Question

I’ve got two commands foo and bar.

foo runs for a long time without stdin or stdout/stderr activity. bar is a client of foo and runs with stdout/stderr but no stdin activity.

I’d like to run them from one shell, being able to kill both with ctrl-c, and to see the output from bar as it occurs.

i.e. something like this sequence

foo & bar kill -9

but without having to manually do the kill – instead it just happens on ctrl-c

is there a way of scripting this?

thanks

Answer 1

Don’t use kill -9.

You want to trap on EXIT, not on INT.

trap 'kill $fooPid $barPid' EXIT foo & fooPid=$! bar & barPid=$! wait 

This solution will always make sure to terminate foo and bar, whatever the reason for it exiting (excluding it being SIGKILL‘ed).

If you want to avoid keeping PIDs (which has some race condition issues) you can do this instead:

trap 'kill $(jobs -p)' EXIT foo & bar & wait 

That’s a better (and cleaner!) solution if your script has no other jobs.

Ps: These solutions mean foo and bar can write to your terminal (your script’s stdout), but neither can read from stdin. If you need either foo or bar to read from stdin, the solution becomes a bit more complex.