How to use launchd to ensure an application is running?

Question

I use Quicksilver, which is a nifty program that really speeds up my work. I've set it to launch when I log in.

However, since Snow Leopard, it's become a bit less stable, and once in a while, it crashes. And obviously, it won't restart by itself.

I'm pretty sure I can use launchd to ensure it's always running when I'm logged in. Is there a good guide/example of how to make sure a process restarts when it's killed/terminated/crashed with it?

Answer 1

Googling for launchd quicksilver I got this:

http://www.zzamboni.org/brt/2008/01/28/using-launchd-to-immortalize-quicksilver-howto/index.html

...which looks right.

See man launchd.plist for more information about the keys you can put into a launchd plist file to control when and how launchd launches or re-launches processes.

Answer 2

I have not tried this, as I don't have a mac, but I've been told it has bash as default shell these days. You could possibly get this going with a bash-script that you execute on logon by any means.

What it basically does is execute the given command repeatedly until it returns zero, which means it closed normally.

#!/bin/bash

RETVAL=1
until [ $RETVAL -eq 0 ]; do
    # change this to whatever is used to launch quicksilver
    /Applications/Quicksilver.app/Quicksilver

    RETVAL=$?
done

Edit: To clarify, put that in an empty text-file (optionally with an .sh-extension) and give it execute permissions (chmod +x filename) and it should work.