Path: utzoo!utgpu!water!watmath!clyde!rutgers!mit-eddie!husc6!cmcl2!brl-adm!brl-smoke!gwyn
From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.unix.wizards
Subject: Re: R/O root (was: Jerry Pournelle on UNIX)
Message-ID: <7154@brl-smoke.ARPA>
Date: 21 Jan 88 16:43:13 GMT
References: <1495@osiris.UUCP> <2126@haddock.ISC.COM> <1497@osiris.UUCP> <5247@elroy.Jpl.Nasa.Gov> <39244@sun.uucp> <1438@hplabsz.HPL.HP.COM>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 14

In article <1438@hplabsz.HPL.HP.COM> jin@hplabsz.UUCP (Tai Jin) writes:
>If the root filesystem is mounted read-only, will pipes continue to work?

I assume you mean, once everything else has been taken care of.
Pipes are implemented in different ways on different versions of
UNIX.  The only ones that should have trouble are those where
pipes are implemented by ripping off free inodes from the
designated "pipe device" (which was always the root device on
really old UNIXes, e.g. 6th Edition), only if the pipe device is
the same as the root filesystem device.  4BSD systems where
pipes are socketpairs and 8th or 9th Edition UNIX where pipes
are cross-coupled full-duplex streams (my personal favorite) do
not have their pipes directly dependent on the root filesystem
being writable.