groupmod - Modify a group
groupmod [-g gid [-o]] [-n group_name ] group
The groupmod command modifies the system account files to reflect the changes that are specified on the command line. The options which apply to
the groupmod command are
-g gid The numerical value of the group's ID. This value must be unique, unless the -o option is used. The value must be non-negative. Values
between 0 and 99 are typically reserved for system groups. Any files which the old group ID is the file group ID must have the file group
ID changed manually.
The name of the group will be changed from group to group_name.
/etc/group - group information
/etc/gshadow - secure group information