String equality in bash strings are equal when actually they are not

Question

#!/bin/bash
STR1="David20"
STR2="fbhfthtrh"

if [ "$STR1"="$STR2" ]; then

        echo "Both the strings are equal"
else
        echo "Strings are not equal"
fi

You need a space both sides of the equal sign: "$STR1" = "$STR2" — schrodingerscatcuriosity, Feb 20 '20 at 20:26
in bash use [[ ]], also use this site to validate your scripts. https://www.shellcheck.net/ — Jetchisel, Feb 20 '20 at 20:28
"$STR1"="$STR2" is equivalent to "$STR1=$STR2". You need to delimit with space. — ctrl-alt-delor, Feb 20 '20 at 20:31

score 5 · Answer 1 · answered Feb 20 '20 at 20:26

5

[ is a normal command (although a builtin) and the closing ] is just an argument to it. So is "$STR1"="$STR2" after the variables are expanded and quotes removed. The point is "$STR1"="$STR2" becomes one argument, and where there is just one argument before ] and it's a non-empty string, the result is true (exit status 0).

You want

[ "$STR1" = "$STR2" ]

Now there are three arguments before ] and the middle one (=) tells the command you want to compare strings.

answered Feb 20 '20 at 20:26

Kamil Maciorowski

21,864

Even with [[ (which isn't a normal command), [[ $a=$b ]] && echo yes always prints yes, for the same reason. – ilkkachu Feb 20 '20 at 22:05

String equality in bash strings are equal when actually they are not

1 Answers1