scripting

Bennett Todd bet at rahul.net
Wed Jul 14 06:03:17 PDT 2004


2004-07-14T10:39:13 Björn Lindberg:
> ksh was first created in 1983, but the most popular version was
> ksh88, released in 1988. It was proprietary, but widely installed
> because most UNIX systems bought it to include as their POSIX
> shell.

I had relatively little exposure to System V based Unixes. I mostly
worked with BSD-derived Unixes until Linux came around. So I never
really got any exposure to ksh, when I moved beyond classic Bourne
Shell it was to bash.

> POSIX 1003.2 was finalized in 1992, but as far as I know bash was
> not created until later.

The configure script in the bash-1.14.7 tar.gz from ftp.gnu.org is
from October 31, 1991. As I recall things, bash was being very
actively hacked to track the standard as it developed; stuff that
the bash maintainers grudgingly agreed to support but disapproved of
was conditional under POSIXLY_CORRECT. There was a pretty good
stretch when bash was the only fully POSIX-compliant shell. While
some of the enhancements over and above /bin/sh were derived from
the then version of ksh, either they weren't adopted unchanged, or
else other things changed that ksh took a while to catch up to (I
don't know which).

> I am not able to find information on when bash was first available
> (it being open source, this may very well have been a gradual
> introduction), but bash 2.0 was released December 1996 according
> to a changelog file in the sources.

Bash was available long before 2.0, it was one of the earlier major
GNU programs --- understandably, it's nearly as fundamental as an
emacs and a C compiler.

> Bash didn't become important until Linux started being widely
> adopted, [...]

"become important" is hard to quantify. Long before Linux came
around, many of us enjoyed working on other Unix systems, and for at
least some of us, the standard working pattern was to put all the
GNU stuff into /usr/local/bin and put that at the front of our PATH,
giving us the finger-feel of a GNU system wherever we were.

> [...] so I have a hard time imagining that it had any influence on
> the POSIX process at the time.

I don't know how influential bash was on the POSIX process, but even
if little feedback made it back from bash to POSIX, bash was still
tracking the standard pretty tightly as it developed.

> 	The 1988 version of ksh [...] was a source document for the
> 	IEEE POSIX and ISO shell standards.

That's certainly the case, some POSIX extensions over classic
/bin/sh behavior were inspired by similar ones in ksh.

Really, it's a shame that ksh was locked up, proprietary closed
source, for those many years when bash came of age. The two shells
are so similar.

But my real favourite shell is so different from both that it dodges
the whole issue. rc rules!

:-)

-Bennett
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