Guide to unix usergroups

This page is not so much of a guide as a reference to some useful commands.

Description	Command
Listing available groups	groups
Creating a group	groupadd groupname
Adding a user to a group	adduser username groupname
Listing group members	getent group groupname
Listing a users groups	groups username or grep username /etc/group
Removing a user from a group	gpasswd -d username group

Notes

when using /etc/group, the file is in the following format (without spaces)

groupname : password : groupid : members