ctags



CTAGS(1)                        Exuberant Ctags                       CTAGS(1)




NAME

       ctags - Generate tag files for source code




SYNOPSIS

       ctags [options] [file(s)]

       etags [options] [file(s)]




DESCRIPTION

       The  ctags  and etags programs (hereinafter collectively referred to as
       ctags, except where distinguished) generate an index  (or  "tag")  file
       for  a  variety  of  language  objects found in file(s).  This tag file
       allows these items to be quickly and easily located by a text editor or
       other  utility.  A "tag" signifies a language object for which an index
       entry is available (or, alternatively, the index entry created for that
       object).

       Alternatively,  ctags  can generate a cross reference file which lists,
       in human readable form, information about the  various  source  objects
       found in a set of language files.

       Tag index files are supported by numerous editors, which allow the user
       to locate the object associated with a name appearing in a source  file
       and jump to the file and line which defines the name. Those known about
       at the time of this release are:

           Vi(1) and its derivatives (e.g. Elvis, Vim,  Vile,  Lemmy),  CRiSP,
           Emacs, FTE (Folding Text Editor), JED, jEdit, Mined, NEdit (Nirvana
           Edit), TSE (The SemWare Editor), UltraEdit, WorkSpace, X2, Zeus

       Ctags is capable of generating different kinds of tags for each of many
       different  languages.  For  a complete list of supported languages, the
       names by which they are recognized, and the kinds  of  tags  which  are
       generated  for each, see the --list-languages and --list-kinds options.




SOURCE FILES

       Unless the --language-force option is specified, the language  of  each
       source  file  is  automatically  selected  based upon a mapping of file
       names to languages. The mappings in effect for  each  language  may  be
       display  using  the  --list-maps  option  and  may be changed using the
       --langmap option.  On platforms which support it, if the name of a file
       is  not mapped to a language and the file is executable, the first line
       of the file is checked to see if the file is a "#!" script for a recog-
       nized language.

       By  default,  all  other  files names are ignored. This permits running
       ctags on all files in either a single directory (e.g. "ctags *"), or on
       all  files  in an entire source directory tree (e.g. "ctags -R"), since
       only those files whose names are mapped to languages will be scanned.

       [The reason that .h extensions are mapped to C++ files  rather  than  C
       files  is because it is common to use .h extensions in C++, and no harm
       results in treating them as C++ files.]




OPTIONS

       Despite the wealth of available options, defaults are set so that ctags
       is  most  commonly  executed  without  any  options (e.g. "ctags *", or
       "ctags -R"), which will create a tag file in the current directory  for
       all  recognized  source files. The options described below are provided
       merely to allow custom tailoring to meet special needs.

       Note that spaces separating the single-letter options from their param-
       eters are optional.

       Note  also  that the boolean parameters to the long form options (those
       beginning with "--" and that take a "[=yes|no]" parameter) may be omit-
       ted,  in  which  case  "=yes" is implied. (e.g. --sort is equivalent to
       --sort=yes). Note further that "=1" and "=on" are  considered  synonyms
       for "=yes", and that "=0" and "=off" are considered synonyms for "=no".

       Some options are either ignored or useful only when used while  running
       in etags mode (see -e option). Such options will be noted.

       Most  options  may  appear anywhere on the command line, affecting only
       those files which follow the  option.  A  few  options,  however,  must
       appear before the first file name and will be noted as such.

       Options  taking  language names will accept those names in either upper
       or lower case. See the --list-languages option for a complete  list  of
       the built-in language names.


       -a   Equivalent to --append.


       -B   Use  backward  searching  patterns  (e.g.  ?pattern?). [Ignored in
            etags mode]


       -e   Enable etags mode, which will create a tag file for use  with  the
            Emacs  editor.   Alternatively, if ctags is invoked by a name con-
            taining the string "etags" (either by renaming, or creating a link
            to,  the executable), etags mode will be enabled. This option must
            appear before the first file name.


       -f tagfile
            Use the name specified by tagfile for the  tag  file  (default  is
            "tags", or "TAGS" when running in etags mode). If tagfile is spec-
            ified as "-", then the tag file  is  written  to  standard  output
            instead.  Ctags  will  stubbornly refuse to take orders if tagfile
            exists and its first line contains something other  than  a  valid
            tags  line. This will save your neck if you mistakenly type "ctags
            -f *.c", which would otherwise overwrite your first  C  file  with
            the  tags  generated  by the rest! It will also refuse to accept a
            multi character file name which begins with a ’-’  (dash)  charac-
            ter,  since  this most likely means that you left out the tag file
            name and this option tried to grab the next  option  as  the  file
            name.  If  you  really  want to name your output tag file "-ugly",
            specify it as "./-ugly". This option must appear before the  first
            file  name.  If  this option is specified more than once, only the
            last will apply.


       -F   Use  forward  searching  patterns  (e.g.   /pattern/)   (default).
            [Ignored in etags mode]


       -h list
            Specifies  a  list of file extensions, separated by periods, which
            are to be interpreted as include (or header)  files.  To  indicate
            files  having  no  extension,  use a period not followed by a non-
            period character  (e.g.  ".",  "..x",  ".x.").  This  option  only
            affects  how  the  scoping of a particular kinds of tags is inter-
            preted (i.e. whether or not they are considered as globally  visi-
            ble or visible only within the file in which they are defined); it
            does not map the extension to any  particular  language.  Any  tag
            which  is  located  in a non-include file and cannot be seen (e.g.
            linked to) from another file is considered  to  have  file-limited
            (e.g.  static)  scope. No kind of tag appearing in an include file
            will be considered to have file-limited scope. If the first  char-
            acter  in the list is a plus sign, then the extensions in the list
            will be appended to the current list;  otherwise,  the  list  will
            replace  the current list. See, also, the --file-scope option. The
            default list  is  ".h.H.hh.hpp.hxx.h++.inc.def".  To  restore  the
            default  list,  specify -h default. Note that if an extension sup-
            plied to this option is not already mapped to  a  particular  lan-
            guage  (see SOURCE FILES, above), you will also need to use either
            the --langmap or --language-force option.


