Setting Passwords for User Accounts in Linux

The useradd command in Linux is used to create new user accounts. One of the important options available for this command is -p or --password PASSWORD, which allows setting passwords for the newly created user accounts.

Here are several examples of using useradd with the -p option:

Example 1: Create a new user john and set the password immediately.

$ sudo useradd -p 'password123' john
        

This command creates a user account named john with the password set to password123.

To verify if the user was successfully created, you can use:

$ grep john /etc/passwd
        

If john is listed in the output, the user account was created.

Example 2: Create a user alice and set her password using an encrypted password string.

$ sudo useradd -p '$6$3.4Fajk$Gy5dZf4Bkp1l1puM4vWb2LWf1xCM72BY1.sE6D0B/7OIGTb9NArS.eUvw0B2m3.u6Onz5sBwFtD/ghJvDAg9u/' alice
        

In this command, the password is set using an encrypted password string, ensuring stronger security.

Example 3: Create a user smith and set the password using an MD5 hash.

$ sudo useradd -p '$1$av7iwD7b$Asnkj234.DXG0RlsN8h7Y1' smith
        

This command demonstrates setting a password using an MD5 hash for the user smith.

Example 4: Set password for an existing user jane using the passwd command after creation.

$ sudo useradd jane
$ sudo passwd jane
        

This sequence first creates the user jane and then prompts to set a password interactively.

Example 5: Create a user guest and set an empty password.

$ sudo useradd -p '' guest
        

Setting an empty password can be useful in some scenarios but is generally discouraged for security reasons.

These examples illustrate different ways to use the useradd command with the -p option to set passwords for user accounts in Linux. Each method offers flexibility depending on the security requirements and administrative needs of the system.