Linux: Find Out My Group Name [ Group Memberships ]

How do I find out the group name under Linux operating systems using bash shell prompt? How do I display group information for the specified USERNAME under Linux?

Open a command-line terminal (select Applications > Accessories > Terminal), and then type the following command to list your group ownership i.e. display the groups a user is in:
$ users
Sample outputs:

vivek adm dialout cdrom plugdev lpadmin netdev admin sambashare libvirtd

vivek user is part of the above groups. To display group memberships for a user called tom, enter:
$ users userName
$ users tom
To print the primary group membership for a user called tom, enter:
$ id -g -n tom
To print the secondary group membership for a user called tom, enter:
$ id -G -n tom
You can also search /etc/group file as follows using the grep command:
$ grep Username /etc/group
$ grep vivek /etc/group
Sample outputs:

adm:x:4:vivek
dialout:x:20:vivek
cdrom:x:24:vivek
plugdev:x:46:vivek
lpadmin:x:105:vivek
netdev:x:112:vivek
admin:x:119:vivek
vivek:x:1000:
sambashare:x:122:vivek
libvirtd:x:125:vivek

See also:

If you need assistance with Linux groups membership related commands, turn to the man page first. It will give you detailed information, parameters and switches for the following commands:
$ man id
$ man groups
$ man 5 group