swuser

#!/bin/bash

#
# swuser - Switch users via Mac OS X's Fast User Switching 
#
# Originally via Schoun Reagan, but later 
# http://www.macosxhints.com/article.php?story=20031102031045417
#
# v0.1   2006-10-18 - Morgan Aldridge <morgant@makkintosshu.com>
#                     Initial release
# v0.2   2010-12-27 - Morgan Aldridge
#                     Renamed to 'swuser', added usage instructions, options
#                     for switching to login window, user by name, or user by ID.
#

# global variables
user=$(whoami)
id=$(id -u $user)
cgsession="/System/Library/CoreServices/Menu Extras/User.menu/Contents/Resources/CGSession"

# print usage instructions (help)
function usage() {
	printf "Usage: swuser [options [username|useried]]\n"
	printf "  -h            print these usage instructions\n"
	printf "  -l            switch to the login window\n"
	printf "  -n            switch to a different user by user name\n"
	printf "  -u            switch to a different user by user id\n"
}

function check_id() {
	if (( $1 == $2 )); then
		printf "Sorry, you can't switch to yourself.\n"
		exit 1;
	fi
}

# exit with an error if being run from screen
if [ "$STY" != "" ]; then
	printf "Sorry, swuser doesn't work from within screen. I know, I hate it too!\n"
	exit 1;
fi

# see if any arguments were passed in
if [ $# -gt 0 ]; then
	# if so, step through them all and process them
	while [ $# -gt 0 ]; do
		# see if the user requested help
		if [ "$1" = "-h" ]; then
			usage
			exit;
		# handle switch to login window
		elif [ "$1" = "-l" ]; then
			"$cgsession" -suspend
			shift
		# handle switching to another user by name
		elif [ "$1" = "-n" ]; then
			shift
			new_id=$(id -u "$1")
			check_id $id $new_id
			"$cgsession" -switchToUserID $(id -u "$1")
			shift
		# handle switch to another user by id
		elif [ "$1" = "-u" ]; then
			shift
			check_id $id $1
			"$cgsession" -switchToUserID $1
			shift
		fi
	done
else
	printf "No switch user action specified.\n\n"
	usage
fi