groups
display current group names
TLDR
Print group memberships for the current user
$ groups
Print group memberships for a list of users
$ groups [username1 username2 ...]
SYNOPSIS
groups [user]
DESCRIPTION
The groups command displays the current group names or ID values. If the value does not have a corresponding entry in /etc/group, the value will be displayed as the numerical group value. The optional user parameter will display the groups for the named user.
NOTE
Systems which do not support concurrent group sets will have the information from /etc/group reported. The user must use newgrp or sg to change his current real and effective group ID.
FILES
/etc/group
Group account information.
SEE ALSO
newgrp(1), getgid(2), getgroups(2), getuid(2).