groupmod(8) — Linux manual page


GROUPMOD(8)              System Management Commands              GROUPMOD(8)

NAME         top

       groupmod - modify a group definition on the system

SYNOPSIS         top

       groupmod [options] GROUP

DESCRIPTION         top

       The groupmod command modifies the definition of the specified GROUP
       by modifying the appropriate entry in the group database.

OPTIONS         top

       The options which apply to the groupmod command are:

       -a, --append GID
           If group members are specified with -U, append them to the
           existing member list, rather than replacing it.

       -g, --gid GID
           The group ID of the given GROUP will be changed to GID.

           The value of GID must be a non-negative decimal integer. This
           value must be unique, unless the -o option is used.

           Users who use the group as primary group will be updated to keep
           the group as their primary group.

           Any files that have the old group ID and must continue to belong
           to GROUP, must have their group ID changed manually.

           No checks will be performed with regard to the GID_MIN, GID_MAX,
           SYS_GID_MIN, or SYS_GID_MAX from /etc/login.defs.

       -h, --help
           Display help message and exit.

       -n, --new-name NEW_GROUP
           The name of the group will be changed from GROUP to NEW_GROUP

       -o, --non-unique
           When used with the -g option, allow to change the group GID to a
           non-unique value.

       -p, --password PASSWORD
           The encrypted password, as returned by crypt(3).

           Note: This option is not recommended because the password (or
           encrypted password) will be visible by users listing the

           You should make sure the password respects the system's password

       -R, --root CHROOT_DIR
           Apply changes in the CHROOT_DIR directory and use the
           configuration files from the CHROOT_DIR directory.

       -P, --prefix PREFIX_DIR
           Apply changes in the PREFIX_DIR directory and use the
           configuration files from the PREFIX_DIR directory. This option
           does not chroot and is intended for preparing a cross-compilation
           target. Some limitations: NIS and LDAP users/groups are not
           verified. PAM authentication is using the host files. No SELINUX

       -U, --users
           A list of usernames to add as members of the group.

           The default behavior (if the -g, -N, and -U options are not
           specified) is defined by the USERGROUPS_ENAB variable in


       The following configuration variables in /etc/login.defs change the
       behavior of this tool:

       MAX_MEMBERS_PER_GROUP (number)
           Maximum members per group entry. When the maximum is reached, a
           new group entry (line) is started in /etc/group (with the same
           name, same password, and same GID).

           The default value is 0, meaning that there are no limits in the
           number of members in a group.

           This feature (split group) permits to limit the length of lines
           in the group file. This is useful to make sure that lines for NIS
           groups are not larger than 1024 characters.

           If you need to enforce such limit, you can use 25.

           Note: split groups may not be supported by all tools (even in the
           Shadow toolsuite). You should not use this variable unless you
           really need it.

FILES         top

           Group account information.

           Secure group account information.

           Shadow password suite configuration.

           User account information.

EXIT VALUES         top

       The groupmod command exits with the following values:

           E_SUCCESS: success

           E_USAGE: invalid command syntax

           E_BAD_ARG: invalid argument to option

           E_GID_IN_USE: specified group doesn't exist

           E_NOTFOUND: specified group doesn't exist

           E_NAME_IN_USE: group name already in use

           E_GRP_UPDATE: can't update group file

           E_CLEANUP_SERVICE: can't setup cleanup service

           E_PAM_USERNAME: can't determine your username for use with pam

           E_PAM_ERROR: pam returned an error, see syslog facility id
           groupmod for the PAM error message

SEE ALSO         top

       chfn(1), chsh(1), passwd(1), gpasswd(8), groupadd(8), groupdel(8),
       login.defs(5), useradd(8), userdel(8), usermod(8).

COLOPHON         top

       This page is part of the shadow-utils (utilities for managing
       accounts and shadow password files) project.  Information about the
       project can be found at ⟨⟩.  If
       you have a bug report for this manual page, send it to  This page was obtained
       from the project's upstream Git repository
       ⟨⟩ on 2020-09-18.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-08-28.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to

shadow-utils 4.8.1               09/18/2020                      GROUPMOD(8)

Pages that refer to this page: gpasswd(1)groupadd(8)groupdel(8)grpck(8)useradd(8)userdel(8)usermod(8)