Timeout on shell command.

[Maarten Litmaath]

In article <3716 at sactoh0.UUCP>,
	jak at sactoh0.UUCP (Jay A. Konigsberg) writes:
)...
)command &                # execute in background

What if the command is supposed to run in the _foreground_?
The following timeout shell script can be easily converted to a C program
if desired.
--------------------cut here--------------------
#!/bin/sh
# @(#)timeout 6.2 90/03/01 Maarten Litmaath

prog=`basename $0`
usage="Usage: $prog [-signal] [timeout] [:interval] [+delay] [--] <command>"

SIG=-KILL	# default signal sent to the process when the timer expires,
		# unless a delay option has been given: then it is -TERM
sigopt=0
timeout=60	# default timeout
interval=15	# default interval between checks if the process is still alive
delay=		# (if specified) the delay between posting the given signal and
		# destroying the process (kill -KILL)

while :
do
	case $1 in
	--)
		shift
		break
		;;
	-*)
		SIG=$1
		sigopt=1
		;;
	[0-9]*)
		timeout=$1
		;;
	:*)
		EXPR='..\(.*\)'
		interval=`expr x"$1" : "$EXPR"`
		;;
	+*)
		EXPR='..\(.*\)'
		delay=`expr x"$1" : "$EXPR"`
		case $sigopt in
		0)
			SIG=-TERM
		esac
		;;
	*)
		break
	esac
	shift
done

case $# in
0)
	echo "$usage" >&2
	exit 2
esac

(
	for t in $timeout $delay
	do
		while test $t -gt $interval
		do
			sleep $interval
			kill -0 $$ || exit
			t=`expr $t - $interval`
		done
		sleep $t
		kill $SIG $$ && kill -0 $$ || exit
		SIG=-KILL
	done
) 2> /dev/null &

exec "$@"
--
   "UNIX was never designed to keep people from doing stupid things, because
    that policy would also keep them from doing clever things."  (Doug Gwyn)