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Date: Mon, 02 Jul 2001 07:31:32 -0700
To: russell christian sears <sears AT cis DOT ohio-state DOT edu>, <cygwin AT cygwin DOT com>
From: Randall R Schulz <rrschulz AT cris DOT com>
Subject: Re: 1.3.2, 1.1.8: Pipelines losing data?  (Windows 2000)
In-Reply-To: <Pine.GSO.4.33.0107020920330.29369-100000@beta.cis.ohio-sta
 te.edu>
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Russell,

Depending on the terminal you're using, which termcap / terminfo entry 
you've specified and the terminal window's size, less will produce 
different literal output sequences as it paginates and line-wraps its 
input. (Although I would have thought that if the output was not a tty, it 
would forgo such manipulations and act just like cat.)

You really shouldn't use a program explicitly designed for visual display 
on a terminal to feed a pipe to grep or any other processor.

Just grep the target file.

Randall Schulz
Mountain View, CA USA


At 06:21 2001-07-02, russell christian sears wrote:
>I have found a problem using less and grep to search a file.  The file is 
>available at: http://www.cis.ohio-state.edu/~sears/file.txt (It is over 1 
>megabyte, so I did not include it in this message.)
>
>I am using bash, and a complete, current installation of cygwin.
>
>When I run the command `less file.txt | grep cygwin` it sometimes fails to 
>find a match in the file, even though the file does contain the string.
>
>It seems to be sporadic, but I have been able to reproduce the problem on 
>three machines, each of which ran at about 700mhz.  Other commands that 
>seem to work as expected follow:
>
>less file.txt | cat | grep cygwin
>cat file.txt | grep cygwin
>grep cygwin file.txt
>
>If you have difficulty reproducing the bug, try running the command 
>multiple times (eg: by repeating <up-arrow>, <enter> rapidly).  Some 
>installations will only rarely have a problem, others will rarely yield 
>the correct result.  On systems that usually produce the correct result, 
>re-running the command rapidly seems to increase the likelihood of the 
>problem ocurring.
>
>Also, the string "cygwin" always appears at the end of a line in the file, 
>which may be related to this bug.
>
>I have tried both version 1.1.8 and the current cygwin distribution. 
>(1.3.2)  Both seem to suffer from this problem.
>
>As a control, I've checked this against a Linux system, and the bug did 
>not exist there.
>
>Below, the mount mode is listed as textmode.  The bug exists under binmode 
>as well.
>
>...


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