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From: royle@tope.cs.indiana.edu (Keenan Royle)
Newsgroups: comp.unix.questions,comp.unix.ultrix,cs.unix.questions
Subject: Re: file and record locking questions (general)
Keywords: record,locking,ultrix
Message-ID: <1991Mar29.124756.18856@news.cs.indiana.edu>
Date: 29 Mar 91 17:47:20 GMT
References: <1991Mar29.040736.18783@bronze.ucs.indiana.edu>
Distribution: na
Organization: Computer Science Department, Indiana University
Lines: 45

To the best of my knowledge:

yes it is portable. (not just Ultrix)

flock locks a file.
lockf and fcntl can lock records in files (or the whole file).
lockf is just a nice front-end to fcntl.

All locks are advisory.

Ultrix is BSD based.  Portablity to system 5 may be trickier.

I can't remember the name of the sys5 routine (if it is different)
But I have used it.

In article <1991Mar29.040736.18783@bronze.ucs.indiana.edu> streib@silver.ucs.indiana.edu (Allan Streib) writes:
>Just a couple of general questions on file and record locking under
>UNIX:
>
>(These questions are all based on my study of Ultrix 4.2 man pages)
>
>- flock (2) and lockf (3) can be used to control concurrent access to
>files, allowing cooperating processes to perform consistent operations
>on files.  I understand that these system calls are advisory, and do
>not (apparently) lock the file to non-cooperating processes.
>
>- I can apparently use fcntl (2) with commands FGETLK, FSETLK, and
>FSETLKW to facilitate concurrent file acccess. 
>
>These commands are not mentioned in Rochkind's _Advanced UNIX
>Programming_ text.  Are these Ultrix enhancements, or are these
>portable?
>
>Thanks for any insight. 
>
>-Allan (streib@silver.ucs.indiana.edu)
>
>


-- 

Keenan Royle
royle@cs.indiana.edu                         	postmaster@cs.indiana.edu
royle@iubacs.bitnet