• Print groups for the current process:
  

  $ groups
  mtitek group1 group2

• You can print the groups of a specific users:
  

  $ groups mtitek mtitek1
  mtitek : mtitek group1 group2
  mtitek1 : mtitek1

Usage: groupadd [options] GROUP

Options:
  -f, --force  exit successfully if the group already exists

• Create a group named "newgroup".
  

  $ sudo groupadd newgroup
  
  $ cat /etc/group | grep newgroup
  newgroup:x:1005:

• Delete the group "newgroup":

  $ sudo groupdel newgroup