Timeout a command in bash without unnecessary delay

You are probably looking for the timeout command in coreutils. Since it's a part of coreutils, it is technically a C solution, but it's still coreutils. info timeout for more details.Here's an example:

timeout 5 /path/to/slow/command with options

I think this is precisely what you are asking for:

http://www.bashcookbook.com/bashinfo/source/bash-4.0/examples/scripts/timeout3

#!/bin/bash## The Bash shell script executes a command with a time-out.# Upon time-out expiration SIGTERM (15) is sent to the process. If the signal# is blocked, then the subsequent SIGKILL (9) terminates it.## Based on the Bash documentation example.# Hello Chet,# please find attached a "little easier"  :-)  to comprehend# time-out example.  If you find it suitable, feel free to include# anywhere: the very same logic as in the original examples/scripts, a# little more transparent implementation to my taste.## Dmitry V Golovashkin <Dmitry.Golovashkin@sas.com>scriptName="${0##*/}"declare -i DEFAULT_TIMEOUT=9declare -i DEFAULT_INTERVAL=1declare -i DEFAULT_DELAY=1# Timeout.declare -i timeout=DEFAULT_TIMEOUT# Interval between checks if the process is still alive.declare -i interval=DEFAULT_INTERVAL# Delay between posting the SIGTERM signal and destroying the process by SIGKILL.declare -i delay=DEFAULT_DELAYfunction printUsage() {    cat <<EOFSynopsis    $scriptName [-t timeout] [-i interval] [-d delay] command    Execute a command with a time-out.    Upon time-out expiration SIGTERM (15) is sent to the process. If SIGTERM    signal is blocked, then the subsequent SIGKILL (9) terminates it.    -t timeout        Number of seconds to wait for command completion.        Default value: $DEFAULT_TIMEOUT seconds.    -i interval        Interval between checks if the process is still alive.        Positive integer, default value: $DEFAULT_INTERVAL seconds.    -d delay        Delay between posting the SIGTERM signal and destroying the        process by SIGKILL. Default value: $DEFAULT_DELAY seconds.As of today, Bash does not support floating point arithmetic (sleep does),therefore all delay/time values must be integers.EOF}# Options.while getopts ":t:i:d:" option; do    case "$option" in        t) timeout=$OPTARG ;;        i) interval=$OPTARG ;;        d) delay=$OPTARG ;;        *) printUsage; exit 1 ;;    esacdoneshift $((OPTIND - 1))# $# should be at least 1 (the command to execute), however it may be strictly# greater than 1 if the command itself has options.if (($# == 0 || interval <= 0)); then    printUsage    exit 1fi# kill -0 pid   Exit code indicates if a signal may be sent to $pid process.(    ((t = timeout))    while ((t > 0)); do        sleep $interval        kill -0 $$ || exit 0        ((t -= interval))    done    # Be nice, post SIGTERM first.    # The 'exit 0' below will be executed if any preceeding command fails.    kill -s SIGTERM $$ && kill -0 $$ || exit 0    sleep $delay    kill -s SIGKILL $$) 2> /dev/null &exec "$@"

This solution works regardless of bash monitor mode. You can use the proper signal to terminate your_command

#!/bin/sh( your_command ) & pid=$!( sleep $TIMEOUT && kill -HUP $pid ) 2>/dev/null & watcher=$!wait $pid 2>/dev/null && pkill -HUP -P $watcher

The watcher kills your_command after given timeout; the script waits for the slow task and terminates the watcher. Note that wait does not work with processes which are children of a different shell.

Examples:

• your_command runs more than 2 seconds and was terminated

your_command interrupted

( sleep 20 ) & pid=$!( sleep 2 && kill -HUP $pid ) 2>/dev/null & watcher=$!if wait $pid 2>/dev/null; then    echo "your_command finished"    pkill -HUP -P $watcher    wait $watcherelse    echo "your_command interrupted"fi

• your_command finished before the timeout (20 seconds)

your_command finished

( sleep 2 ) & pid=$!( sleep 20 && kill -HUP $pid ) 2>/dev/null & watcher=$!if wait $pid 2>/dev/null; then    echo "your_command finished"    pkill -HUP -P $watcher    wait $watcherelse    echo "your_command interrupted"fi