Shell history (Re: bash conversion trouble.)

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

On Feb 26, 10:03am, Ray Andrews wrote:
}
} Is there a brief history of shells that one might read?

This:

http://www.softpanorama.org/People/Shell_giants/introduction.shtml

has the timeline mostly correct; but the author is so far off on the
relative merits of the Bourne and C shell scripting languages, for
example, as to make most of his editorializing ignorable.  He seems
to have some kind of axe to grind with Steve Bourne and wastes a lot
of words bashing him (no pun intended), but there is a lot of useful
source material quoted or linked.

(As an example, the Bourne language can be sensibly pre-parsed into an
execution tree -- the basis for zsh's eventual adoption of wordcode for
internal representation -- whereas the csh language makes no sense if
it is not executed in parallel with parsing.  I've even written self-
modifying csh programs that take advantage of this by overwriting the
tail of their own input file in the middle of a loop.)

This:

http://www.ibm.com/developerworks/library/l-linux-shells/

has a chart showing the timeline in detail, though to put zsh on a
direct line from csh is also misleading; it was written from scratch
and should probably have dotted lines from all of csh, ksh, and rc
as ideas were borrowed from all of those (the ksh ideas having been
taken from a [sometimes mis-] reading of the ksh manual pages, as
ksh implementations were still proprietary at that time).

Several of the O'Reilly Media books on shell programming also contain
chapters on shell history, which are accurate to varying degrees though
more correct than not.