What command do you use to add a new group in Linux?

To add a new group in Linux, the command used is groupadd. This command is specifically designed to create new groups in the system. When invoked, it allows an administrator to designate a unique name for the group and assign it specific settings, such as a group ID (GID) if desired.

The other commands mentioned serve different purposes: groupmod is used to modify an existing group; groupdel is used to delete an existing group from the system; and useradd is intended for creating new user accounts rather than groups. The functionality of each command is distinct, with groupadd being the only one specifically focused on the creation of groups, making it the correct choice for this question.