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From: friedl@vsi.UUCP (Stephen J. Friedl)
Newsgroups: comp.unix.questions,comp.unix.wizards,comp.lang.c
Subject: Re: Writing to A NON-Existing File in "C"
Summary: Please do *not* use access to see if a file exists
Keywords: C program, NON-EXISTING File, flushed results
Message-ID: <549@vsi.UUCP>
Date: 16 Apr 88 02:28:01 GMT
References: <9654@jplgodo.UUCP> <10285@steinmetz.steinmetz.ge.com> <147@obie.UUCP>
Distribution: na
Organization: V-Systems, Inc. -- Santa Ana, CA
Lines: 31

In article <9654@jplgodo.UUCP> deutsch@jplgodo.UUCP (Michael Deutsch ) writes:
> I have a "C" program that records the program results into a file,
> provided that file already exists.  In case the file DOES NOT exist
> I want the program to function identically but the results should
> be flushed down the tube, i.e. nowhere, i.e.  written to a nong
> file?

Then (William E. Davidsen Jr) replies:
>  [little C fragment to do the above]

In article <147@obie.UUCP>, wes@obie.UUCP (Barnacle Wes) writes:
> I'd do it slightly different.  Unless you need speed, try using
> access(2) to determine if the file is available to you, and if not
> open /dev/null for writing:
>
> [little C fragment to do the above]

AAAAAAAAAARGH!  Please do not use access(2) as a handy-dandy
"does the file exist?" function.  It is designed to be used
by set-{user,group}-id programs to see if the underlying user
has permission to access the file in the requested manner.
I hate to sound like a flamer, but programmers who do not
understand the troubles with access(2) should probably not
use it; you will make life difficult for somebody down the
road.  Stat(2) can be used to do the same thing with just a
little extra code.

I wrote an "accfile(3)" function that does what you *think*
access(2) is doing; send me a note to get a copy.

Steve Friedl, resident access(2)-basher

-- 
Steve Friedl   V-Systems, Inc.   "Yes, I'm jeff@unh's brother"
friedl@vsi.com  {backbones}!vsi.com!friedl  attmail!vsi!friedl