How can I timeout a forked process that might hang?

Question

I am writing a Perl script that will write some inputs and send those inputs to an external program. There is a small but non-zero chance that this program will hang, and I want

Answer 1

The only way SIGKILL can be ignored is if the process is stuck in a system call which is uninterruptible. Check the state of the hung process (with ps aux) if the state is D, then the process can't be killed.

You might also want to check that the function is being called by outputting something from it.