Fernando Ipar

Running commands from the shell with a timeout

Sometimes, in a shell script, you need to run a command that might go on forever (or an amount of time long enough to be called forever) due to poor coding of the software and wrong external conditions (network down or overloaded, overloaded system, a changed private key, etc).

In order to avoid this situations, here’s a small shell script that will execute any command with a guaranteed timeout:

#!/bin/bash

timeout=$1
command=$2

check_pid_name()
{
        command=$1
        childpid=$2
        [ -d /proc/$childpid ] || return 1
        [ $(grep -c $command /proc/$childpid/cmdline 2>/dev/null) -gt 0 ] && return 0 || return 1
}

[ -z "$command" ] && echo "I need a command to run">&2 && exit 1

[ $# -eq 2 ] && shift || shift 2

$command $* &
childpid=$!

sleep $timeout 

check_pid_name $command $childpid && {
        kill $childpid
        sleep 0.1
        check_pid_name $command $childpid && kill -9 $childpid
        echo "$command $* timed out"
}

As you can see, it’s quite simple. You just have to start the desired command in the background, sleep for the timeout, and then kill the process if it’s still running.

Yes, this script has a defect, all the commands will wait $timeout to run, but that’s easy to solve. I’ll post an improved (but slightly more complex) version in my next post.

Related posts:

1. Running commands from the shell with a timeout (pt 2) Here’s an improved version of the safecmd script. This one...
2. Generating random salts from bash From the ‘just because it can be done’ column, here...
3. Piping data to multiple processes Here’s a simple shell script to stream data to multiple...

Related posts brought to you by Yet Another Related Posts Plugin.

Comments are closed.