This script will run on a linux server which provides file sharing for windows (samba), linux (NIS) and Xterminal (ltsp) in a french high school. Students use both linux and windows (Windows in the library, Windows or linux in my classroom...), so i thought a cgi script is more simple for them because the way to change the password is the same. Another reason is that when I create the accounts, the password used is the last name, the login name used is the first name. So, they must quickly change the password. And, as I am a (lazy) teacher, I can't be here every day to do that task.