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I have following bash script:

#!/bin/bash
  
echo "Enter your name: "
read name

if [ ${name}=="sam" ]  
then
        echo "Hi Sam!"
else
        echo "Who the hell are you?"
fi

I want it to display "Who the hell are you?" if the entered name is not "sam". But it displays "Hi Sam!" even when I enter random string.

What is the problem here?

4
5

Please read bash tutorials and manual on using conditional expressions, e.g. [ ] and test.

In short:

  1. There's no need to use ==, as = is enough.
  2. You must put spaces before and after = because otherwise instead of comparing you're assigning the right part of the expression to the left one.
  3. Do quote your variables

The net result:

if [ "${name}" = "sam" ]
4
  • It's probably worth mentioning that it is incorrect to use == with [, it will work in some shells but == is a bashism and should be used only with [[ tests. Additionally there is no need to use ${name}, $name will suffice.
    – jesse_b
    Sep 17 '20 at 15:48
  • 1
    No, if [ "${name}"=="sam" ]; then ... doesn't assign anything to anything. It just succeeds and takes the then branch, no matter what value $name has.
    – user414777
    Sep 17 '20 at 16:06
  • Actually it does: a=="1";echo $a => =1 Sep 17 '20 at 17:03
  • Not in [ a=="1" ]
    – user414777
    Sep 17 '20 at 17:22

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