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This short article is about creating a Bash script that automates adding users and assigning passwords for Linux operating system. In Linux operating system, useradd command is used to add new users and provide passwords to them.

Bash script useradd command

A simple utility for adding users is useradd. Debian administrators should usually use adduser instead.

Invoking the useradd command without the -D option creates a new user account based on the values ​​entered on the command line and the system defaults. The useradd command updates system files and may perform other tasks depending on the command line options.

Also, create a home directory for the new user and copy the initial files.

Bash script for adding users

In Linux operating system, we need to be the root user to add new users to the system. Therefore, in the script, we first need to verify whether the user running the script is the root user.

After that, we can get the input username and password from the user and then run useraddthe command. Let's take a look at the following script.

Bash script:

#!/bin/bash

if [ $(id -u) -eq 0 ]; then
    read -p "Enter your  username : " user_name
    read -s -p "Enter your password : " pass
    egrep "^$user_name" /etc/passwd >/dev/null
    if [ $? -eq 0 ]; then
        echo "$user_name exists!"
        exit 1
    else
        epass=$(perl -e 'print crypt($ARGV[0], "pass")' $pass)
        useradd -m -p "$epass" "$user_name"
        [ $? -eq 0 ] && echo "Successfully added User!" || echo "Sorry! User not added"
    fi
else
    echo "Sorry! You are not authorized to add users."
    exit 2
fi

After reading the username and password from the user, we first egrepsearch if the user with the given username already exists using the command. If the user entry is found in the /etc/passwd file, it means that the user already exists.

Otherwise, we will encrypt the password using perl command. The perl command will display the screen with the encrypted password.

The function in Perl crypt()uses a one-way encryption algorithm. Once the password is encrypted, it cannot be decrypted. Get the user's password string, encrypt it with salt, and then display it on the computer screen.

After running the useradd command, we will use the $? value and display an appropriate message to the user.

Output: