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From: Dan Cross <crossd@gmail.com>
To: Anthony Martin <ality@pbrane.org>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] A question about ls(1)
Date: Sun, 28 Apr 2019 07:47:35 -0400	[thread overview]
Message-ID: <CAEoi9W7z+ZvVpBPignn3sU_CFBNwTDgt=SPe_4itjxDdBg2hWw@mail.gmail.com> (raw)
In-Reply-To: <20190427141655.GA8310@alice>

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On Sat, Apr 27, 2019 at 10:26 AM Anthony Martin <ality@pbrane.org> wrote:

> From at least V2 to V6, the ls(1) command would not
> show directory entries whose names began with a '.'
> unless the -a flag was supplied.
>
> This was changed in V7: only the directory entries
> for "." and ".." would be skipped by default.
>
> All further versions of Research Unix retain the
> convention of V7 and Plan 9 ultimately made it
> unnecessary. However, BSD and its descendants did
> not follow suit. Instead, they continued behaving
> like V6 with an additional -A flag to emulate V7.
>
> Was the initial behavior intentional or just a
> matter of expediency?
>

I believe it's been publicly stated that it was a mistake in early Unix.
Apparently, Rob Pike had a Google+ post to this effect back in 2012 (or
earlier): I see a reference to it from another mailing list around that
time. Unfortunately, the Google+ content is now lost. Rob, do you have a
copy?

Who made the change and what was their motivation?
> Was it a reaction to the intentional hiding of what
> came to be known as "dot files"?


Speaking from memory, I think the intent was to avoid showing '.' and '..',
and that a programming error accidentally hid all dotfiles; probably this
went unnoticed because there just weren't many of them at the time. This
was corrected in 7th Edition, but the existing behavior had already escaped
into the world via Berkeley.

I suspect the "dot file" convention came later, as a side-effect of
observed behavior of ls.

        - Dan C.

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  parent reply	other threads:[~2019-04-28 11:48 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-27 14:16 Anthony Martin
2019-04-27 15:38 ` Warner Losh
2019-04-27 15:42   ` Larry McVoy
2019-04-28 23:59   ` Warner Losh
2019-04-28 11:47 ` Dan Cross [this message]
2019-04-28 12:00   ` arnold
2019-04-28 14:44   ` jcs
2019-04-28 16:15   ` Bakul Shah
2019-04-27 20:11 Norman Wilson
2019-04-27 23:03 Noel Chiappa
2019-04-28 16:54 Norman Wilson
2019-04-28 19:45 ` Jon Forrest
2019-04-28 20:00   ` Bakul Shah
2019-04-29 18:05     ` Michael Kjörling
2019-04-29 20:37       ` Warner Losh
2019-04-29 20:44       ` Christopher Browne
2019-04-30  6:44         ` Michael Kjörling
2019-04-30  7:24           ` Kurt H Maier
2019-04-30 10:35             ` Wesley Parish
2019-04-29 22:32       ` Bakul Shah
2019-04-30 11:52         ` Theodore Ts'o
2019-04-28 22:16   ` Thoma Paulsen
2019-04-29  0:53     ` John P. Linderman

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