompts for loops and  spelling  correction  (see
       prompt2 and prompt3).

       Read-only variables.  See Variable substitution.


       When  a  suspended command is restarted, the shell prints the directory
       it started in if this is different from the  current  directory.   This
       can be misleading (i.e., wrong) as the job may have changed directories

       Shell  builtin  functions  are  not   stoppable/restartable.    Command
       sequences  of the form ‘a ; b ; c’ are also not handled gracefully when
       stopping is attempted.  If you suspend ‘b’, the shell will then immedi-
       ately  execute  ‘c’.   This  is especially noticeable if this expansion
       results from an alias.  It suffices to place the sequence  of  commands
       in ()’s to force it to a subshell, i.e., ‘( a ; b ; c )’.

       Control  over tty output after processes are started is primitive; per-
       haps this will inspire someone to  work  on  a  good  virtual  terminal
       interface.   In  a  virtual  terminal  interface  much more interesting
       things could be done with output control.

       Alias substitution is most often used to clumsily simulate shell proce-
       dures; shell procedures should be provided rather than aliases.

       Commands  within  loops  are  not  placed in the history list.  Control
       structures should be parsed rather than being  recognized  as  built-in
       commands.   This would allow control commands to be placed anywhere, to
       be combined with ‘|’, and to be used with ‘&’ and ‘;’ metasyntax.

       foreach doesn’t ignore here documents when looking for its end.

       It should be possible to use the ‘:’ modifiers on the output of command

       The  screen  update for lines longer than the screen width is very poor
       if the terminal cannot move the cursor up (i.e., terminal type ‘dumb’).

       HPATH and NOREBIND don’t need to be environment variables.

       Glob-patterns  which  do  not use ‘?’, ‘*’ or ‘[]’ or which use ‘{}’ or
       ‘~’ are not negated correctly.

       The single-command form of if  does  output  redirection  even  if  the
       expression is false and the command is not executed.

       ls-F includes file identification characters when sorting filenames and
       does not handle control characters in filenames  well.   It  cannot  be

       Command substitution supports multiple commands and conditions, but not
       cycles or backward gotos.

       Report bugs at http://bugs.gw.com/, preferably with fixes.  If you want
       to  help  maintain  and  test tcsh, send mail to tcsh-request@mx.gw.com
       with the text ‘subscribe tcsh’ on a line by itself in the body.


       In 1964, DEC produced the PDP-6.  The PDP-10 was a later re-implementa-
       tion.   It  was  re-christened  the DECsystem-10 in 1970 or so when DEC
       brought out the second model, the KI10.

       TENEX was created at Bolt, Beranek & Newman (a Cambridge, Massachusetts
       think  tank)  in  1972  as an experiment in demand-paged virtual memory
       operating systems.  They built a new pager for the DEC PDP-10 and  cre-
       ated the OS to go with it.  It was extremely successful in academia.

       In  1975,  DEC  brought  out  a new model of the PDP-10, the KL10; they
       intended to have only a version of TENEX, which they had licensed  from
       BBN,  for  the new box.  They called their version TOPS-20 (their capi-
       talization is trademarked).  A lot of  TOPS-10  users  (‘The  OPerating
       System  for PDP-10’) objected; thus DEC found themselves supporting two
       incompatible systems on the same hardware--but then there were 6 on the

       TENEX,  and  TOPS-20  to  version 3, had command completion via a user-
       code-level subroutine library called ULTCMD.  With version 3, DEC moved
       all  that  capability  and more into the monitor (‘kernel’ for you Unix
       types), accessed by the COMND% JSYS (‘Jump to SYStem’ instruction,  the
       supervisor call mechanism [are my IBM roots also showing?]).

       The creator of tcsh was impressed by this feature and several others of
       TENEX and TOPS-20, and created a version of csh which mimicked them.


       Words can be no longer than 1024 characters.

       The system limits argument lists to 10240 characters.

       The number of arguments to a command which involves filename  expansion
       is  limited  to  1/6th  the number of characters allowed in an argument

       Command substitutions  may  substitute  no  more  characters  than  are
       allowed in an argument list.

       To  detect  looping,  the shell restricts the number of alias substitu-
       tions on a single line to 20.


       csh(1), emacs(1), ls(1), newgrp(1), sh(1), setpath(1), stty(1),  su(1),
       tset(1),   vi(1),   x(1),  access(2),  execve(2),  fork(2),  killpg(2),
       pipe(2), setrlimit(2), sigvec(2), stat(2), umask(2), vfork(2), wait(2),
       malloc(3),  setlocale(3),  tty(4),  a.out(5),  termcap(5),  environ(7),
       termio(7), Introduction to the C Shell


       This manual documents tcsh 6.14.00 (Astron) 2005-03-25.


