Cygwin $0 not working as exptected

Question

I have an odd behavior of $0 under cygwin.

In my script, I do echo "$0", and get as output -bash instead of the pathname. However, if I do realpath $0, i get the actual path. Why is that, and do other people encounter this, too?

I am trying to source the script, does this change things?

Answer 1

Yes, sourcing is the reason. Sourcing does not start a different process, so things like $0 will continue to have their values when the script is being sourced.

Here is a script myname:

#!/bin/bash
echo "$0"

Here is the sourcing:

$ source myname
-bash

And here is running the script:

$ ./myname
./myname

There you are!

Update: This is not cygwin specific. All shells should behave this way, by design.