       -I identifier-list
            Specifies a list of identifiers which are to be specially  handled
            while  parsing C and C++ source files. This option is specifically
            provided to handle special cases arising through the use  of  pre-
            processor  macros.  When the identifiers listed are simple identi-
            fiers, these identifiers will be ignored  during  parsing  of  the
            source  files.  If an identifier is suffixed with a ’+’ character,
            ctags will also  ignore  any  parenthesis-enclosed  argument  list
            which  may  immediately follow the identifier in the source files.
            If two identifiers are separated with the ’=’ character, the first
            identifiers is replaced by the second identifiers for parsing pur-
            poses. The list of identifiers may be  supplied  directly  on  the
            command line or read in from a separate file. If the first charac-
            ter of identifier-list is ’@’, ’.’ or a pathname separator (’/’ or
            ’\’),  or  the  first  two characters specify a drive letter (e.g.
            "C:"), the parameter identifier-list  will  be  interpreted  as  a
            filename  from  which to read a list of identifiers, one per input
            line. Otherwise, identifier-list is  a  list  of  identifiers  (or
            identifier  pairs)  to  be  specially handled, each delimited by a
            either a comma or by white space (in which case the list should be
            quoted to keep the entire list as one command line argument). Mul-
            tiple -I options may be supplied.  To clear  the  list  of  ignore
            identifiers, supply a single dash ("-") for identifier-list.

            This feature is useful when preprocessor macros are used in such a
            way that they cause syntactic confusion  due  to  their  presence.
            Indeed,  this  is the best way of working around a number of prob-
            lems caused by the presence of  syntax-busting  macros  in  source
            files  (see  CAVEATS,  below).  Some examples will illustrate this
            point.

               int foo ARGDECL4(void *, ptr, long int, nbytes)


            In the above example, the macro  "ARGDECL4"  would  be  mistakenly
            interpreted  to be the name of the function instead of the correct
            name of "foo". Specifying  -I  ARGDECL4  results  in  the  correct
            behavior.

               /* creates an RCS version string in module */
               MODULE_VERSION("$Revision: 1.38 $")


            In  the  above  example the macro invocation looks too much like a
            function definition because it is  not  followed  by  a  semicolon
            (indeed, it could even be followed by a global variable definition
            that  would  look  much  like  a  K&R  style  function   parameter
            declaration). In fact, this seeming function definition could pos-
            sibly even cause the rest of the file to  be  skipped  over  while
            trying  to  complete the definition. Specifying -I MODULE_VERSION+
            would avoid such a problem.

               CLASS Example {
                   // your content here
               };


            The example above uses  "CLASS"  as  a  preprocessor  macro  which
            expands  to  something  different  for each platform. For instance
            CLASS may be defined as  "class  __declspec(dllexport)"  on  Win32
            platforms  and  simply  "class" on UNIX.  Normally, the absence of
            the C++ keyword "class" would cause the source file to  be  incor-
            rectly  parsed.  Correct behavior can be restored by specifying -I
            CLASS=class.


       -L file
            Read from file a list of file names for which tags should be  gen-
            erated.   If  file  is  specified as "-", then file names are read
            from standard input. File names read using this  option  are  pro-
            cessed following file names appearing on the command line. Options
            all also accepted in this input. If this option is specified  more
            than  once,  only the last will apply. Note: file is read in line-
            oriented mode, where a new line is the only delimiter  and  spaces
            are  considered  significant,  in order that file names containing
            spaces may be supplied; this can affect how options are parsed  if
            included in the input.


       -n   Equivalent to --excmd=number.


       -N   Equivalent to --excmd=pattern.


       -o tagfile
            Equivalent to -f tagfile.


       -R   Equivalent to --recurse.


       -u   Equivalent to --sort=no (i.e. "unsorted").


       -V   Equivalent to --verbose.


       -w   This  option  is  silently ignored for backward-compatibility with
            the ctags of SVR4 Unix.


       -x   Print a tabular, human-readable cross  reference  (xref)  file  to
            standard  output instead of generating a tag file. The information
            contained in the output includes: the tag name; the kind  of  tag;
            the  line  number,  file  name,  and source line (with extra white
            space condensed) of the file which defines the tag. No tag file is
            written and all options affecting tag file output will be ignored.
            Example applications for this feature are generating a listing  of
            all  functions located in a source file (e.g. ctags -x --c-kinds=f
            file), or generating a list of all externally visible global vari-
            ables  located in a source file (e.g. ctags -x --c-kinds=v --file-
            scope=no file). This option must  appear  before  the  first  file
            name.


       --append[=yes|no]
            Indicates  whether  tags generated from the specified files should
            be appended to those already present in the  tag  file  or  should
            replace  them.  This  option  is  off by default. This option must
            appear before the first file name.


