# groupmod

## 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:
    
           **-a** , **--append**
               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_
               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
               password policy.
    
           **-R** , **--root** _CHROOT_DIR_
               Apply changes in the _CHROOT_DIR_ directory and use the
               configuration files from the _CHROOT_DIR_ directory. Only
               absolute paths are supported.
    
           **-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.
    
           **-U** , **--users**
               A comma-separated list of usernames to add as members of the
               group.
    
               The default behavior (if the **-g** and **-U** options are not
               specified) is defined by the **USERGROUPS_ENAB** variable in
               /etc/login.defs.
    


## 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



           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: group id already in use
    
           _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
    


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