Re: [MacPerl] [OFF-TOPIC] shebang line (was: UNIX "system"command)

[Juergen Christoffel <Mac.Christoffel@gmd.de>]

This [OFF-TOPIC] marker really is a clever idea. So, while we are
officially off-topic here, allow me to add my two cents worth of non-Mac
information too ;-)

At 18:34 +0200 30.07.97, Terje Bless wrote:

>The shebang line isn't interpreted by perl. It's there to allow a different
>interpreter for the script then the current shell

It isn't interpreted by perl, that's correct, but no, it doesn't have to do
with the "current shell"

>Nothing you do to the perl binary will let it catch the shebang line before
>the shell. If "/usr/bin/perl" doesn't exist your shell will cry foul before
>"/opt/gnu/perl" ever sees it.

... the "#!..." is interpreted by the Unix kernel itself to look up the
interpreter for the executable file. The shell just forks and then does an
execve system call for files with the x-bit set and that execve looks up
the interpreter to use. A long, long time ago the two bytes at the front of
executables where actual machine instructions for the PDP but now are
mostly used as magic for commands like "file".

>PS. Wouldn't Concert/Rhapsody be a great development platform for Perl? :-)

Yes it would. I fondly remember A/UX which Apple killed some years ago and
hope that Concert/Rhapsody will be a nice substitute.

Cheers,

	--jc

--
Ju:rgen Christoffel, GMD - Forschungszentrum Informationstechnik GmbH
E-Mail: christoffel@gmd.de or one of {ftp,news,web}master@gmd.de



***** Want to unsubscribe from this list?
***** Send mail with body "unsubscribe" to mac-perl-request@iis.ee.ethz.ch