       --etags-include=file
            Include a reference to file in the tag file. This  option  may  be
            specified  as many times as desired. This supports Emacs’ capabil-
            ity to use a tag file which "includes" other tag files. [Available
            only in etags mode]


       --exclude=[pattern]
            Add  pattern  to  a  list  of excluded files and directories. This
            option may be specified as many times as desired.  For  each  file
            name considered by ctags, each pattern specified using this option
            will  be  compared  against   both   the   complete   path   (e.g.
            some/path/base.ext) and the base name (e.g. base.ext) of the file,
            thus allowing patterns which match a given file name  irrespective
            of its path, or match only a specific path. If appropriate support
            is available from the runtime library of  your  C  compiler,  then
            pattern may contain the usual shell wildcards (not regular expres-
            sions) common on Unix (be sure to quote the  option  parameter  to
            protect  the  wildcards  from  being  expanded by the shell before
            being passed to ctags; also be aware that wildcards can match  the
            slash  character,  ’/’).  You can determine if shell wildcards are
            available on your platform by examining the output of  the  --ver-
            sion  option, which will include "+wildcards" in the compiled fea-
            ture list; otherwise, pattern is matched against file names  using
            a simple textual comparison.

            If  pattern  begins  with  the character ’@’, then the rest of the
            string is interpreted as a file name from which to read  exclusion
            patterns,  one per line. If pattern is empty, the list of excluded
            patterns is cleared.  Note that at program  startup,  the  default
            exclude  list  contains  "EIFGEN", "SCCS", "RCS", and "CVS", which
            are names of directories for which it is generally  not  desirable
            to descend while processing the --recurse option.


       --excmd=type
            Determines  the  type  of  EX  command  used to locate tags in the
            source file.  [Ignored in etags mode]

            The valid values for type (either the entire  word  or  the  first
            letter is accepted) are:


            number   Use  only line numbers in the tag file for locating tags.
                     This has four advantages:
                     1.  Significantly reduces the size of the  resulting  tag
                         file.
                     2.  Eliminates  failures  to  find  tags because the line
                         defining the tag has  changed,  causing  the  pattern
                         match  to  fail (note that some editors, such as vim,
                         are able to recover in many such instances).
                     3.  Eliminates finding identical matching, but incorrect,
                         source lines (see BUGS, below).
                     4.  Retains  separate  entries  in the tag file for lines
                         which are identical  in  content.  In  pattern  mode,
                         duplicate entries are dropped because the search pat-
                         terns they generate are identical, making the  dupli-
                         cate entries useless.


                     However,   this  option  has  one  significant  drawback:
                     changes to the source files can cause  the  line  numbers
                     recorded  in  the tag file to no longer correspond to the
                     lines in the source file, causing jumps to some  tags  to
                     miss  the  target  definition by one or more lines. Basi-
                     cally, this option is best used when the source  code  to
                     which  it  is applied is not subject to change. Selecting
                     this option type  causes  the  following  options  to  be
                     ignored: -BF.


            pattern  Use  only  search  patterns for all tags, rather than the
                     line numbers usually used for macro definitions. This has
                     the  advantage  of  not referencing obsolete line numbers
                     when lines have been added or removed since the tag  file
                     was generated.


            mixed    In  this  mode,  patterns  are  generally used with a few
                     exceptions. For C, line numbers are used for macro  defi-
                     nition tags. This was the default format generated by the
                     original ctags and is, therefore, retained as the default
                     for  this  option. For Fortran, line numbers are used for
                     common blocks because their  corresponding  source  lines
                     are  generally identical, making pattern searches useless
                     for finding all matches.


       --extra=[+|-]flags
            Specifies whether to include extra tag entries for  certain  kinds
            of  information. The parameter flags is a set of one-letter flags,
            each representing one kind of extra tag entry to  include  in  the
            tag file. If flags is preceded by by either the ’+’ or ’-’ charac-
            ter, the effect of each flag is added to, or removed  from,  those
            currently  enabled;  otherwise  the flags replace any current set-
            tings. The meaning of each flag is as follows:



               f   Include an entry for the base file  name  of  every  source
                   file (e.g.  "example.c"), which addresses the first line of
                   the file.

               q   Include an extra class-qualified tag  entry  for  each  tag
                   which  is a member of a class (for languages for which this
                   information is extracted; currently C++, Eiffel, and Java).
                   The  actual form of the qualified tag depends upon the lan-
                   guage from which the tag was derived (using a form that  is
                   most  natural  for how qualified calls are specified in the
                   language). For C++, it is in the form "class::member";  for
                   Eiffel and Java, it is in the form "class.member". This may
                   allow easier location of  a  specific  tags  when  multiple
                   occurrences of a tag name occur in the tag file. Note, how-
                   ever, that this could potentially more than double the size
                   of the tag file.


       --fields=[+|-]flags
            Specifies  the available extension fields which are to be included
            in the entries of the tag file (see TAG FILE  FORMAT,  below,  for
            more  information).  The  parameter  flags  is a set of one-letter
            flags, each representing one type of extension field  to  include,
            with  the  following  meanings  (disabled  by default unless indi-
            cated):


               a   Access (or export) of class members
               f   File-restricted scoping [enabled]
               i   Inheritance information
               k   Kind of tag as a single letter [enabled]
               K   Kind of tag as full name
               l   Language of source file containing tag
               m   Implementation information
               n   Line number of tag definition
               s   Scope of tag definition [enabled]
               S   Signature of routine (e.g. prototype or parameter list)
               z   Include the "kind:" key in kind field

            Each letter or group of letters may be preceded by either  ’+’  to
            add it to the default set, or ’-’ to exclude it. In the absence of
            any preceding ’+’ or ’-’ sign, only those kinds explicitly  listed
            in  flags  will  be  included  in  the output (i.e. overriding the
            default set). This option is ignored if the option --format=1  has
            been specified. The default value of this options is fks.


