From mboxrd@z Thu Jan  1 00:00:00 1970
MIME-Version: 1.0
Date: Wed, 17 Apr 2013 17:52:33 +0100
Message-ID: <CAOw7k5g2BsJXqmgvFzbi36XCigzefmyBKycKSxwtHnB9TXGXiQ@mail.gmail.com>
From: Charles Forsyth <charles.forsyth@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Content-Type: multipart/alternative; boundary=089e010d8574f1cfd004da914f96
Subject: [9fans] pprint and exportfs (and others)
Topicbox-Message-UUID: 42d89ab4-ead8-11e9-9d60-3106f5b1d025

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In a few cases, the kernel will use pprint to put a diagnostic on the
standard error (file descriptor 2).
One of those is a warning that the process has used more than 100 file
descriptors.
That message is possibly obsolete and could be removed, but there are
others, such as
notifying an uncaught trap that are probably helpful to make visible.
In any case, as things stand, a busy exportfs might have many file
descriptors open,
provoking the diagnostic. Unfortunately, aux/listen and aux/listen1 connect
file
descriptor 2 to the incoming network connection. If the connection's
protocol is
not a simple, unstructured, textual one, diagnostics on the standard error
will cause confusion, in particular to devmnt.c if 9p is used.

/rc/bin/service files that start applications that run special protocols
might want to
redirect file descriptor 2; alternatively, perhaps aux/listen shouldn't
redirect fd 2 by
default: the few commands that do connect the remote user to shells, or
equivalent, including
telnetd and sshd could dup 1 to 2 when that was sensible.

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<div dir=3D"ltr">In a few cases, the kernel will use pprint to put a diagno=
stic on the standard error (file descriptor 2).<div style>One of those is a=
 warning that the process has used more than 100 file descriptors.</div><di=
v style>
That message is possibly obsolete and could be removed, but there are other=
s, such as</div><div style>notifying an uncaught trap that are probably hel=
pful to make visible.</div><div style>In any case, as things stand, a busy =
exportfs might have many file descriptors open,</div>
<div style>provoking the diagnostic. Unfortunately, aux/listen and aux/list=
en1 connect file</div><div style>descriptor 2 to the incoming network conne=
ction. If the connection&#39;s protocol is</div><div style>not a simple, un=
structured, textual one, diagnostics on the standard error</div>
<div style>will cause confusion, in particular to devmnt.c if 9p is used.</=
div><div style><br></div><div style>/rc/bin/service files that start applic=
ations that run special protocols might want to</div><div style>redirect fi=
le descriptor 2; alternatively, perhaps aux/listen shouldn&#39;t redirect f=
d 2 by</div>
<div style>default: the few commands that do connect the remote user to she=
lls, or equivalent, including</div><div style>telnetd and sshd could dup 1 =
to 2 when that was sensible.</div></div>

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