Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!tektronix!percival!bucket!leonard
From: leonard@bucket.UUCP (Leonard Erickson)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Question on DOS APPEND command
Keywords: APPEND
Message-ID: <1387@bucket.UUCP>
Date: 6 May 89 04:53:43 GMT
References: <762@ednor.UUCP>
Reply-To: leonard@bucket.UUCP (Leonard Erickson)
Organization: Rick's Home Grown Unix; Portland, OR
Lines: 50

In article <762@ednor.UUCP> sgr@ednor.UUCP (Steve Reppucci) writes:
<
<Here's a question concerning the DOS APPEND command.
<
<I'm trying to open a file from a C program (using either open() or
<fopen()... they behave similarly).  I'm running DOS 3.3, and compiling
<with MSC-51 (although I get the same results if I compile with TC-20).
<I have set a 'data search path' using the APPEND command.  It seems
<that if the file I'm attempting to open doesn't exist, AND a file
<with the same name exists in a directory that's in the search path,
<then that file (in the search path) gets opened (and overwritten).
<Note that this happens even though I've specified the full DOS pathname
<in the open call.
<
<My question is, is this correct behavior ??  Seems unlikely to me that
<the APPEND search path should be accessed at all if the file is opened
<using a full pathspec.  And is this a compiler problem, or a DOS problem ?
<Is there a workaround ??

This "normal" behavior for APPEND. The problem is that APPEND is an
*external* DOS command rather than an internal one. I'm not sure how
APPEND works, but I suspect it ties into the "file not found" error or
some such. 

APPEND is kludged onto DOS rather than integrated into it. It takes
over if DOS returns "file not found". So if you are using it, it *will*
return a file in another directory on the search path if no file is
found in the current directory. DOS doesn't even know that the file is
in another directory!

Try this:
create a file in a directory on the APPEND path
go to a different directory
do a dir using wildcards that would find the file

If no files in the current dir match, dir will cheerfully list the
file *as if it was in the current directory*! In other words, APPEND
works by *lying* to DOS! My advice (and that of everyone who is aware
of APPEND's "odd" behavior is not to use it! It is more dangerous than
helpful. Especially since not all DOS functions use it. (I think that
only the find first and find next functions tie into it...) This way
lies massively inconsistent behavior. Such as opening a file with
a wordprocessor, editing it, and then having the wp crash on exit
because when it tries to rename the original file, the DOS rename call
can't find it! Blecch!
-- 
Leonard Erickson		...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I'm all in favor of keeping dangerous weapons out of the hands of fools.
Let's start with typewriters." -- Solomon Short