How to enter escape character in a positional string argument from the command line?

[Chris Angelico]

On Thu, 22 Dec 2022 at 03:11, Stefan Ram <ram at zedat.fu-berlin.de> wrote:
>
> Lars Liedtke <lal at solute.de> writes:
> >Or you could have "native" bash ($SHELL) with WSL.
>
>   In this newsgroup, it would actually be obvious to use Python.

Less obvious than you might think - partly because bash is just so
dang good that it's really really hard to outdo it :) Sure, bash has a
lot of weird and wonky edge cases, but it's an incredibly practical
shell to use.

>   When commands are typed manually, this might be a bit verbose,
>   though. I mean
>
> os.chdir( r'C:\EXAMPLE' )
>
>   versus
>
> CD C:\EXAMPLE

Exactly. What's good for a programming language is often not good for a shell.

> class PythonShell( cmd.Cmd ):
>
>     intro = 'Welcome to the Python shell. Type help or ? to list commands.\n'
>     prompt = '(Python) '
>     file = None
>
>     def do_cd( self, arg ):
>         'change directory:  CD C:\EXAMPLE'
>         os.chdir( *parse( arg ))
>
>     def do_bye( self, arg ):
>         'Exit:  BYE'
>         print( 'Thank you for using the Python Shell!' )
>         return True

Sure, you can always create your own shell. But I think you'll find
that, as you start expanding on this, you'll end up leaning more
towards "implementing bash-like and/or cmd-like semantics in Python"
rather than "creating a Python shell". Shells, in general, try to
execute programs as easily and conveniently as possible. Programming
languages try to stay inside themselves and do things, with subprocess
spawning being a much less important task.

Fun challenge: see how much you can do in bash without ever forking to
another program. And by "fun", I mean extremely difficult, and by
"challenge" I really mean "something you might have to do when your
system is utterly hosed and all you have available is one root shell".

It's amazing how far you can go when your hard drive has crashed and
you desperately need to get one crucial login key that you thought you
had saved elsewhere but hadn't.

ChrisA