Re: Linux Bash vs. Unix Bash

Rick Warner wrote:
>> plain "sh" on most unixes (besides linux) is usually a subset of
>> features that both bash and ksh has. they are like 92% overlap in
>> most syntax, but there are differences.
>
> A more correct statement is that bash and ksh are supersets of sh.
> AT&T created the reference implementation of sh; Korn (at AT&T) then
> created ksh as a superset of Bourne's sh.  bash is a much later
> superset.
>
> Script writers who want to ensure that their scripts work under all
> bastardizations of 'sh' should write to the USL reference
> implementation. Avoid ksh extensions, avoid bash extensions, avoid
> SCO extensions; just write to the pre-Novell buyout USL specs for sh
> and all should be fine.
>
> - rick warner

agreed, but I find the compromise worth it.
at least when writing for ksh, you get to do this:

#!/bin/ksh

This is reasonably likely to exist on many boxes, and those boxes where
ksh is not installed the script will fail in a cleaner, more obvious way.
What it *won't* do is "almost work", ie: look like it's working but
actually doing some things wrong.

And the fix, to make it work on a box where it doesn't, is simpler than
editing the script for a different shell.

in the bargain, ksh is a lot more useful than sh

it's a compromise between the really nice features of bash and the extreme
portability of strict USL sh. I find ksh just as handy as bash, and at the
same time almost as widely available as sh. so if a box here and there
needs to install ksh, I find that better than having a box _beleive_ it
can run my script without error because it has a /bin/sh, only to have
that box's sh do something dufferent than mine. or almost as bad, having
to work hard to write things that are very easy in ksh.

I figure even requiring ksh I'm still being 200 times nicer than for
example, any perl script and people are certainly not shy about writing
those.

Brian K. White  --  [email protected]  --  http://www.aljex.com/bkw/
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