Off topic: python vs. sh (Re: [Webware-discuss] cvs update: webkit script for unix rc/init)

[Terrel S. <tsh...@tr...>]

Ian Bicking wrote:

> Terrel Shumway <tsh...@tr...> wrote:
> > Why does this start with "#!/bin/sh" instead of "#!/bin/env python"?
> >
> > I always wonder why intelligent python programmers write sh scripts.  Python is obviously *available*.   Then again ... I do use perl once in while. 8-)
>
> Perhaps part of the reason is that the python script would end up
> doing its main action with os.system(), which is like running a shell
> script, with all the advantages and disadvantages.  Doing things like
> redirecting output is not easy in Python (even possible? Without using
> os.system()?)  That makes it bad as a control language.
>

I have been contemplating a module shell.py to take care of the I/O redirecting without using os.system (which IS exactly running a shell). Avoiding os.system avoids 200 security holes related to argument quoting and parsing and race conditions while files are opened and closed.  80% of the stuff you do with a shell script requires spawning a tiny program to do what is built in to the language or the standard library in python. Why spawn /bin/kill (50 system calls and a ton of quoting and parsing) when you can just make the call directly with os.kill()?  No, it is not that cut and dried, but there are a lot fewer hoops to jump through in python.  Maybe it the challenge of doing a lot with little, like writing programs for an 8-bit CPU to run in 4KB of RAM, or writing a mail server in perl. 8-)

I have already written pieces of this shell module, but have never put them all together.