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From: gnu@l5.uucp (John Gilmore)
Newsgroups: net.bugs.4bsd
Subject: Re: file locking misconception
Message-ID: <363@l5.uucp>
Date: Fri, 27-Dec-85 02:41:22 EST
Article-I.D.: l5.363
Posted: Fri Dec 27 02:41:22 1985
Date-Received: Sat, 28-Dec-85 01:41:42 EST
References: <5507@allegra.UUCP>, <6220@utzoo.UUCP> <7022@ki4pv.UUCP>
Organization: Nebula Consultants in San Francisco
Lines: 9

In article <7022@ki4pv.UUCP>, tanner@ki4pv.UUCP (Tanner Andrews) writes:
>                                                    there's no real
> excuse for a read-only prog to need to lock a file if the write-file
> prog successfully locks the damned thing anyway.

Uh, suppose the readers want a consistent copy of the file?  flock(),
at least in 4.2BSD, is an *advisory* lock -- it doesn't stop anybody
from doing anything with the file except flock() it again.  Readers can
use shared locks and writers use exclusive locks, for many applications.