On 12/21/22 11:22, Chris Angelico wrote:
On Thu, 22 Dec 2022 at 03:11, Stefan Ram <r...@zedat.fu-berlin.de> wrote:
Lars Liedtke <l...@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 you make a statement like that, Chris, you should also note that
every single one of those "wonky edge cases" is documented down to the
last dotted i. Bash's docs will kill a good sized pulp tree, needing
around a ream of paper to print on a duplex printer. I know, I did it
around a decade ago. If you like to write scripts, having a dead tree
copy of the docs at your elbow in incredibly useful. That huge man page
does not cover it like the printed docs do.
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
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, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/>
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