I need to manually edit /etc/shadow to change the root password inside of a virtual machine image.

Is there a command-line tool that takes a password and generates an /etc/shadow compatible password hash on standard out?

Best Answer

You can use the following commands for the same

Method 1 (md5, sha256, sha512)

openssl passwd -6 -salt xyz  yourpass

Note: passing -1 will generate an MD5 password, -5 a SHA256 and -6 SHA512 (recommended)

Method 2 (md5, sha256, sha512)

mkpasswd --method=SHA-512 --stdin

The option --method accepts md5 , sha-256 and sha-512

Method 3 (des, md5, sha256, sha512)

As @tink suggested, we can update the password using chpasswd using.

echo "username:password" | chpasswd

Or you can use the encrypted password with chpasswd . We'll first create it using this

perl -e 'print crypt("YourPasswd", "salt", "sha512"),"\n"'

Then later you can use the generated password to update /etc/shadow .

echo "username:encryptedPassWd" | chpasswd -e

The encrypted password we can also use to create a new user with this password, for example.

useradd -p 'encryptedPassWd'  username