       William Joy
         Original author of csh(1)
       J.E. Kulp, IIASA, Laxenburg, Austria
         Job control and directory stack features
       Ken Greer, HP Labs, 1981
         File name completion
       Mike Ellis, Fairchild, 1983
         Command name recognition/completion
       Paul Placeway, Ohio State CIS Dept., 1983-1993
         Command line editor, prompt routines, new glob  syntax  and  numerous
         fixes and speedups
       Karl Kleinpaste, CCI 1983-4
         Special  aliases,  directory  stack  extraction  stuff,  login/logout
         watch, scheduled events, and the idea of the new prompt format
       Rayan Zachariassen, University of Toronto, 1984
         ls-F and which builtins and numerous  bug  fixes,  modifications  and
       Chris Kingsley, Caltech
         Fast storage allocator routines
       Chris Grevstad, TRW, 1987
         Incorporated 4.3BSD csh into tcsh
       Christos S. Zoulas, Cornell U. EE Dept., 1987-94
         Ports   to   HPUX,   SVR2  and  SVR3,  a  SysV  version  of  getwd.c,
         SHORT_STRINGS support and a new version of sh.glob.c
       James J Dempsey, BBN, and Paul Placeway, OSU, 1988
         A/UX port
       Daniel Long, NNSC, 1988
       Patrick Wolfe, Kuck and Associates, Inc., 1988
         vi mode cleanup
       David C Lawrence, Rensselaer Polytechnic Institute, 1989
         autolist and ambiguous completion listing
       Alec Wolman, DEC, 1989
         Newlines in the prompt
       Matt Landau, BBN, 1989
       Ray Moody, Purdue Physics, 1989
         Magic space bar history expansion
       Mordechai ????, Intel, 1989
         printprompt() fixes and additions
       Kazuhiro Honda, Dept. of Computer Science, Keio University, 1989
         Automatic spelling correction and prompt3
       Per Hedeland, Ellemtel, Sweden, 1990-
         Various bugfixes, improvements and manual updates
       Hans J. Albertsson (Sun Sweden)
         ampm, settc and telltc
       Michael Bloom
         Interrupt handling fixes
       Michael Fine, Digital Equipment Corp
         Extended key support
       Eric Schnoebelen, Convex, 1990
         Convex support, lots of csh bug fixes, save and restore of  directory
       Ron Flax, Apple, 1990
         A/UX 2.0 (re)port
       Dan Oscarsson, LTH Sweden, 1990
         NLS support and simulated NLS support for non NLS sites, fixes
       Johan Widen, SICS Sweden, 1990
         shlvl, Mach support, correct-line, 8-bit printing
       Matt Day, Sanyo Icon, 1990
         POSIX termio support, SysV limit fixes
       Jaap Vermeulen, Sequent, 1990-91
         Vi mode fixes, expand-line, window change fixes, Symmetry port
       Martin Boyer, Institut de recherche d’Hydro-Quebec, 1991
         autolist  beeping  options, modified the history search to search for
         the whole string from the beginning of the line to the cursor.
       Scott Krotz, Motorola, 1991
         Minix port
       David Dawes, Sydney U. Australia, Physics Dept., 1991
         SVR4 job control fixes
       Jose Sousa, Interactive Systems Corp., 1991
         Extended vi fixes and vi delete command
       Marc Horowitz, MIT, 1991
         ANSIfication fixes, new exec hashing code, imake fixes, where
       Bruce Sterling Woodcock, sterling@netcom.com, 1991-1995
         ETA and Pyramid port, Makefile and lint fixes, ignoreeof=n  addition,
         and various other portability changes and bug fixes
       Jeff Fink, 1992
         complete-word-fwd and complete-word-back
       Harry C. Pulley, 1992
         Coherent port
       Andy Phillips, Mullard Space Science Lab U.K., 1992
         VMS-POSIX port
       Beto Appleton, IBM Corp., 1992
         Walking  process  group fixes, csh bug fixes, POSIX file tests, POSIX
       Scott Bolte, Cray Computer Corp., 1992
         CSOS port
       Kaveh R. Ghazi, Rutgers University, 1992
         Tek, m88k, Titan and Masscomp ports and fixes.  Added  autoconf  sup-
       Mark Linderman, Cornell University, 1992
         OS/2 port
       Mika Liljeberg, liljeber@kruuna.Helsinki.FI, 1992
         Linux port
       Tim P. Starrin, NASA Langley Research Center Operations, 1993
         Read-only variables
       Dave Schweisguth, Yale University, 1993-4
         New man page and tcsh.man2html
       Larry Schwimmer, Stanford University, 1993
         AFS and HESIOD patches
       Luke Mewburn, RMIT University, 1994-6
         Enhanced directory printing in prompt, added ellipsis and rprompt.
       Edward Hutchins, Silicon Graphics Inc., 1996
         Added implicit cd.
       Martin Kraemer, 1997
         Ported to Siemens Nixdorf EBCDIC machine
       Amol Deshpande, Microsoft, 1997
         Ported  to  WIN32  (Windows/95 and Windows/NT); wrote all the missing
         library and message catalog code to interface to Windows.
       Taga Nayuta, 1998
         Color ls additions.


       Bryan Dunlap, Clayton Elwell, Karl Kleinpaste, Bob Manson, Steve Romig,
       Diana  Smetters, Bob Sutterfield, Mark Verber, Elizabeth Zwicky and all
       the other people at Ohio State for suggestions and encouragement

       All the people on the net, for putting up with, reporting bugs in,  and
       suggesting new additions to each and every version

       Richard M. Alderson III, for writing the ‘T in tcsh’ section

Astron 6.14.00                   25 March 2005                         TCSH(1)

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