Shell script comparing strings

Question

Here's part of a shellscript I'm writing checking passwords stored in a file (along with names):

VALID_PASSWORD=`grep "Karl Marks" hiddenpasswords.txt|cut -f2 -d,`
echo $VALID_PASSWORD
echo enter password1
echo "Please enter the password"
read PASSWORD
if test "$PASSWORD" = "$VALID_PASSWORD"
then
echo "you have access"
else
echo "access denied"
fi

The grep part takes the correct password from the file, however "access denied" is always run no matter what I type in.

Chances are that there is a space after VALID_PASSWORD. Try saying echo "${VALID_PASSWORD}." — devnull
– devnull, Commented Jan 24, 2014 at 16:15
What happens when you run the script with sh -x? Does that tell you what is going wrong? Have you tried echoing echo "[$VALID_PASSWORD]" with the square brackets to indicate the limits of the variable? Have you tried echo "[$PASSWORD]" to see what that yields? — Jonathan Leffler
– Jonathan Leffler, Commented Jan 24, 2014 at 16:16
If you don't want the entered password to be visible as the user types it, use read -s PASSWORD (assuming you use bash) — glenn jackman
– glenn jackman, Commented Jan 24, 2014 at 16:19

anubhava · Accepted Answer · 2014-01-24 16:17:19Z

1

The grep part takes the correct password from the file, however "access denied" is always run no matter what I type in.

It could be due to presence of whitespaces in your $VALID_PASSWORD.

Try changing first line to:

VALID_PASSWORD=$(awk -F '[, ]+' '/Karl Marks/ {print $2}' hiddenpasswords.txt)

TIP: Check content of both variables using cat -vte

echo "VALID_PASSWORD" | cat -vte
echo "PASSWORD" | cat -vte

answered Jan 24, 2014 at 16:17

anubhava

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5 Comments

glenn jackman Over a year ago

+1 good advice. another method to view the contents of the variables: od -c <<<"$VALID_PASSWORD"

anubhava Over a year ago

Yes agreed, od -c is even more detailed info.

user3232310 Over a year ago

When I add the echo "VALID_PASSWORD" | cat -vte echo "PASSWORD" | cat -vte

user3232310 Over a year ago

When I add the echo "VALID_PASSWORD |cat -vte

anubhava Over a year ago

Not getting your comments.

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