Path: utzoo!attcan!uunet!mcvax!kth!draken!chalmers!myab!lars
From: lars@myab.se (Lars Pensj|)
Newsgroups: comp.unix.questions
Subject: Re: System V message queues?
Message-ID: <456@myab.se>
Date: 2 Mar 89 13:09:55 GMT
References: <561@pvab.PVAB.SE> <4043@ingr.com>
Reply-To: lars@myab.UUCP (Lars Pensj|)
Organization: Myab Gothenburg, Sweden
Lines: 21

In article <4043@ingr.com> crossgl@ingr.UUCP (Gordon Cross) writes:
>The correct way to use message
>queues for interprocess communication is to create it using a value for
>'key' that is known (or can be determined) by the other processes that wish
>to use the queue.  There is a function 'ftok' available that can be used to
>generate such a key.  It requires the path name of an existing file and an
>unique id (the manual suggests that this id should uniquely identify a
>project).  My personal opinion of 'ftok' is UGHHHH!  I usually just pick
>some random number and use that as the key then we register this number so
>no other project will use the same one.



My opinion of ftok() is that it should have been mandatory. If you use
ftok() on a local file, you will get a unique key. If you want more than
one unique key, use an id value of 0, 1 and so on for the same file.

Never use a random number, it can collide with other programs !
-- 
    Lars Pensj|
    lars@myab.se