groupmod(1M)

NAME

groupmod — modify a group on the system

SYNOPSIS

groupmod [-g gid [-o] ] [-n name] group

DESCRIPTION

The groupmod command modifies a group on the system by altering the appropriate entry in the /etc/group file.

The groupmod command must be used with the group argument, which is the name of the group to be modified.

Options

The groupmod command may be used with the following options:

-g gid: Change the value of the group ID to gid. gid must be a non-negative decimal integer less than MAXUID as defined in the <param.h> header file.
-o: Allow the gid to be non-unique (i.e., a duplicate).
-n name: Change the name of the group to name. name consists of a string of printable characters that may not include a colon (:) or newline (\n).

NETWORKING FEATURES

This command is aware of NIS user entries. Only local groups may be modified with groupmod. Attempts to modify an NIS group will result in an error. NIS groups must be administered from the NIS server. If groupmod is used on a system where NIS is installed, it may fail with the error

group x does not exist

(return value 6) if the group specified is an NIS group (see group(4)). However, NIS groups are checked when verifying uniqueness of the new gid or new group name, which may result in the above error, or the error

GID # is not unique 

(return value 4).

RETURN VALUES

groupmod exits with one of the following values:

0: No error.
2: Invalid command syntax.
3: Invalid argument supplied to an option.
4: gid is not unique (when -o is not used).
6: group does not exist.
9: group is not unique.
10: Cannot modify the /etc/group file.
11: /etc/passwd file or /etc/ptmp file busy. Another command may be modifying the /etc/passwd file.
12: Unable to open /etc/ptmp file or the /etc/passwd file is non-existent.

EXAMPLES

Change the group ID of the group project2 to 111 in the file /etc/group if the group project2 exists. This is done even if the group ID 111 is already in use.

groupmod -g 111 -o project2 

Change the name of project2 to project22 in the file /etc/group if the group project22 does not already exist.

groupmod -n project22 project2 

WARNINGS

As many users may try to write the /etc/passwd file simultaneously, a passwd locking mechanism was deviced. If this locking fails after subsequent retrying, groupmod terminates.

FILES

/etc/group 
/etc/ptmp 

STANDARDS CONFORMANCE

groupmod: SVID3