How to Generate Random Password in Linux

Often system administrators need to generate random strong passwords for their users’ authentication credentials, or for other purposes. In this article, we will learn about a few commands you can use to generate random password in Linux. We will also learn how to create encrypted salt-based passwords in Linux.

How to Generate Random Password in Linux

There are plenty of random string generator commands in Linux. We will look at some of them.

1. Pwgen

Pwgen is one of the simplest tools to generate random password in Linux. You can easily install it with the following command.

# Ubuntu/Debian
$ sudo apt-get install pwgen

# RHEL/CentOS/SUSE/Fedora
$ yum install pwgen

Once it is installed, you can generate a random password of specific length , using the following command.

$ pwgen password_length number_of_passwords

In the above command, the first argument is the password length while the second argument is the number of passwords.

Here is the command to generate a random password of length 10 characters using pwgen.

$ pwgen 10 1
hmehierw48
$ pwgen 10 1
8cyr847c48

As you can see above, pwgen generates a new random password every time you run it.

If you omit the last argument, pwgen will generate a set of random passwords. Here is a command to generate multiple random passwords of length 10.

$ pwgen 10
erheuhieh9
94h849hcrc
cr49ch94hc
xr4ucm40c0
rj40c4r0mr
...

2. Using makepasswd

Similarly, you can also use makepasswd command to generate random passwords of specific length. You can install it with the following command.

# Ubuntu/Debian
$ sudo apt-get install makepasswd

# RHEL/CentOS/Fedora/SUSE
$ yum install makepasswd

Once it is installed, you can generate random passwords using the makepasswd command

$ makepasswd
erh9r8404r

By default, makepasswd generates a random password of length 10.

If you want to generate password of another specific length, you can use the –char option. Here is the command to generate password of length 20.

$ makepasswd --char 20

If you need to generate more than 1 password at a time, you need to specify the number of password to be generated using –count option. Here is the command to generate 5 random passwords of length 10 each.

$ makepassword --char 10 --count 5

3. Using mkpasswd

Mkpasswd is a handy command to encrypt existing passwords using salt strings. Salt is a basically an additional string used by program to generate encrypted password, to prevent outsiders from simply brute forcing their way to get your password, using the same tool that you use to generate passwords.

If you want to encrypt passwords based on specific string, you can use mkpasswd tool for that purpose.

# Ubuntu/Debian
$ sudo apt-get install mkpasswd

# RHEL/CentOS/SUSE/Fedora
$ yum install mkpasswd

Here is a simple command to encrypt password ‘linux’ using mkpasswd command.

$ mkpasswd linux
94rh498h45
$ mkpasswd linux
e9c48h849c

In the above examples, mkpasswd uses random salt string every time. If you want to specify salt string you can do so with -s option. Here is an example to use tt as salt string

$ mkpasswd linux -s tt
tt09yrnc498n
$ mkpasswd linux -s tt
tt09yrnc498n

As you can see above, in this case, mkpasswd generates the same encrypted password every time, for the same input, because we have specified the salt string.

In this article, we have learnt several different tools to generate random passwords in Linux. You can run these commands on terminal, or even add them to shell script to automate password generation.

How to Generate Random Password in Linux