Until user input matches variable do

Question

Okay, so I'm trying to create a username/password login script of sorts. (may not be the most secure idea I'm still working on it) ;)

My script will load variables to compare to from file like this. (right now I'm just working on password portion)

./path/to/variables.conf

This file will contain a variable called

PASS=SOME_VALUE 

I plan to use read to obtain the variable that will be compared

read -p "Enter your password:" CPASS; 

Now the part I'm missing (how I envision it working)

while "$CPASS" doesn't match "$PASS" do 
read -p "Wrong password, try again:" CPASS;

Thank you & any help is appreciated.

Answer 1

This should do it. You just need [ ] braces and the != operator to compare strings in bash:

PASS=SOME_VALUE

read -p "Enter your password:" CPASS

while [ "$CPASS" != "$PASS" ]; do 
    read -p "Wrong password, try again:" CPASS
done

Also note it would be highly advisable to pass the -s parameter to read, so that the entered password is not echoed back to the user. From the read section of man bash:

          -s     Silent  mode.  If input is coming from a terminal, char-
                 acters are not echoed.

Note though that there will also be no newline echoed back to the user when the user hits ENTER, so you'll have to manually insert a newline after every read so that lines are properly formatted. So you should probably replace your read statements with something like this:

read -s -p "Enter your password:" CPASS
echo