[TUHS] Bourne shell and comments
ag4ve.us at gmail.com
Thu Apr 20 10:31:29 AEST 2017
This is a bit old (hope someone has archived it incase the account is ever
deleted) but this is the shebang history reference I've ref'd a few times
(comes right after the Wikipedia hits when searching for "shebang history"
in Google - for me anyway).
It'd be interesting to hear if the group finds any inaccuracies or knows of
anything more thorough on the topic.
On Apr 19, 2017 6:05 PM, "Steffen Nurpmeso" <steffen at sdaoden.eu> wrote:
> Sven Mascheck <mascheck at in-ulm.de> wrote:
> |On Wed, Apr 19, 2017 at 06:48:34AM +1000, Warren Toomey wrote:
> |> I was trying to configure C news on 2.9BSD today and I found that its
> |> Bourne shell doesn't grok # comments. The Bourne shell in 2.11BSD does.
> |> So I thought: when did the Bourne (and other) shells first grok # as
> |> indicating a comment? Was this in response to #! being added to the
> |> kernel, or was it the other way around? And was the choice of #!
> |> arbitrary, or was it borrowed from somewhere else?
> |> Datum point: 2.9BSD's kernel can recognise #!, but the sh can't
> recognise \
> |> #.
> |Dennis' email about #! to Berkeley is dated Jan 10 '80.
> |I've never seen any hint, how the bang in #! was chosen. Looks racy \
> |at least..
> |#! on BSDs was available as compile time option in 4.0BSD (~Oct '80?)
> |and default on 4.2BSD (~Sep '83).
> |BTW, AFAIK, the #! implementation in 2.8BSD (compile time option) is not
> |from research but seems to come from U.S. Geological Survey, Menlo Park.
> |The BSD csh hack in sh&csh (# special as first character in a file, \
> |came with 3BSD, also in '80.
> |I found # as comment character in the BSD-sh first in CSRG 4.1.snap
> |(~Apr '81, word.c). And at Bell Labs, as mentioned, it came with SysIII,
> |also ~81.
> |BTW, 4.3BSD ('86), and thus 2.10 BSD, brought an interesting change:
> |# is only recognized in non-interactive mode. In interactive mode
> |you actually get this:
> | $ # echo x
> | #: not found
> |This was not changed in 4BSD until sh was replaced by ash in 4.3 Net/2.
> Hmm. Kurt Shoens added # as a null() saying "The do nothing
> command for comments." before that (2BSD, file copyright 1979).
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