Say you have a user account on server1 and want to create user on server2 with the same credentials, but you do not actually know the password of that user.

on server1, you can see the encoded version of the password with:\ > grep username /etc/shadow | awk -F: {'print \$2'}

and then

create user on the destination server (server2).\ paste the encrypted password in /etc/shadow, on the destination server.