On Wed, 27 Feb 2008, Mike Miller wrote:

> There are four ways that the script could have been executed:
>
> (1) absolute path
>     example:  /usr/local/bin/script.bash
>
> (2) relative path
>     example:  ../../../local/bin/script.bash
>     example:  ./local/bin/script.bash
>     example:  local/bin/script.bash
>
> (3) in search path ($PATH)
>     example:  script.bash
>
> (4) as above but using globbing
>     example:  local/bin/scri*

It is also possible to have used ${HOME} or ~ in the file specification, 
or even some other variable like ${SCRIPT} or ${SOME_DIR}.  I think those 
end up working like "4" and the variable or ~ is expanded to a string that 
then becomes $0.

Mike