From LQWiki

The command useradd is used to create new users to your Linux system.

Using options to useradd you can specify a different placement for the users home directory for example. The option -D shows/sets the defaults for new users.

Contents 1 Quickstart 1.1 Command line options 1.2 Default Values 1.3 Specifying the Password 1.3.1 The Easy Way 1.3.2 The Not So Easy Way 1.4 See also

Quickstart

To add a user and set the password in a simple scenario (i.e. without home folders shared over different computers), open a ConSole and enter:

useradd -m username
passwd usernamd

Command line options

Specify the home directory:

-d home_dir

Create the home directory if it doesnt exit:

-m

Users Initial group:

-g initial_group

Add use to other groups:

-G group1,group2,etc

Select which shell they get:

-s shell

Default Values

To find out the default values that useradd will use, run:

$ useradd -D

Specifying the Password

The Easy Way

Use the passwd command as root. By default passwd prompts for and changes the password of the user running it, but root can specify a different username as a command line argument and change that person's password.

Example of command to change the password for user Bob:

# passwd bob

The Not So Easy Way

You can specify the password for the user using the -p option. The password must be specified with the output of the crypt function.

Command line access to crypt is somewhat rare. The following C code generates an executable that will encrypt a password for you:

#include <stdio.h>
#include <unistd.h>
// compile with:  g++ crypt.c -o crypt -lcrypt

int main(int argc, char** argv)
{
  if( argc != 2 ) {
    printf("usage: %s key-to-encrypt", argv[0]);
    return 1;
  }

  printf("%s\n", crypt(argv[1], "01"));

  return 0;
}

See also

• user-commands
• userdel
• usermod
• groupadd
• passwd