groupadd

Basics

groupadd is a command to add a new user-group to a Linux system.

On some systems, this command is not on the search path for executables, so you may need to use whereis to find it.
This command usually requires root access.
A system account is generally an account that isn't logged into or used by users. Examples are audio, video, cdrom, dialout, scanner, staff, etc. It's not clear exactly what special handling these accounts may be receiving with Red Hat; see Questions.

What special handling do system accounts receive under Red Hat? (See "notes" for known information about system accounts.)
The action of the -r option ("add a system account") is a little unclear -- does it create a system-type user account in addition to creating a group account? (And if so, what is the account's name?) Or is it merely adding a special system attribute to the group account created? If the latter, then the purpose of such accounts remains even less clear, as group accounts are by definition never logged into.