This is not directly possible from sudo itself, but it is possible with some hackish technique.

sudo_timeout.sh :

#!/bin/bash



timeout=10 #seconds



set -m



echoerr() { echo "$@" 1>&2; }



keep_eye_on() {

    pid=$1

    time_passed=0

    while kill -0 $pid &> /dev/null; do

        sleep 1

        let time_passed=time_passed+1

        if [ $time_passed -ge $timeout ]; then

            echoerr "Timeout reached."

            kill -9 $pid

            exit 1

        fi

    done

}



if [ -z "$1" ]; then

    echoerr "Please specify a process to run!" 

    exit 1

fi;



sudo $@ &

pid=$!



keep_eye_on $pid &

while true; do

    if kill -0 $pid &> /dev/null; then

        fg sudo > /dev/null; [ $? == 1 ] && break;

    else

        break

    fi

done

The timeout variable holds the timeout in seconds to wait prior killing the sudo process that is asking for password.

Usage:

./sudo_timeout.sh <command>

Example:

./sudo_timeout.sh ls -al

In case the timeout is reached you get:

alex@MaD-pc:~$ ./sudo_timeout.sh ls -al

[sudo] password for alex: Timeout reached.

./sudo_timeout.sh: line 34: 14583 Killed                  sudo $@

In case you type in your password prior the timeout, then the command executes normally.

Disclaimer: The above is tested with simple commands like ls and nano, both with and without arguments, but I cannot guarantee that it will work in every case because I haven't thoroughly tested it, it's just something I came up with.