groupmod

Updated

September 4, 2026

Overview

groupmod modifies an existing group: rename it, change its GID, or adjust related attributes depending on the implementation. Membership lists are often managed via usermod/gpasswd rather than groupmod.

Requires root privileges.

Syntax

groupmod [options] GROUP

Common Options

Option Description
-n NEWNAME, --new-name Rename group
-g GID, --gid Change GID
-o, --non-unique Allow non-unique GID
-p PASSWORD Set encrypted password (rare; prefer gpasswd)
-R CHROOT Chroot directory
-P PREFIX Prefix directory

Examples with Explanations

Rename a group

getent group devs
sudo groupmod -n developers devs
getent group developers

Change GID

getent group developers
sudo groupmod -g 1200 developers

Warning: files owned by the old numeric GID are not rewritten automatically. Plan a find/chgrp migration.

Migrate file ownership after GID change

old=1004
new=1200
sudo find /srv/data -group $old -exec chgrp $new {} +

Scope carefully; avoid full-filesystem finds without need.

Non-unique GID (rare)

sudo groupmod -o -g 1000 shared

Usually a bad idea — collisions confuse tools.

Verify

getent group developers
grep developers /etc/group /etc/gshadow

Notes / Pitfalls

  • Renaming may break configs that hard-code the old group name (sudoers, ACLs, unit files).
  • Changing GID without file migration leaves orphaned ownership.
  • Directory services: local groupmod won’t change LDAP groups.
  • Running processes keep old credentials until re-login / re-spawn.
  • Avoid editing /etc/group by hand when groupmod exists.

2026-relevant notes

  • Infrastructure as code should declare desired group names/GIDs immutably; avoid frequent renames.
  • Container images: GID consistency across images matters for shared volumes — set explicitly.
  • Prefer supplementary group membership management with usermod -aG over renaming shared groups.

Additional Resources

  • man groupmod