groupmod — Modify a group
Summary :
The groupmod command modifies the system account files to reflect the
changes that are specified on the command line.
Example:
# groupmod -g 600 mygrp — Change the mygrp Group ID to 600.
# groupmod -n mygrp1 mygrp — Change the mygrp name to mygrp1.
Group informations are stored in /etc/group files.
Read: man groupmod