[Tutor] spitshell for python

[Alan Gauld]

> I don't think so.  Typically there's a commonly accepted way to
> provide code that is legal under the shell and the language that
> will be ignored by python, but cause the shell to exec python
> with appropriate arguments.  As an example, this works as the
> first lines in a perl script:

That doesn't help me I'm afraid. You are going to have to 
explain what's happening in the perl code

> #!/usr/local/bin/perl

This bit I understand - it runs the perl interpreter :-)

> eval ' exec /usr/local/bin/perl -S $0 ${1+"$@"}'

And this evaluates a string as a perl instruction, or is 
it as a shell instruction? hmm probably the latter.

But what is inside the string? It looks like we are 
running another copy of perl to execute whatever 
the $0... arguments are? What is the -S option?

> if $running_under_some_shell;

And I assume this is a conditional that determines 
whether the eval gets executed depending on the shell, 
ie Bourne, Bash, csh etc?

So I'm guessing that what you want is a bit of Python 
code that will figure out which shell is running and 
execute a shell command in that dialect?

And the bit of shell to execute, in turn, runs some 
python script? 

Am I right? If so that sounds like it brings me back 
to execfile... so presumably I'm missing some magic 
in the line noise at the end of the eval statement...

Alan G.