ADDUSER Linux Command

What is Linux adduser Command?

Explanation

adduser COMMAND:

The adduser command creates a new user or updates the default new user information. This command is very useful for Linux System Administrators to create user accounts on Linux with some specific properties and limitations. This command 'adduser' is similar to 'useradd' command which is also used for adding or creating user accounts, but it is a low-level utility. The adduser command is just a symbolic link to the 'useradd' command. When a new user is added then a corresponding entry is made in files /etc/passwd, /etc/group and /etc/shadow.

SYNTAX :


Usage: useradd [options] LOGIN useradd -D useradd -D [options]

OPTIONS:


-b, --base-dir BASE_DIR base directory for the home directory of the new account
-c, --comment COMMENT GECOS field of the new account
-d, --home-dir HOME_DIR home directory of the new account
-D, --defaults print or change default useradd configuration
-e, --expiredate EXPIRE_DATE expiration date of the new account
-f, --inactive INACTIVE password inactivity period of the new account
-g, --gid GROUP name or ID of the primary group of the new account
-G, --groups GROUPS list of supplementary groups of the new account
-h, --help display this help message and exit
-k, --skel SKEL_DIR use this alternative skeleton directory
-K, --key KEY=VALUE override /etc/login.defs defaults
-l, --no-log-init do not add the user to the lastlog and faillog databases
-m, --create-home create the user's home directory
-M, --no-create-home do not create the user's home directory
-N, --no-user-group do not create a group with the same name as the user
-o, --non-unique allow to create users with duplicate (non-unique) UID
-p, --password PASSWORD encrypted password of the new account
-r, --system create a system account
-R, --root CHROOT_DIR directory to chroot into
-s, --shell SHELL login shell of the new account
-u, --uid UID user ID of the new account
-U, --user-group create a group with the same name as the user
-Z, --selinux-user SEUSER use a specific SEUSER for the SELinux user mapping

When we run 'useradd' command in Linux terminal, it performs following major things:
  • It edits /etc/passwd, /etc/shadow, /etc/group and /etc/gshadow files for the newly created User account.
  • Creates and populate a home directory for the new user.
  • Sets permissions and ownerships to home directory.

EXAMPLE:


  1. To add/create a new user, all youve to follow the command 'useradd' or 'adduser' with 'username'. The 'username' is a user login name, that is used by user to login into the system.
    root@hioxsoftwares-HCL-Desktop:~# useradd test
    In this example,new user called 'test' is created.
  2. When we add a new user in Linux with 'useradd' command it gets created in locked state and to unlock that user account, we need to set a password for that account with 'passwd' command.
    root@hioxsoftwares-HCL-Desktop:~# passwd test Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully root@hioxsoftwares-HCL-Desktop:~# useradd test
    Once a new user created, its entry automatically added to the '/etc/passwd' file.
  3. The file is used to store users information and the entry should be.
    test:x:1001:1001::/home/test:

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