I learned a little bit about how to administer users on a linux box this week. I also keep a log file which I call linux.txt of stuff I learn about linux that I want to remember for reference but I might not remember or might be hard to find again. Here’s what I added to it about the user administration.
chsh user /dev/null — change the users shell to whatever you want
adduser instead of useradd. adduser adds all the necessary stuff
edit /etc/groups for groups
edit /etc/passwd for changing peoples shells