       --file-scope[=yes|no]
            Indicates  whether  tags  scoped only for a single file (i.e. tags
            which cannot be seen  outside  of  the  file  in  which  they  are
            defined,  such as "static" tags) should be included in the output.
            See, also, the -h option. This option is enabled by default.


       --filter[=yes|no]
            Causes ctags to behave as a filter, reading source file names from
            standard  input  and  printing  their tags to standard output on a
            file-by-file basis. If --sorted is enabled, tags are  sorted  only
            within  the  source file in which they are defined. File names are
            read from standard output in line-oriented input  mode  (see  note
            for  -L  option)  and  only after file names listed on the command
            line or from any file supplied using  the  -L  option.  When  this
            option  is  enabled, the options -f, -o, and --totals are ignored.
            This option is quite esoteric and is  disabled  by  default.  This
            option must appear before the first file name.


       --filter-terminator=string
            Specifies  a string to print to standard output following the tags
            for each file name parsed when the  --filter  option  is  enabled.
            This  may  permit  an  application  reading the output of ctags to
            determine when the output for each file is finished. Note that  if
            the  file  name read is a directory and --recurse is enabled, this
            string will be printed only one once at the end of all tags  found
            for  by descending the directory. This string will always be sepa-
            rated from the last tag line for the file by its terminating  new-
            line.  This option is quite esoteric and is empty by default. This
            option must appear before the first file name.


       --format=level
            Change the format of the output tag file. Currently the only valid
            values  for  level  are 1 or 2. Level 1 specifies the original tag
            file format and level 2 specifies a new extended format containing
            extension  fields (but in a manner which retains backward-compati-
            bility with original vi(1) implementations). The default level  is
            2. This option must appear before the first file name. [Ignored in
            etags mode]


       --help
            Prints to standard output a detailed usage description,  and  then
            exits.


       --if0[=yes|no]
            Indicates a preference as to whether code within an "#if 0" branch
            of a preprocessor conditional should  be  examined  for  non-macro
            tags  (macro tags are always included). Because the intent of this
            construct is to disable code, the default value of this options is
            no.  Note that this indicates a preference only and does not guar-
            antee skipping code within an "#if 0" branch, since the  fall-back
            algorithm used to generate tags when preprocessor conditionals are
            too complex follows all branches of a conditional. This option  is
            disabled by default.


       --<LANG>-kinds=[+|-]kinds
            Specifies  a list of language-specific kinds of tags (or kinds) to
            include in the output file for a particular language, where <LANG>
            is case-insensitive and is one of the built-in language names (see
            the --list-languages option for a complete  list).  The  parameter
            kinds  is  a  group  of one-letter flags designating kinds of tags
            (particular to the language) to either include or exclude from the
            output.  The  specific sets of flags recognized for each language,
            their meanings and defaults may be  list  using  the  --list-kinds
            option.  Each letter or group of letters may be preceded by either
            ’+’ to add it to, or ’-’ to remove it from, the  default  set.  In
            the  absence  of  any  preceding ’+’ or ’-’ sign, only those kinds
            explicitly listed in kinds will be included in  the  output  (i.e.
            overriding the default for the specified language).

            As  an  example for the C language, in order to add prototypes and
            external variable declarations to the default set  of  tag  kinds,
            but  exclude macros, use --c-kinds=+px-d; to include only tags for
            functions, use --c-kinds=f.


       --langdef=name
            Defines a new user-defined language, name, to be parsed with regu-
            lar  expressions.  Once defined, name may be used in other options
            taking language names. The typical use of this option is to  first
            define  the  language,  then map file names to it using --langmap,
            then specify regular expressions using  --regex-<LANG>  to  define
            how its tags are found.


       --langmap=map[,map[...]]
            Controls  how  file names are mapped to languages (see the --list-
            maps option). Each comma-separated map consists  of  the  language
            name  (either a built-in or user-defined language), a colon, and a
            list of file extensions and/or file name patterns. A  file  exten-
            sion  is  specified by preceding the extension with a period (e.g.
            ".c"). A file name pattern is specified by enclosing  the  pattern
            in  parentheses  (e.g. "([Mm]akefile)"). If appropriate support is
            available from the runtime library of your C  compiler,  then  the
            file  name pattern may contain the usual shell wildcards common on
            Unix (be sure to quote the option parameter to protect  the  wild-
            cards  from  being  expanded  by  the shell before being passed to
            ctags). You can determine if shell wildcards are available on your
            platform  by  examining  the output of the --version option, which
            will include "+wildcards" in the compiled feature list; otherwise,
            the file name patterns are matched against file names using a sim-
            ple textual comparison.

            If the first character in a map is a plus sign,  then  the  exten-
            sions  and  file name patterns in that map will be appended to the
            current map for that language; otherwise, the map will replace the
            current  map.  For example, to specify that only files with exten-
            sions of .c and .x are to be treated  as  C  language  files,  use
            "--langmap=c:.c.x";  to  also  add  files with extensions of .j as
            Java language files, specify "--langmap=c:.c.x,java:+.j".  To  map
            makefiles (.e.g files named either "Makefile", "makefile", or hav-
            ing the extension ".mak") to a  language  called  "make",  specify
            "--langmap=make:([Mm]akefile).mak".  To map files having no exten-
            sion, specify a period not  followed  by  a  non-period  character
            (e.g.  ".",  "..x",  ".x."). To clear the mapping for a particular
            language (thus inhibiting automatic generation of  tags  for  that
            language),  specify an empty extension list (e.g.  "--langmap=for-
            tran:"). To restore the default language mappings for all  a  par-
            ticular  language,  supply  the keyword "default" for the mapping.
            To specify restore the default  language  mappings  for  all  lan-
            guages, specify "--langmap=default". Note that file extensions are
            tested before file name patterns when inferring the language of  a
            file.


