$ openssl passwd -salt Xx -crypt 1234
Xx7LFoJpR7vp.

#!/bin/bash
# script to change a password
username() {
while :
do
   read -p "please enter a username: " user
   ln=$(grep "^$user" usernames)
   pass=${ln#* }
   salt=${pass:0:2}
   if [ "$(openssl passwd -salt ${salt:-XX} | sed 's/\r//')" = "$pass" ]
   then
      echo "Welcome $user"
      break
   else
      echo "Password incorrect - please retry"
      echo
   fi
done
}
change1 () {
    new=$(while ! openssl passwd ; do echo "try again
">&2; done)
    sed -i "s:^${user} .*:${user} ${new}:" usernames
}
username
change1