timeout.sh - run a command with a time limit

timeout.sh

#!/bin/sh

duration="${1}"; shift

if [ "$#" -eq 0 ] || [ "$(echo "$duration" | tr -dc '0-9')" != "$duration" ]; then
  echo "Usage: $0 DURATION COMMAND [ARG]..."
  exit 1
fi

( "$@" &
  child_pid=$!
  trap -- "" SIGTERM

  ( sleep $duration
    kill $child_pid 2> /dev/null ) &

  wait $child_pid
)

unset -f duration child_pid