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21.2.2. Adding a User

To add a user to the system:
  1. Issue the useradd command to create a locked user account:
    useradd <username> 
  2. Unlock the account by issuing the passwd command to assign a password and set password aging guidelines:
    passwd <username> 
Command line options for useradd are detailed in Table 21.1, “ useradd Command Line Options”.
Option Description
-c '<comment>' <comment> can be replaced with any string. This option is generally used to specify the full name of a user.
-d <home-dir> Home directory to be used instead of default /home/<username>/
-e <date> Date for the account to be disabled in the format YYYY-MM-DD
-f <days> Number of days after the password expires until the account is disabled. If 0 is specified, the account is disabled immediately after the password expires. If -1 is specified, the account is not be disabled after the password expires.
-g <group-name> Group name or group number for the user's default group. The group must exist prior to being specified here.
-G <group-list> List of additional (other than default) group names or group numbers, separated by commas, of which the user is a member. The groups must exist prior to being specified here.
-m Create the home directory if it does not exist.
-M Do not create the home directory.
-n Do not create a user private group for the user.
-r Create a system account with a UID less than 500 and without a home directory
-p <password> The password encrypted with crypt
-s User's login shell, which defaults to /bin/bash
-u <uid> User ID for the user, which must be unique and greater than 499
Table 21.1.  useradd Command Line Options