System administration command. Create new user accounts or update default account information. Unless invoked with the -D option, user must be given. useradd will create new entries in system files. Home directories and initial files may also be created as needed.
Specify base dir for home directories. The default is /home.
Home directory. The default is to use user as the directory name under the home directory specified with the -D option.
Set or display defaults. If options are specified, set them. If no options are specified, display current defaults. The options are:
Home directory prefix to be used in creating home directories. If the -d option is not used when creating an account, the user name is appended to dir.
Expire date. Requires the use of shadow passwords.
Number of days after a password expires to disable an account. Requires the use of shadow passwords.
Initial group name or ID number.
Default login shell.
Account expiration date. Use the format MM/DD/YYYY. Two-digit year fields are also accepted. The value is stored as the number of days since January 1, 1970. This option requires the use of shadow passwords.
Permanently disable account this many days after the password ...