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From: rjchen@phoenix.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: stupid COMMAND.COM  (WAS:  DOS enviroment size)
Message-ID: <134@phoenix.PRINCETON.EDU>
Date: Fri, 13-Mar-87 12:50:47 EST
Article-I.D.: phoenix.134
Posted: Fri Mar 13 12:50:47 1987
Date-Received: Sat, 14-Mar-87 09:07:32 EST
References: <2091@ncoast.UUCP> <409500003@prism> <2986@iuvax.UUCP> <12572@watnot.UUCP> <2438@dalcs.UUCP>
Reply-To: rjchen@phoenix.UUCP (Raymond J Chen)
Organization: Princeton Univ. Computing and Information Technology
Lines: 30
Keywords: DOS substitutions
Summary: DOS *does* interpret ">" and "<" when on the command line

In article <2438@dalcs.UUCP> dalegass@dalcs.UUCP writes:
>> [general discussion on inability to pass various marks of punctuation
>>  on the command line since they are DOS metacharacters.]
>
> ...I've seen the source code for Aztec C, and redirection is taken care
>of from the program which is executed, and is not a trapping at the DOS
>level. ...
>
>When DOS gives control to a .com or .exe file, it simply passes the whole
>command line to it, and let's it do what it wishes with the info.
>I think, however, that piping '|' *is* intercepted at the DOS level,
>whereas the '>' and '<' redirections are not.
>
>-dalegass@dalcs

I scribbled up a quick assembly language program which does an UNWS,
and merely call it with UNWS <infile >outfile.  My program just reads
everything off stdin and dumps it to stdout.  So DOS >does< catch the
">" and "<" and takes them out.

I don't know why Aztec C does all that redirection handling, but MIX C
(don't laugh) also does the same thing in its startup routine.  They
do it presumably because MIX C was originally a CP/M compiler, and CP/M
does not handle redirection.  Perhaps they were too lazy to remove it
from their MSDOS version, or maybe they know something we don't.

-- 
-- Raymond Chen, BITNET: (preferably) 6101695@pucc, rjchen@pucc
                 ARPA: rjchen@phoenix.PRINCETON.EDU
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