       --language-force=language
            By  default,  ctags automatically selects the language of a source
            file, ignoring those files whose  language  cannot  be  determined
            (see  SOURCE  FILES, above). This option forces the specified lan-
            guage (case-insensitive; either built-in or  user-defined)  to  be
            used  for  every  supplied file instead of automatically selecting
            the language based upon its extension. In  addition,  the  special
            value  auto  indicates  that  the language should be automatically
            selected (which effectively disables this option).


       --languages=[+|-]list
            Specifies the languages for which tag generation is enabled,  with
            list  containing  a  comma-separated list of language names (case-
            insensitive; either built-in or user-defined). If the  first  lan-
            guage  of list is not preceded by either a ’+’ or ’-’, the current
            list will be cleared before adding or removing  the  languages  in
            list.  Until  a ’-’ is encountered, each language in the list will
            be added to the current list. As either the ’+’  or  removed  from
            the current list, respectively. Thus, it becomes simple to replace
            the current list with a new one, or to  add  or  remove  languages
            from  the  current  list.  The actual list of files for which tags
            will be generated depends upon the language extension  mapping  in
            effect  (see  the  --langmap  option).  Note  that  all languages,
            including user-defined languages  are  enabled  unless  explicitly
            disabled using this option. Language names included in list may be
            any built-in language or one previously  defined  with  --langdef.
            The  default is "all", which is also accepted as a valid argument.
            See the --list-languages option for a complete list of the  built-
            in language names.


       --license
            Prints  a  summary of the software license to standard output, and
            then exits.


       --line-directives[=yes|no]
            Specifies whether "#line" directives should be  recognized.  These
            are  present  in  the output of preprocessors and contain the line
            number, and possibly the file name, of the original source file(s)
            from  which  the  preprocessor  output  file  was  generated. When
            enabled, this option will cause  ctags  to  generate  tag  entries
            marked  with  the  file  names and line numbers of their locations
            original source file(s), instead of their actual locations in  the
            preprocessor  output.  The  actual  file names placed into the tag
            file will have the same leading path components as the  preproces-
            sor  output  file,  since  it  is assumed that the original source
            files  are  located  relative  to  the  preprocessor  output  file
            (unless,  of  course,  the  #line  directive specifies an absolute
            path). This option is off by default. Note: This option is  gener-
            ally  only  useful when used together with the --excmd=number (-n)
            option. Also, you may have to use either the --langmap  or  --lan-
            guage-force  option  if  the  extension of the preprocessor output
            file is not known to ctags.


       --links[=yes|no]
            Indicates whether symbolic links (if  supported)  should  be  fol-
            lowed.  When  disabled, symbolic links are ignored. This option is
            on by default.


       --list-kinds[=language|all]
            Lists the tag kinds recognized for either the  specified  language
            or all languages, and then exits. Each kind of tag recorded in the
            tag file is represented by a one-letter flag, which is  also  used
            to  filter  the  tags  placed  into  the output through use of the
            --<LANG>-kinds option. Note that some languages and/or  tag  kinds
            may be implemented using regular expressions and may not be avail-
            able if  regex  support  is  not  compiled  into  ctags  (see  the
            --regex-<LANG>  option).  Each  kind listed is enabled unless fol-
            lowed by "[off]".


       --list-maps[=language|all]
            Lists the file extensions and file name patterns which associate a
            file name with a language for either the specified language or all
            languages, and then exits. See the --langmap  option,  and  SOURCE
            FILES, above.


       --list-languages
            Lists  the  names  of  the languages understood by ctags, and then
            exits.  These language names are case insensitive and may be  used
            in   the   --language-force,   --languages,   --<LANG>-kinds,  and
            --regex-<LANG> options.


       --options=file
            Read  additional  options  from  file.  As  a  special  case,   if
            --options=NONE  is  specified  as  the first option on the command
            line, it will disable the automatic reading of  any  configuration
            options from either a file or the environment (see FILES).


       --recurse[=yes|no]
            Recurse  into  directories  encountered  in  the  list of supplied
            files. If the list of supplied files is empty and no file list  is
            specified  with  the  -L  option, then the current directory (i.e.
            ".") is assumed. Symbolic links are followed. If  you  don’t  like
            these  behaviors,  either explicitly specify the files or pipe the
            output of find(1) into ctags -L- instead. Note: This option is not
            supported  on  all  platforms  at present.  It is available if the
            output of the --help option includes this option.  See, also,  the
            --exclude to limit recursion.


       --regex-<LANG>=/regexp/replacement/[kind-spec/][flags]
            The /regexp/replacement/ pair define a regular expression replace-
            ment pattern, similar in style to sed substitution commands,  with
            which  to generate tags from source files mapped to the named lan-
            guage, <LANG>,  (case-insensitive;  either  a  built-in  or  user-
            defined  language).  The  regular  expression,  regexp, defines an
            extended regular expression (roughly that used by egrep(1)), which
            is  used  to  locate a single source line containing a tag and may
            specify tab characters using \t. When a matching line is found,  a
            tag  will  be generated for the name defined by replacement, which
            generally will contain the special back-references \1  through  \9
            to  refer to matching sub-expression groups within regexp. The ’/’
            separator characters shown in the  parameter  to  the  option  can
            actually be replaced by any character. Note that whichever separa-
            tor character is used will have to be  escaped  with  a  backslash
            (’\’)  character wherever it is used in the parameter as something
            other than a separator. The regular  expression  defined  by  this
            option is added to the current list of regular expressions for the
            specified language unless the parameter is omitted, in which  case
            the current list is cleared.

