Bashscript making a variable equal a command. error command not found

Question

Hi i keep getting the error

./imagehash.sh: line 2: =: command not found

When i know that i set the $CMD variable correctly (i tried the command outside the bash script and it worked just fine)

here's my bash script

#!/bin/bash
 $CMD='md5sum ../Desktop/cases/CourseworkCase/Evidence/image.dd'
 echo $CMD

UPDATE

fixed the bash so theres no spaces in the $CMD variable and put '' around it but now i'm getting the error file no such file or directory i looked at the path and copied it letter for letter and its correct.

what am i doing wrong here?

Solution

Working example

#!/bin/bash
CMD="$(md5sum ../Desktop/cases/CourseworkCase/Evidence/image.dd)"
echo $CMD

Explanation

1. To assign a variable never put a $ sign before nor spaces around the equal sign. The variable assignment in bash is like this:

   MYVAR="CONTENT"
   

2. To create a variable with the output of a command you may use $(command). This will execute command and return its output.

3. The output of md5sum will be like this:

   f110abe5b3cfd324c2e5128eb4733879 image.dd
   

   If do you want to isolate the md5 sum of the file name, you can use one of these lines instead:

   CMD="$(md5sum ../Desktop/cases/CourseworkCase/Evidence/image.dd | cut -d ' ' -f 1)"
   CMD=($(md5sum ../Desktop/cases/CourseworkCase/Evidence/image.dd))
   

Comments

[Nam Nguyen]

also please do not forget to quote $CMD. You can use this tool to check your script: shellcheck.net

[Nam Nguyen]

@helio: github.com/koalaman/shellcheck/wiki/SC2086