in_array.sh

#!/usr/bin/env bash

# As passing an array by value is not possible (that I know) this function
# requires that the array passed has been expanded (@)
function in_array() {
  # Require both needle and haystack
	if [ -z "$1" -o -z "$2" ]; then
		return;
	fi
	# Use the first argument as needle
	local needle="${1}"
	# Then shift the arguments so that only the haystack remains
	shift
	# Create a new array from all remaining arguments
	local array=(`echo "${@}"`)
	local i
	# Iterate through the array and return true (0) on match
	for i in "${array[@]}"
	do
		if [ "${i}" = "${needle}" ]; then
			return 0
		fi
	done
	return 1
}