#!/bin/sh
# Kill the pid referenced by a pidfile, if any.

progname="$0"

log() {
  echo "$@" >&2
}

die() {
  log "Fatal:" "$@"
  exit 1
}

usage() {
  log "Usage: $progname [-s signal] <pidfile>"
  exit 99
}

while getopts "hs:" option
do
  case "$option" in
  s)
    signal="$OPTARG"
    ;;
  h|\?|*)
    usage
    exit 1
    ;;
  esac
done

# the rest are non-option arguments
shift $(($OPTIND-1))


pidfile="$1"
if [ -z "$pidfile" ]; then
  usage
fi

[ -e "$pidfile" ] || exit 0

read pid junk <"$pidfile"

[ -n "$pid" ] || die "'$pidfile' exists but has no pid inside"
[ "$pid" -gt 1 ] || die "'$pidfile' pid is '$pid'; must be > 1"

if [ -n "$signal" ]; then
  kill -"$signal" "$pid" 2>/dev/null
else
  # By default, kill the process
  kill -15 "$pid" 2>/dev/null
  for d in $(seq 20); do
    kill -0 "$pid" 2>/dev/null || break
    sleep 0.1
  done
  kill -9 "$pid" 2>/dev/null

  # return an error if the process *does* exist
  ! kill -0 "$pid" 2>/dev/null
fi