which user group linux code example

Example 1: linux add user to group

# Change the primary group a user is assigned to, note the -g here.
# When you use a lowercase g, you assign a primary group. When you 
# use an uppercase -G you assign a new secondary group.
usermod -g groupname username

Example 2: how to check user in group linux

# to see the group joined by current user
$ id 

groups
groups {USERNAME}
groups vivek

Example 3: linux user groups

groups $username