            Unless  modified  by  flags,  regexp  is  interpreted  as  a Posix
            extended regular expression. The replacement should expand for all
            matching  lines  to a non-empty string of characters, or a warning
            message will be reported. An  optional  kind  specifier  for  tags
            matching  regexp may follow replacement, which will determine what
            kind of tag is reported in the "kind"  extension  field  (see  TAG
            FILE  FORMAT, below). The full form of kind-spec is in the form of
            a single letter, a comma, a name  (without  spaces),  a  comma,  a
            description,  followed by a separator, which specify the short and
            long forms of the kind value and  its  textual  description  (dis-
            played  using  --list-kinds).  Either  the  kind  name  and/or the
            description may be omitted. If kind-spec is omitted,  it  defaults
            to "r,regex". Finally, flags are one or more single-letter charac-
            ters having the following effect upon the interpretation  of  reg-
            exp:



               b   The pattern is interpreted as a Posix basic regular expres-
                   sion.

               e   The pattern is interpreted  as  a  Posix  extended  regular
                   expression (default).

               i   The  regular expression is to be applied in a case-insensi-
                   tive manner.

            Note that this option is available only if ctags was compiled with
            support for regular expressions, which depends upon your platform.
            You can determine if support for regular expressions  is  compiled
            in  by  examining  the  output of the --version option, which will
            include "+regex" in the compiled feature list.

            For more information on the regular expressions used by ctags, see
            either  the regex(5,7) man page, or the GNU info documentation for
            regex (e.g. "info regex").


       --sort[=yes|no|foldcase]
            Indicates whether the tag file should be sorted on  the  tag  name
            (default  is  yes).  Note  that the original vi(1) required sorted
            tags.  The foldcase value specifies  case  insensitive  (or  case-
            folded)  sorting.   Fast  binary searches of tag files sorted with
            case-folding will require special support  from  tools  using  tag
            files,  such  as  that found in the ctags readtags library, or Vim
            version 6.2 or higher (using "set ignorecase"). This  option  must
            appear before the first file name. [Ignored in etags mode]


       --tag-relative[=yes|no]
            Indicates  that  the file paths recorded in the tag file should be
            relative to the directory containing the  tag  file,  rather  than
            relative  to  the  current directory, unless the files supplied on
            the command line are specified with absolute  paths.  This  option
            must  appear  before  the first file name. The default is yes when
            running in etags mode (see the -e option), no otherwise.


       --totals[=yes|no]
            Prints statistics about the source files read  and  the  tag  file
            written during the current invocation of ctags. This option is off
            by default.  This option must appear before the first file name.


       --verbose[=yes|no]
            Enable verbose mode. This prints out information  on  option  pro-
            cessing  and a brief message describing what action is being taken
            for each file considered by ctags. Normally, ctags does  not  read
            command  line arguments until after options are read from the con-
            figuration files (see FILES,  below)  and  the  CTAGS  environment
            variable.  However,  if  this  option is the first argument on the
            command line, it will take effect before any options are read from
            these sources. The default is no.


       --version
            Prints a version identifier for ctags to standard output, and then
            exits. This is guaranteed to always contain the string  "Exuberant
            Ctags".




OPERATIONAL DETAILS

       As  ctags  considers  each file name in turn, it tries to determine the
       language of the file by applying the following three tests in order: if
       the  file  extension  has  been  mapped to a language, if the file name
       matches a shell pattern mapped to a language, and finally if  the  file
       is  executable  and  its  first line specifies an interpreter using the
       Unix-style "#!" specification (if supported on the platform). If a lan-
       guage  was identified, the file is opened and then the appropriate lan-
       guage parser is called to operate  on  the  currently  open  file.  The
       parser  parses  through  the file and adds an entry to the tag file for
       each language object it is written to  handle.  See  TAG  FILE  FORMAT,
       below, for details on these entries.

       This  implementation  of  ctags imposes no formatting requirements on C
       code as do  legacy  implementations.  Older  implementations  of  ctags
       tended  to rely upon certain formatting assumptions in order to help it
       resolve coding dilemmas caused by preprocessor conditionals.

       In general, ctags tries to  be  smart  about  conditional  preprocessor
       directives.  If  a  preprocessor  conditional  is  encountered within a
       statement which defines a tag, ctags follows only the first  branch  of
       that  conditional (except in the special case of "#if 0", in which case
       it follows only the last branch). The reason for this is  that  failing
       to  pursue  only  one  branch can result in ambiguous syntax, as in the
       following example:

              #ifdef TWO_ALTERNATIVES
              struct {
              #else
              union {
              #endif
                  short a;
                  long b;
              }

       Both branches cannot be followed, or braces become unbalanced and ctags
       would be unable to make sense of the syntax.

       If  the  application  of this heuristic fails to properly parse a file,
       generally due  to  complicated  and  inconsistent  pairing  within  the
       conditionals,  ctags  will  retry  the file using a different heuristic
       which does not selectively follow  conditional  preprocessor  branches,
       but  instead falls back to relying upon a closing brace ("}") in column
       1 as indicating the end of a block once  any  brace  imbalance  results
       from following a #if conditional branch.

