rexec



REXEC(1)                                                              REXEC(1)




NAME

       rexec -- remote execution client for an exec server


SYNOPSIS

       rexec [ -abcdhns -l username -p password ] host command


DESCRIPTION

       Rexec  calls  the  rexec(3)  routine  to act as a client for the remote
       host’s rexecd(8) server.

       It asks that ‘‘command’’ be run  on  the  host  computer,  using  user-
       name/password authentication. See rexec(3) and rexecd(8) for details of
       the protocol.


OPTIONS

       Rexec accepts several options, but only three are  likely  to  be  very
       useful:

       -l username

              Set the log-in name on the remote host to username.

       -p password

              Provide  the  password for the remote account.  The command line
              argument will be blanked after being parsed, to prevent it  from
              being  seen with ps(1).  However, it is still not very secure to
              type the password on the command line.  In particular,  be  sure
              that the shell’s history file is protected.

       -n     Explicitly prompt for name and password, even if provided in the
              environment, in the $HOME/.netrc file, or in  the  environmental
              variables REXEC_USER and REXEC_PASS.

       Other  options  that might be useful with non-standard remote exec dae-
       mons, or to debug connections:

       -a     Do not set up an auxiliary channel for standard error from  com-
              mand;  the  remote  standard  error  and  output  are  then both
              returned on the local standard output.  By default,  rexec  asks
              that a separate channel be set up for diagnostic output from the
              remote command.

       -b     Use signal handling as in BSD rsh(1).  Only the signals  SIGINT,
              SIGQUIT,  and SIGTERM are echoed to the remote process.  They do
              not remain raised locally, so rexec waits for the remote command
              to  shutdown  its  side  of the socket.  Also, CNTRL-Z will only
              suspend execution locally--the remote command  may  continue  to
              run.

       -c     Do  not  close  remote  standard input when local standard input
              closes.  Normally the standard input to the  remote  command  is
              closed when the local standard input is closed.

       -d     Turn on debugging information. In particular the command sent to
              the remote host will be echoed.

       -h     Print a usage message.

       -s     Do not echo signals received by the rexec onto the  remote  pro-
              cess.   Normally,  signals which can be trapped are passed on to
              the remote process; then, when  you  type  CNTRL-C,  the  remote
              process terminates as well.


USERNAME AND PASSWORD

       Rexec(1) searches for the username and password in the following order:

              1. If -n is given on the command line, the user will  always  be
              prompted  for  both,  even if they are also given on the command
              line.

              2. The command line will be parsed

              3. If the environmental variables REXEC_USER or  REXEC_PASS  are
              defined, they will define the username or password.

              4.  The  $HOME/.netrc  file  will be searched.  See ftp(1) for a
              description of this file’s format.

              5. Finally, the user will be prompted if either the username  or
              password remains undefined.



SECURITY

       Users  of  this  command  should be aware that rexec(3) transmits their
       password to the remote host clear text, not encrypted.  If the  network
       is not secure to the remote host, the password can be comprimised.



SIGNALS

       Without  the  -b option, all signals which can be handled are echoed to
       the remote process.  Afterwards, however, they  remain  raised  in  the
       local  process.   Typically,  this  means that rexec(1) will exit after
       receiving a fatal signal, even if the remote process  has  arranged  to
       handle or ignore it.

       Differing  operating  systems use differing signal numbers; for example
       AIX and SunOS use 18 for SIGTSTP (^Z), while Linux uses 20.  Therefore,
       it  may  have a different effect remotely than locally.  In particular,
       typing CNTL-Z may not suspend the execution of the remote process.


EXAMPLE

       rexec othermachine cat ">remote_file; date" <local_file

       will send local_file to the othermachine as remote_file.



BUGS

       Please send bug reports, system incompatibilities, and  job  offers  to
       the author.


SEE ALSO

       rexec(3), rexecd(8), rsh(1)


AUTHOR

       Michael Sadd
       mas22@cornell.edu
       http://www.tc.cornell.edu/~sadd/

       Thanks  to  Orange  Gopher  (2/10/97)  and  Johannes  Plass (plass@dip-
       mza.physik.uni-mainz.de, Oct. 17 1996) for useful suggestions.



                               February 14, 1997                      REXEC(1)

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