Follow ZDNET: Add us as a preferred source on Google. The usermod command is short for user modification, and, as the name implies, allows you to modify various aspects of a user account. For a Linux ...
Use "sudo usermod -a -G example_group example_user" to add a user to a group. To add a user to multiple groups at once, separate groups by commas, like "sudo usermod -a -G group1,group2,group3 example ...