       Ctags  will  also  try  to specially handle arguments lists enclosed in
       double sets of parentheses in order to accept the following conditional
       construct:

              extern void foo __ARGS((int one, char two));

       Any  name  immediately preceding the "((" will be automatically ignored
       and the previous name will be used.

       C++ operator definitions are specially handled. In  order  for  consis-
       tency  with  all  types  of  operators (overloaded and conversion), the
       operator name in the tag file will always be  preceded  by  the  string
       "operator " (i.e. even if the actual operator definition was written as
       "operator<<").

       After creating or appending to the tag file, it is sorted  by  the  tag
       name, removing identical tag lines.




TAG FILE FORMAT

       When  not running in etags mode, each entry in the tag file consists of
       a separate line, each looking like this in the most general case:

        tag_name<TAB>file_name<TAB>ex_cmd;"<TAB>extension_fields

       The fields and separators of these lines are specified as follows:

           1.  tag name
           2.  single tab character
           3.  name of the file in which the object associated with the tag is
               located
           4.  single tab character
           5.  EX  command used to locate the tag within the file; generally a
               search pattern (either /pattern/ or ?pattern?) or  line  number
               (see --excmd). Tag file format 2 (see --format) extends this EX
               command under certain circumstances to include a set of  exten-
               sion fields (described below) embedded in an EX comment immedi-
               ately appended to the EX command, which leaves it backward-com-
               patible with original vi(1) implementations.

       A few special tags are written into the tag file for internal purposes.
       These tags are composed in such a way that they always sort to the  top
       of  the  file.   Therefore,  the first two characters of these tags are
       used a magic number to detect a tag file for  purposes  of  determining
       whether  a  valid  tag  file  is being overwritten rather than a source
       file.

       Note that the name of each source file will be recorded in the tag file
       exactly  as  it appears on the command line. Therefore, if the path you
       specified on the command line was relative to  the  current  directory,
       then it will be recorded in that same manner in the tag file. See, how-
       ever, the --tag-relative option for how this behavior can be  modified.

       Extension  fields are tab-separated key-value pairs appended to the end
       of the EX command as a comment, as described  above.  These  key  value
       pairs  appear  in  the  general form "key:value". Their presence in the
       lines of the tag file are controlled by the --fields option. The possi-
       ble keys and the meaning of their values are as follows:


       access      Indicates  the visibility of this class member, where value
                   is specific to the language.


       file        Indicates that the tag has  file-limited  visibility.  This
                   key has no corresponding value.


       kind        Indicates  the  type,  or kind, of tag. Its value is either
                   one of the corresponding one-letter flags  described  under
                   the  various  --<LANG>-kinds options above, or a full name.
                   It is permitted (and is, in fact, the default) for the  key
                   portion of this field to be omitted. The optional behaviors
                   are controlled with the --fields option.


       implementation
                   When  present,  this  indicates  a  limited  implementation
                   (abstract  vs. concrete) of a routine or class, where value
                   is specific to the language ("virtual"  or  "pure  virtual"
                   for C++; "abstract" for Java).


       inherits    When  present,  value. is a comma-separated list of classes
                   from which this class is derived (i.e. inherits from).


       signature   When present, value. is a language-dependent representation
                   of  the  signature of a routine. A routine signature in its
                   complete form specifies the return type of  a  routine  and
                   its formal argument list. This extension field is presently
                   supported only for C-based languages and does  not  include
                   the return type.


       In  addition,  information  on  the  scope of the tag definition may be
       available, with the key portion equal to some  language-dependent  con-
       struct  name  and its value the name declared for that construct in the
       program. This scope entry indicates the scope  in  which  the  tag  was
       found. For example, a tag generated for a C structure member would have
       a scope looking like "struct:myStruct".




HOW TO USE WITH VI

       Vi will, by default, expect a tag file by the name "tags" in  the  cur-
       rent  directory.  Once  the  tag  file is built, the following commands
       exercise the tag indexing feature:

       vi -t tag   Start vi and position the cursor at the file and line where
                   "tag" is defined.

       :ta tag     Find a tag.

       Ctrl-]      Find the tag under the cursor.

       Ctrl-T      Return  to previous location before jump to tag (not widely
                   implemented).




HOW TO USE WITH GNU EMACS

       Emacs will, by default, expect a tag file by the  name  "TAGS"  in  the
       current  directory.  Once the tag file is built, the following commands
       exercise the tag indexing feature:

       M-x visit-tags-table <RET> FILE <RET>
                 Select the tag file, "FILE", to use.

       M-. [TAG] <RET>
                 Find the first definition of TAG.  The  default  tag  is  the
                 identifier under the cursor.

       M-*       Pop back to where you previously invoked "M-.".

       C-u M-.   Find the next definition for the last tag.


       For more commands, see the Tags topic in the Emacs info document.




HOW TO USE WITH NEDIT

       NEdit version 5.1 and later can handle the new extended tag file format
       (see --format). To make NEdit use the tag file, select "File->Load Tags
       File".  To  jump  to  the definition for a tag, highlight the word, the
       press Ctrl-D. NEdit 5.1 can can read multiple tag files from  different
       directories.  Setting the X resource nedit.tagFile to the name of a tag
       file instructs NEdit to automatically load that  tag  file  at  startup
       time.




CAVEATS

       Because  ctags is neither a preprocessor nor a compiler, use of prepro-
       cessor macros can fool ctags into either  missing  tags  or  improperly
       generating inappropriate tags. Although ctags has been designed to han-
       dle certain common cases, this is the single biggest cause of  reported
       problems. In particular, the use of preprocessor constructs which alter
       the textual syntax of C can fool ctags. You can work around  many  such
       problems by using the -I option.

