On Thursday 30 May 2019 12:07:13 pm Nathan Stratton Treadway wrote:
> On Thu, May 30, 2019 at 09:12:53 -0400, Gene Heskett wrote:
> > I found it, I think. In an effort to make my script immune to the
> > instant pwd of the launching shell, I had written an if statement:
> >
> > if [ $0 == "./backup.sh" ] || [ $0 == "${MYDIR}/backup.sh" ] || [ $0
> > == "backup.sh" ] ; then
>
> (If your goal is to let the script figure out it was invoked using the
> name "backup.sh", you might want to use the "basename" command
> instead.
>
> You can see an example in the script pointed to by both /bin/lesspipe
> /and bin/lessfile [under Debian], which contains:
> BASENAME=`basename $0`
> near the top and then checks if that equals "lessfile" at various
> points through the script, with the net effect that it behaves in
> "file" mode as long as the final component of the path used to invoke
> the script is "lessfile".
>
> In your case, probably you can just replace your if statement with
> if [ `basename $0` == "backup.sh" ]; then
>
> ...only be sure to test carefully afterwards to make sure it really
> does what you are actually intending....)
>
> > Now, is that 3rd "or" anything but trash code? I think it could
> > probably could be removed as I can't think of a launch condition
> > that would make it true.
>
> (It would trigger if backup.sh were found in your path and you just
> used the unprefixed name to run the script. But if you switch to the
> basename approach, the prefix part of your invocation won't matter.)
>
> Nathan
>
Sounds interesting Nathan. If I have to work on it again. I'll try to
keep that in mind. "basename $0" I assume sets $basename by stripping
off the leading path includeing the ./ ? That would rather simplify that
bit of logic.
Thanks Nathan.
Copyright 2019 by Maurice E. Heskett
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>
