Kinda hacky, but it works. Doesn't work if you have other foreground processes (please help me fix this!)
sleep TIMEOUT & SPID=${!}; (YOUR COMMAND HERE; kill ${SPID}) & CPID=${!}; fg 1; kill ${CPID}
Actually, I think you can reverse it, meeting your 'bonus' criteria:
(YOUR COMMAND HERE & SPID=${!}; (sleep TIMEOUT; kill ${SPID}) & CPID=${!}; fg 1; kill ${CPID}) < asdf > fdsa
I think this is precisely what you are asking for:
http://www.bashcookbook.com/bashinfo/source/bash-4.0/examples/scripts/timeout3
In 99% of the cases the answer is NOT to implement any timeout logic. Timeout logic is in nearly any situation a red warning sign that something else is wrong and should be fixed instead.
Is your process hanging or breaking after n seconds sometimes? Then find out why and fix that instead.
As an aside, to do strager's solution right, you need to use wait "$SPID" instead of fg 1, since in scripts you don't have job control (and trying to turn it on is stupid). Moreover, fg 1 relies on the fact that you didn't start any other jobs previously in the script which is a bad assumption to make.
How would you run this timeout3 if the program has pipes in it?
Like, I am running
echo| openssl s_client abc| ./programx | grep xyz | cut abc | grep cde > /tmp/file
openssl s_client has no timeout... If I try
./timeout3 -t 10 echo| openssl s_client abc| ./programx | grep xyz | cut abc | grep cde > /tmp/file
It will go for more than 10 seconds without timeouting.. Any ideas?
See also the http://www.pixelbeat.org/scripts/timeout script the functionality of which has been integrated into newer coreutils
I prefer "timelimit", which has a package at least in debian.
http://devel.ringlet.net/sysutils/timelimit/
It is a bit nicer than the coreutils "timeout" because it prints something when killing the process, and it also sends SIGKILL after some time by default.