       White  space  is treated as a separator for file names and options read
       from list files, specified using the -L  option,  and  in  filter  mode
       (specified  using  the --filter option). Therefore, it is not currently
       possible to supply file names  or  other  options  containing  embedded
       white space (spaces, etc.) through these options.

       Note that when ctags generates uses patterns for locating tags (see the
       --excmd option), it is entirely possible that the  wrong  line  may  be
       found by your editor if there exists another source line which is iden-
       tical to the line containing the  tag.  The  following  example  demon-
       strates this condition:

              int variable;

              /* ... */
              void foo(variable)
              int variable;
              {
                  /* ... */
              }

       Depending upon which editor you use and where in the code you happen to
       be, it is possible that the search pattern may locate the local parame-
       ter  declaration  in  foo()  before it finds the actual global variable
       definition, since the lines (and therefore their  search  patterns  are
       identical). This can be avoided by use of the --excmd=n option.




BUGS

       Ctags has more options than ls(1).

       When  parsing  a C++ member function definition (e.g. "className::func-
       tion"), ctags cannot determine whether the scope specifier is  a  class
       name  or  a  namespace specifier and always lists it as a class name in
       the scope portion of the extension fields. Also, if a C++  function  is
       defined  outside  of the class declaration (the usual case), the access
       specification (i.e. public, protected, or private)  and  implementation
       information (e.g. virtual, pure virtual) contained in the function dec-
       laration are not known when the tag is generated for the function defi-
       nition.   It   will,   however   be   available   for  prototypes  (e.g
       --c++-kinds=+p).

       No qualified tags are generated for language objects inherited  into  a
       class.




ENVIRONMENT VARIABLES

       CTAGS   If  this  environment  variable  exists, it will be expected to
               contain a set of default options  which  are  read  when  ctags
               starts,  after  the configuration files listed in FILES, below,
               are read, but before any command line options are read. Options
               appearing  on  the command line will override options specified
               in this variable. Only options will be read from this variable.
               Note that all white space in this variable in considered a sep-
               arator, making it impossible to pass an option  parameter  con-
               taining an embedded space. If this is a problem, use a configu-
               ration file instead.


       ETAGS   Similar to the CTAGS variable above, this variable,  if  found,
               will  be read when etags starts. If this variable is not found,
               etags will try to use CTAGS instead.


       TMPDIR  On Unix-like hosts where mkstemp() is available, the  value  of
               this  variable specifies the directory in which to place tempo-
               rary files. This can be useful if the size of a temporary  file
               becomes  too  large to fit on the partition holding the default
               temporary directory defined at compilation time.  ctags creates
               temporary  files  only if either (1) an emacs-style tag file is
               being generated, (2) the tag file is  being  sent  to  standard
               output, or (3) the program was compiled to use an internal sort
               algorithm to sort the tag files instead of the the sort utility
               of  the  operating system. If the sort utility of the operating
               system is being used, it will generally observe  this  variable
               also. Note that if ctags is setuid, the value of TMPDIR will be
               ignored.




FILES

       /ctags.cnf (on MSDOS, MSWindows only)
       /etc/ctags.conf
       /usr/local/etc/ctags.conf
       $HOME/.ctags ($HOME/ctags.cnf on MSDOS, MSWindows)
       .ctags (ctags.cnf on MSDOS, MSWindows)
              If any of these configuration files exist, each will be expected
              to  contain a set of default options which are read in the order
              listed when ctags starts, but before the CTAGS environment vari-
              able is read or any command line options are read. This makes it
              possible  to  set  up  site-wide,  personal   or   project-level
              defaults.  It is possible to compile ctags to read an additional
              configuration file before any of those shown above,  which  will
              be  indicated  if  the  output  produced by the --version option
              lists the "custom-conf" feature. Options appearing in the  CTAGS
              environment  variable  or  on  the  command  line  will override
              options specified in these files. Only options will be read from
              these  files.  Note  that the option files are read in line-ori-
              ented mode in which spaces are significant (since shell  quoting
              is  not  possible). Each line of the file is read as one command
              line parameter (as if it were quoted with single quotes). There-
              fore, use new lines to indicate separate command-line arguments.


       tags   The default tag file created by ctags.

       TAGS   The default tag file created by etags.



SEE ALSO

       The official Exuberant Ctags web site at:

              http://ctags.sourceforge.net

       Also ex(1), vi(1), elvis, or, better yet, vim, the official  editor  of
       ctags. For more information on vim, see the VIM Pages web site at:

              http://www.vim.org/




AUTHOR

       Darren Hiebert <dhiebert@users.sourceforge.net>
       http://DarrenHiebert.com/




MOTIVATION

       "Think ye at all times of rendering some service to every member of the
       human race."

       "All effort and exertion put forth by man  from  the  fullness  of  his
       heart is worship, if it is prompted by the highest motives and the will
       to do service to humanity."

              -- From the Baha’i Writings




CREDITS

       This version of ctags was originally derived from and inspired  by  the
       ctags program by Steve Kirkendall <kirkenda@cs.pdx.edu> that comes with
       the Elvis  vi  clone  (though  virtually  none  of  the  original  code
       remains).

       Credit  is  also  due Bram Moolenaar <Bram@vim.org>, the author of vim,
       who has devoted so much of his time and energy both to  developing  the
       editor as a service to others, and to helping the orphans of Uganda.

       The section entitled "HOW TO USE WITH GNU EMACS" was shamelessly stolen
       from the info page for GNU etags.



Darren Hiebert                   Version 5.5.4                        CTAGS(1)

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