#!/usr/bin/env bash

USAGE="usage: ./process-pid.sh {[-h, -a], [-f, -e] <pid>}, -s <regexp>"

if [ -z "$1" ]; then
	echo "$USAGE"; exit 1

elif [[ "$1" =~ ^-?[0-9]+$ ]]; then # unportable :(
	if `ps $1 > /dev/null 2>&1`; then
		echo "you win!"; exit 0

	else
		echo -ne "invalid pid\n$USAGE"; exit 1
	fi

elif [[ "$1" -eq "-h" ]]; then
	echo "$USAGE"; exit 0 
fi