-f

This option causes the command to simply exit with success status if the specified group already exists. When used with -g, andthe specified GID already exists, another (unique) GID is chosen (i.e. -g is turned off).

-g

The numerical value of the group's ID. This value must be unique, unless the -o option is used. The value must be non-negative.The default is to use the smallest ID value greater than or equal to GID_MIN and greater than every other group.See also the -r option and the GID_MAX description.

-h

Display help message and exit.

-K

Overrides /etc/login.defs defaults (GID_MIN, GID_MAX and others). Multiple -K options can be specified.Example: -K GID_MIN=100 -K GID_MAX=499Note: -K GID_MIN=10,GID_MAX=499 doesn't work yet.

-o

This option permits to add a group with a non-unique GID.

-p

The encrypted password, as returned by crypt(3). The default is to disable the password.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

Create a system group.The numeric identifiers of new system groups are chosen in the SYS_GID_MIN-SYS_GID_MAX range, defined in login.defs, instead ofGID_MIN-GID_MAX.

-R

Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory.CONFIGURATIONThe following configuration variables in /etc/login.defs change the behavior of this tool:GID_MAX (number), GID_MIN (number)Range of group IDs used for the creation of regular groups by useradd, groupadd, or newusers.The default value for GID_MIN (resp. GID_MAX) is 1000 (resp. 60000).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 samename, 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 NISgroups 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 youreally need it.SYS_GID_MAX (number), SYS_GID_MIN (number)Range of group IDs used for the creation of system groups by useradd, groupadd, or newusers.The default value for SYS_GID_MIN (resp. SYS_GID_MAX) is 101 (resp. GID_MIN-1).FILES/etc/groupGroup account information./etc/gshadowSecure group account information./etc/login.defsShadow password suite configuration.CAVEATSIt is usually recommended to only use groupnames that begin with a lower case letter or an underscore, followed by lower caseletters, digits, underscores, or dashes. They can end with a dollar sign. In regular expression terms: [a-z_][a-z0-9_-]*[$]?On Debian, the only constraints are that groupnames must neither start with a dash ('-') nor plus ('+') nor tilde ('~') nor contain acolon (':'), a comma (','), or a whitespace (space:' ', end of line: '\n', tabulation: '\t', etc.).Groupnames may only be up to 32 characters long.You may not add a NIS or LDAP group. This must be performed on the corresponding server.If the groupname already exists in an external group database such as NIS or LDAP, groupadd will deny the group creation request.EXIT VALUESThe groupadd command exits with the following values:0success2invalid command syntax3invalid argument to option4GID not unique (when -o not used)9group name not unique10can't update group file