pidwatch - Run a command and if another PID exits, kill the command


  pidwatch [--cd I<cd>] --host <host> --pid <pid>  args[....]
  pidwatch [--cd I<cd>] --host <host> --pid <pid> --foreground <pid>


Chdir to the specified directory, if specified and possible, then run the arguments as a command in the foreground. When the foreground process exits, return its exit status. This is basically the same as running the command directly.

In the background, watch the specified pid on the specified host. If pidstatd is running on the specified host, and the specified pid goes away, kill the foreground command.

Alternatively pass the PID of any process with --foreground. When the foreground process exits, the background job exits; if the specified watched PID exits, the foreground pid is killed.

Common usage is to kill remote rsh children when a parent is kill -9ed. An example Perl application would invoke:

    system("rsh \$remote_host pidwatch"
           ." --cd \$ENV{PWD} --host \$ENV{HOST} --pid \$\$"

Another usage is as a "barrier" to start the new step in a script when another process completes. Just use a sleep with a appropriate timeout value:

    pidwatch --host HOST --pid PID sleep 9999999
    echo PID has completed, do whatever is next



All non switch arguments after the switches are passed to /bin/sh as a -c argument. Thus passing "a && b" to pidwatch will result in pidwatch executing "/bin/sh -c 'a && b'".

--cd dir

Directory to chdir to.


Displays this message and program version and exits.

--host host

Hostname to check for specified pid on. pidstatd must be running on that host to have this program be useful.

--killer program

Program to use instead of kill when it's time to terminate the pid. Will be passed arguments as if it was /bin/kill (program signame pid).

--foreground pid

Process ID to be killed when watched process exits. Used to watch a preexisting PID, instead of launching commands under a shell.

--pid pid

Process ID to watch. When this pid exits, the program will kill the foreground process.

--port port

Port of pidstatd server on remote host.

--signal signame

Signal number/name to send to process on remote PIDs death. Defaults to -HUP.


Displays program version and exits.


The latest version is available from CPAN and from

Copyright 2002-2022 by Wilson Snyder. This package is free software; you can redistribute it and/or modify it under the terms of either the GNU Lesser General Public License Version 3 or the Perl Artistic License Version 2.0.


Wilson Snyder <>


IPC::Locker, IPC::PidStat, pidstat, pidstatd, pidwatch, uriexec