$ Linux Command

Permissions

groupmems

Manage members of a user's own group.

groupusermembershipshadowpermissions

Additional Notes

groupmems allows a user to manage the membership of their own primary group without requiring root privileges. It is part of the shadow password suite and provides a controlled way to add or remove users from a group, as long as the user running it is the group owner.

The command is typically restricted to root and the group owner, as defined in the /etc/gshadow file. The group owner entry in the last field of /etc/gshadow determines who is allowed to manage membership. This is useful for delegating group administration to non-root users.

Syntax

groupmems [options]

Parameters

  • options: Flags that change how groupmems behaves.
  • target: Optional file, device, interface, user, service, or command target when the command supports one.

Common Options

  • -g group, --group group: Specify the group to manage. The group must have an owner set in /etc/gshadow.
  • -a user, --add user: Add a user to the group.
  • -d user, --delete user: Remove a user from the group.
  • -p, --purge: Remove all members from the group.
  • -l, --list: List the members of the group.
  • -R, --root directory: Apply changes in a different root directory (for chroot environments).

Examples

sudo groupmems -g developers -a alice

Add alice to the developers group.

sudo groupmems -g developers -d bob

Remove bob from the developers group.

groupmems -g developers -l

List all members of the developers group.

sudo groupmems -g oldgroup -p

Remove all members from oldgroup.

Practical Notes

  • The group must have an owner defined in the /etc/gshadow file (the last field). Without an owner, only root can manage membership.
  • groupmems modifies /etc/group and /etc/gshadow directly; users must log out and back in for the group membership change to take effect.
  • The newgrp or sg commands can be used to switch the active group to a new one after membership changes.
  • For most group management tasks, gpasswd and usermod -aG are more commonly used.
  • groupmems is rarely used on modern systems compared to usermod and gpasswd.