Linux Scripting – Change Password Programmatically

linuxpasswordraspbianscripting

In the current version of Raspian, I know it is possible to change the password of the current logged in user from the command line like so:

sudo passwd

which will then prompt the user to enter a new password twice. This will produce output like so:

Changing password for pi.
(current) UNIX password:
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

I was wondering if there is a possible way to change a password programmatically, like from a shell script.

I'm trying to make a configuration script to deploy on my Raspberry Pis and I don't want to manually have to type in new passwords for them.

Best Answer

You're looking for the chpasswd command. You'd do something like this:

echo 'pi:newpassword' | chpasswd # change user pi password to newpassword

Note that it needs to be run as root, at least with the default PAM configuration. But presumably run as root isn't a problem for a system deployment script.

Also, you can do multiple users at once by feeding it multiple lines of input.

Related Solutions

Centos – Policy in /etc/pam.d/password-auth is not being enforced

You have to check your /etc/pam.d/passwd file if it includes /etc/pam.d/password-auth or /etc/pam.d/system-auth and to make required changed in file which is included.

In short:
An application that uses PAM can have a configuration file bearing its name in /etc/pam.d/. If a file exists, the rules in that file are processed whenever the application calls a PAM authentication function.

Files like /etc/pam.d/system-auth and to a larger extent /etc/pam.d/password-auth are somewhat distribution-specific. Since no applications identify themselves as "system-auth" or "password-auth", these files are actually never called on their own. Instead, the contents of these files are pulled into other PAM configuration files with the "include" directive. That way, common settings for multiple applications can be stored in a single file.

Linux – Password change Script

You can save the generated password in a variable, and write it two files:

One file in clear
One file hashed

For example:

# initialize (truncate) output files
> clear.txt
> hashed.txt

cut -d: -f1 pw.txt | while read -r user; do        
    # generate a hash from a random number
    hash=$(openssl passwd $RANDOM)

    # use the first 8 letters of the hash as the password
    pass=${hash:0:8}

    # write password in clear formats to one file, and hashed in another
    echo "$user:$pass" >> clear.txt
    echo "$user:$(openssl passwd $pass)" >> hashed.txt
done

Best Answer

Related Solutions

Centos – Policy in /etc/pam.d/password-auth is not being enforced

Linux – Password change Script

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