Re: [dev] Shell vs C where is the border?

From: Markus Wichmann <nullplan_AT_gmx.net>
Date: Tue, 11 Mar 2014 20:31:01 +0100

On Mon, Mar 10, 2014 at 09:22:39PM +0100, Paul Onyschuk wrote:
> On Mon, 10 Mar 2014 20:39:08 +0100
> Szymon Olewniczak <szymon.olewniczak_AT_rid.pl> wrote:
>
> > But having so many individual programs is more harder to use that just
> > one (we need to run more commands), so reasonable would be to combine
> > all this commands to one script which would do all this work
> > automaticaly. So what solution would be better in your opinion? When
> > we should use shell scripts and when write new C programs to achieve
> > our goals?
>
> My mail probably will be bounced, but anyway.
>
> It (pipes or lack of them) can be abused either way. Example of way too
> many command line flags (GNU ls):
>
> $ ls --help | awk '/^ {2,6}-/{i++} END{print i}'
> 58
>

Yeah, you just noticed that the GNU guys always do way too much.

> Yet you won't likely use more than a dozen options offered by ls ever
> (and fewest on daily basis). Those rare cases, when you need something
> specialized could be solved by sed/awk and other filters. Still they
> somehow managed to squeeze all those flags there - someone really hates
> pipes.
>

The more I read of POSIX, the more I think those options are only there
because they were easy to add to some specific implementations. Which,
of course, locks the specification ever more to fewer and fewer
implementations, and when you try to do something really crazy and new,
like using a new language (go) or a new paradigm (haskell) then good
luck getting that to conform.

Apart from that, even using C - as was ordained by Saints K&R - you have
to jump through some hoops to conform to SUSv3. That's why sbase and
ubase don't even try.

> Counter example would be man(1) command (this is personal opinion).
> Some implementation are doing something similar to that:
>
> $ zcat some-manpage.1.gz | eqn | grap | pic | tbl | vgrind | refer \
> | troff | more
>
> This is running every time when you type "man some-manpage". Filter
> approach of *roff made sense, when it was used for creating documents
> for printing (and it was often most CPU intensive command on the box
> according to some accounts).
>

You forgot the

find $MANPATH -name 'some-manpage.[0-9].*'

But then, this is really necessary, isn't it? I mean, you can use
catpages, which are basically preprocessed manpages, but those aren't
taylored to the terminal you are running it on, and usually they have
page headers and footers that distract when reading.

Apart from that, I have yet to see a better documentation system than
man.

Ciao,
Markus
Received on Tue Mar 11 2014 - 20:31:01 CET