I'd like to automatically kill a command after a certain amount of time. I have in mind an interface like this:
% constrain 300 ./foo args
Which would run "./foo" with "args" but automatically kill it if it's still running after 5 minutes.
It might be useful to generalize the idea to other constraints, such as autokilling a process if it uses too much memory.
Are there any existing tools that do that, or has anyone written such a thing?
ADDED: Jonathan's solution is precisely what I had in mind and it works like a charm on linux, but I can't get it to work on Mac OSX. I got rid of the SIGRTMIN which lets it compile fine, but the signal just doesn't get sent to the child process. Anyone know how to make this work on Mac?
[Added: Note that an update is available from Jonathan that works on Mac and elsewhere.]