#!/usr/bin/env bash

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

# -h case
if [[ "$1" -eq "-h" ]]; then
	echo "$USAGE"; exit 0 

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

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

# -e <pid> case
elif [[ "$1" -eq "-e" && "$2" =~ ^-?[0-9]+$ ]]; then
	if `ps $2 > /dev/null 2>&1`; then
		echo "you win!"; exit 0;

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

# -s <pid> <regex> case
elif [[ "$1" -eq "-s" && "$2" =~ ^-?[0-9]+$ ]]; then
	if `ps $2 > /dev/null 2>&1`; then
		echo "you win!"; exit 0;

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

else
	echo "$USAGE"; exit 1
fi