GROUPMOD(8)               (02/07/2020)                GROUPMOD(8)

     NAME
          groupmod - modify a group definition on the system

     SYNOPSIS
          groupmod [options] GROUP

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

     OPTIONS
          The options which apply to the groupmod command are:

          -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 name.

          -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 processes.

              You should make sure the password respects the system's

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              password policy.

          -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 support.

     CONFIGURATION
          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
          /etc/group
              Group account information.

          /etc/gshadow
              Secure group account information.

          /etc/login.defs
              Shadow password suite configuration.

          /etc/passwd
              User account information.

     EXIT VALUES

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          The groupmod command exits with the following values:

          0
              E_SUCCESS: success

          2
              E_USAGE: invalid command syntax

          3
              E_BAD_ARG: invalid argument to option

          4
              E_GID_IN_USE: specified group doesn't exist

          6
              E_NOTFOUND: specified group doesn't exist

          9
              E_NAME_IN_USE: group name already in use

          10
              E_GRP_UPDATE: can't update group file

          11
              E_CLEANUP_SERVICE: can't setup cleanup service

          12
              E_PAM_USERNAME: can't determine your username for use
              with pam

          13
              E_PAM_ERROR: pam returned an error, see syslog facility
              id groupmod for the PAM error message

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

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