Need some help with bash

Off-topic
1

Need some help interpreting the result of this command. Results don’t seem to be intuitive.

  1. I ran the following and it evaluates the “if” block:

root@kali:/tmp# if [[ 0 ]]; then echo “return true”; else echo “return false”; fi

return true

  1. Now, I have two files with same content, test1.txt and test2.txt

root@kali:/tmp# echo test > test1.txt
root@kali:/tmp# cp test1.txt test2.txt

  1. I would expect the following to run the “if” block, but it executes the “else” block. I am not sure why, especially in step 1 the same thing executes the “if” block.

root@kali:/tmp# if [[ $(diff test1.txt test2.txt) ]]; then echo “return true”; else echo “return false”; fi

return false

I am missing something, but not sure what. Thanks in advance!

2

If two files are the same, diff provides nothing, not even 0, to stdout. Perhaps you can use md5sum with your If-then-else-fi.

3

Thank you so much - That helps. Figured it now!