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From: keith@sdscal.UUCP (Keith Jones)
Newsgroups: comp.sys.ibm.pc
Subject: Re: dir | more
Summary: Strange files are made by COMMAND.COM when using pipe in MS-DOS
Message-ID: <208@sdscal.UUCP>
Date: 23 Mar 90 21:17:32 GMT
References: <2165@orbit.cts.com> <12503@ucsd.Edu>
Organization: Stream Data Systems, Calgary, Alberta
Lines: 37

In article <12503@ucsd.Edu>, steve@wintermute.ucsd.edu ({Darkavich}) writes:
> In article <2165@orbit.cts.com> cheangkk@pnet51.orb.mn.org (Pitt Cheang) writes:
> >When I tyied to dir the root directory of my hard disk , floppy disk with the
> >more , I always got two strange file name with 0 byte, the file name contains
> >mostly number with 8 characters long, no extention name.
>
> This behaviour can be seen anytime you use the pipe '|' 
> I do not really know why dos creates these files...

I'm sure I'm not going to be the only one to answer this but ...

These files are created by COMMAND.COM because MS-DOS has no real method for
providing pipes between processes ... you can only have one process at a
time so you take the output of the first process, save it in a temp file,
and then feed this temp file into the second process.  There looks to be a
little more than this to it, but the end effect is the same.

For example:

C:\TEMP> DIR | MORE

is the same as

C:\TEMP> DIR > 0E0C1D45
C:\TEMP> MORE < 0E0C1D45
C:\TEMP> DEL 0E0C1D45

Some command processors for the Amiga did this to implement pipes, even
though the Amiga OS ostensibly allows multiple processes.

I hope this sheds some light on the problem.

Keith.
-- 
Keith Jones			...!calgary!spycal!sdscal!keith
Stream Data Systems		I don't have a signature because my pen
Calgary, Alberta, Canada	keeps scratching up my monitor.