I'm trying to spawn an SSH from my bash profile script that runs in the background for connection sharing (via its control socket). The problem I'm running into is a reliable way to ensure the SSH doesn't stay running once the TTY is closed (or more directly; once the parent bash shell has exited).
I know the shell can run commands (to terminate SSH) when it exits gracefully, but I'm trying to handle all possible scenarios where the shell doesn't get a chance to shut things down.
Is there a clever way I can do this?
The best idea I've had is
ssh -o PermitLocalCommand=yes -o LocalCommand='cat >/dev/null; kill $PPID' $HOST &
But this won't work because I need the command to only background once it has successfully started. Alternatively, I can't use
-fN instead of the shell's
& because the SSH
-f only backgrounds after the
LocalCommand has completed.
Also I'm trying to avoid running any command on the remote host. Otherwise I could probably do something like
ssh -fN $HOST 'cat >/dev/null'