bash - How do I kill a backgrounded/detached ssh session?

Question

I am using the program synergy together with an ssh tunnel

It works, i just have to open an console an type these two commands:

ssh -f -N -L localhost:12345:otherHost:12345 otherUser@OtherHost
synergyc localhost

because im lazy i made an Bash-Script which is run with one mouseclick on an icon:

#!/bin/bash
ssh -f -N -L localhost:12345:otherHost:12345 otherUser@OtherHost
synergyc localhost

the Bash-Script above works as well, but now i also want to kill synergy and the ssh tunnel via one mouseclick, so i have to save the PIDs of synergy and ssh into file to kill them later:

#!/bin/bash

mkdir -p /tmp/synergyPIDs || exit 1
rm -f /tmp/synergyPIDs/ssh || exit 1
rm -f /tmp/synergyPIDs/synergy || exit 1

[ ! -e /tmp/synergyPIDs/ssh ] || exit 1
[ ! -e /tmp/synergyPIDs/synergy ] || exit 1

ssh -f -N -L localhost:12345:otherHost:12345 otherUser@OtherHost
echo $! > /tmp/synergyPIDs/ssh
synergyc localhost
echo $! > /tmp/synergyPIDs/synergy

But the files of this script are empty.

How do I get the PIDs of ssh and synergy?
(I try to avoid ps aux | grep ... | awk ... | sed ... combinations, there has to be an easier way.)

Answer 1

Quick summary: Will not work.

My first idea is that you need to start the processes in the background to get their PIDs with $!.

A pattern like

some_program &
some_pid=$!
wait $some_pid

might do what you need... except that then ssh won't be in the foreground to ask for passphrases any more.

Well then, you might need something different after all. ssh -f probably spawns a new process your shell can never know from invoking it anyway. Ideally, ssh itself would offer a way to write its PID into some file.