Runs a process for a given time

runstop.sh

#!/bin/bash -eu
#
# Runs a process for given time (timeout format is same as in
# sleep(1)) and terminates it with SIGTERM after timeout occurs.
#
# Author: Joel Lehtonen <joel.lehtonen@iki.fi>

# Keeps some parameters and alters positional parameters
TIMEOUT=$1
PROG=$2
shift 2

# Somewhat dangerous trick begins: It forks subshell which kills the
# parent. The dangerous part is that if the parent dies before timeout
# and a new process has reused the PID. In that case it kills an
# outsider. I'm sorry.
(
    sleep "$TIMEOUT"
    # Kill -s 0 doesn't kill but returns failure if PID is dead. That
    # terminates this script because we have -e option.
    kill -s 0 $$ 2>/dev/null
    echo "Timeout of $TIMEOUT reached"
    kill $$
) &

# Replaces current shell with the desired process. To allow running of
# programs requiring tty access, we have to do it this way.
exec "$PROG" "$@"