rexec -- remote execution client for an exec server
rexec [ -abcdhns -l username -p password ] host command
Rexec calls the rexec(3) routine to act as a client for the remote host's rexecd(8)
It asks that ``command'' be run on the host computer, using username/password authentica-
tion. See rexec(3) and rexecd(8) for details of the protocol.
Rexec accepts several options, but only three are likely to be very useful:
Set the log-in name on the remote host to username.
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 daemons, or to debug con-
-a Do not set up an auxiliary channel for standard error from command; 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
-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
-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 process. Normally, sig-
nals 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
5. Finally, the user will be prompted if either the username or password remains
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.
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
rexec othermachine cat ">remote_file; date" <local_file
will send local_file to the othermachine as remote_file.
Please send bug reports, system incompatibilities, and job offers to the author.
rexec(3), rexecd(8), rsh(1)
Thanks to Orange Gopher (2/10/97) and Johannes Plass (email@example.com,
Oct. 17 1996) for useful suggestions.
February 14, 1997 REXEC(1)