Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!unmvax!ncar!ames!amdahl!pacbell!pbhyf!rob
From: rob@pbhyf.PacBell.COM (Rob Bernardo)
Newsgroups: comp.mail.elm
Subject: Re: mailbox locking across multiple machines?
Keywords: elm, mail, lockf, fcntl
Message-ID: <4679@pbhyf.PacBell.COM>
Date: 10 Feb 89 22:50:45 GMT
References: <2434@eta.unix.ETA.COM>
Reply-To: rob@pbhyf.PacBell.COM (Rob Bernardo)
Distribution: na
Organization: Pacific * Bell, San Ramon, CA
Lines: 24

In article <2434@eta.unix.ETA.COM> rscott@eta.unix.ETA.COM (Rich Scott) writes:
+	Are there any patches/releases that use, say, lockf(3) or
+fcntl(2) to lock /usr/spool/mail/username so that only one instance
+of elm _on the network_ can read and modify it? Currently, elm only
+does this right for two simultaneous sessions on the same machine.
+Thanks ...

Well, you can't use file locking because on some systems file locking 
is used to lock the mail file against updates to the mail file; you 
don't want it locked against new mail coming in the whole time you're 
using elm. 

I don't know about previous versions of ELM, but ELM 2.2 can be 
configured with a non-default directory for temporary files (default = 
/tmp on most systems). This is the directory where elm creates the 
file that locks against multiple sessions with the same mail file. 
What you would need to do is configure ELM so that the directory for 
temporary files is one shared between all systems that can acces the 
mail spool directory. 
-- 
Rob Bernardo, Pacific Bell UNIX/C Reusable Code Library
Email:     ...![backbone]!pacbell!pbhyf!rob   OR  rob@pbhyf.PacBell.COM
Office:    (415) 823-2417  Room 4E750A, San Ramon Valley Administrative Center
Residence: (415) 827-4301  R Bar JB, Concord, California