how to add other user in a group code example
Example 1: add user to group
usermod -a -G examplegroup exampleusername
Example 2: 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