Xref: utzoo comp.unix.questions:12871 comp.lang.c:17660
Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!ukma!xanth!kremer
From: kremer@cs.odu.edu (Lloyd Kremer)
Newsgroups: comp.unix.questions,comp.lang.c
Subject: Re: lockfile/unix/c
Summary: O_CREAT observations
Keywords: c, unix, lockf
Message-ID: <8466@xanth.cs.odu.edu>
Date: 14 Apr 89 16:25:30 GMT
References: <6307@homxc.ATT.COM> <3012@hound.UUCP>
Followup-To: comp.lang.c
Organization: Old Dominion University, Norfolk, Va.
Lines: 21



In article <3012@hound.UUCP> rkl1@hound.UUCP (K.LAUX) writes:

>after opening a file with O_CREAT, I close the file, then
>reopen it with another open call, because O_CREAT will only let you
>write to the file, and I usually need read/write permission.


My experience has been that you can't assume any particular read/write
capability from a file opened with O_CREAT only.  O_CREAT alone will often
simply create the file (take out a directory entry under that name).  To be
portable, O_CREAT should always be combined with exactly one of O_RDONLY,
O_WRONLY, or O_RDWR, according to what you wish to do with the file.

O_TRUNC or O_EXCL are often combined with O_CREAT, also.


					Lloyd Kremer
					Brooks Financial Systems
					{uunet,sun,...}!xanth!brooks!lloyd