Bash script prints "Command Not Found" on empty lines

Question

Make sure your first line is:

#!/bin/bash

Enter your path to bash if it is not /bin/bash

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Try running:

dos2unix script.sh

That wil convert line endings, etc from Windows to unix format. i.e. it strips \r (CR) from line endings to change them from \r\n (CR+LF) to \n (LF).

More details about the dos2unix command (man page)

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Another way to tell if your file is in dos/Win format:

cat scriptname.sh | sed 's/\r/<CR>/'

The output will look something like this:

#!/bin/sh<CR>
<CR>
echo Hello World<CR>
<CR>

This will output the entire file text with <CR> displayed for each \r character in the file.

You can use bash -x scriptname.sh to trace it.

I also ran into a similar issue. The issue seems to be permissions. If you do an ls -l, you may be able to identify that your file may NOT have the execute bit turned on. This will NOT allow the script to execute. :)

As @artooro added in comment:

To fix that issue run chmod +x testscript.sh

This might be trivial and not related to the OP's question, but I often made this mistaken at the beginning when I was learning scripting

VAR_NAME = $(hostname)
echo "the hostname is ${VAR_NAME}"  

This will produce 'command not found' response. The correct way is to eliminate the spaces

VAR_NAME=$(hostname)

On Bash for Windows I've tried incorrectly to run

run_me.sh 

without ./ at the beginning and got the same error.

For people with Windows background the correct form looks redundant:

./run_me.sh