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Date:      Mon, 8 Dec 2014 10:23:59 -0800
From:      Garrett Cooper <yaneurabeya@gmail.com>
To:        Kirk McKusick <mckusick@mckusick.com>
Cc:        FreeBSD Hackers <freebsd-hackers@freebsd.org>, Erik Trulsson <Erik.Trulsson.1013@student.uu.se>, dickey@his.com, jkh@freebsd.org
Subject:   Re: Reason for reordering /usr/share/misc/termcap.src for /usr/share/misc/termcap ?
Message-ID:  <745168FD-F296-427D-9AEB-79FD42038324@gmail.com>
In-Reply-To: <201412081651.sB8GpbpO088722@chez.mckusick.com>
References:  <201412081651.sB8GpbpO088722@chez.mckusick.com>

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On Dec 8, 2014, at 8:51, Kirk McKusick <mckusick@mckusick.com> wrote:

>> Date: Mon, 08 Dec 2014 13:13:40 +0100
>> From: Erik Trulsson <Erik.Trulsson.1013@student.uu.se>
>> To: Garrett Cooper <yaneurabeya@gmail.com>
>> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org>,
>>        Kirk McKusick <mckusick@mckusick.com>, jkh@freebsd.org,
>>        dickey@his.com
>> Subject: Re: Reason for reordering /usr/share/misc/termcap.src for =
/usr/share/misc/termcap ?
>> X-ASK-Info: Message Queued (2014/12/08 04:13:49)
>> X-ASK-Info: Confirmed by User (2014/12/08 08:34:35)
>>=20
>> Quoting Garrett Cooper <yaneurabeya@gmail.com>:
>>=20
>>> Hi all,
>>> 	I'm trying to resolve an issue where usr.bin/vi is needed to =20
>>> preprocess share/termcap every time make buildworld is invoked on =20=

>>> FreeBSD. The termcap file reordering seems to have been done since =20=

>>> the BSD 4.4 Lite sources were imported into FreeBSD: =20
>>> =
https://svnweb.freebsd.org/base/projects/building-blocks/share/termcap/Mak=
efile?view=3Dmarkup#l15,
>>> https://svnweb.freebsd.org/base?view=3Drevision&revision=3D1638.
>>> I don't have history behind why this should be done (it's =
unfortunate
>>> because it appears to mangle the comment <-> entry mappings, and
>>> ultimately this gets put into termcap.db), and I was hoping that
>>> someone with additional history could fill in why this is being =
done.
>>> Thank you!
>>=20
>> It looks like it is done to put the most common (at the time it was =20=

>> written) terminal types early in the reordered termcap file.  This =20=

>> presumably so that programs reading termcap would be more likely to =20=

>> find the entry they wanted as quickly as possible.
>>=20
>> That would have been useful when termcap was just a plain text file, =20=

>> but if you are using termcap.db to look up terminal capabilities then =
=20
>> there doesn't seem to be much point to doing such reordering =
beforehand.
>=20
> I believe Erik Trulsson's answer is correct. Termcap had grown very
> large and on sub-1-MIP computers took a noticable delay to read on
> every startup of programs using it. So, it was reordered to reduce
> the startup time on common terminals. As Erik points out this =
optimization
> is no longer necessary as termcap is now placed in a database. Not to
> mention that there are far fewer entries in it today than there were
> at the peak of its existence.

Ok. I=92ll do some double-checking to see whether or not something=92s =
accessing the plaintext termcap file directly, but it helps to know the =
history behind this (especially when the history in the installed file =
gets muddled when ex is run on the file at build time).
Thanks!

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