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Full Discussion: Help on cat with sed!
Top Forums Shell Programming and Scripting Help on cat with sed! Post 302338528 by kbalaji_uk on Tuesday 28th of July 2009 07:20:11 AM
Old 07-28-2009
Help on cat with sed!
Hi All!

I have a script having one statement like.

cat xfile | sed 's/A/a/g' > xfile

I have two boxes which have similar version of linux running but one is greater in speed compared to other. Lets say A is faster than B.

A which is faster writes output as NULL
B which is slower comparatively to A writes the entire content with A replaced to a
. Though I know its not a good practice. I want to know why is this behavior. Is there some delay writing in one compared to the other ? I remmeber comming across this jargon in buffer cache

Thanks
Balaji Kamal Kannadassan
 

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LEARN ABOUT PLAN9

scriptreplay

SCRIPTREPLAY(1) 						   User Commands						   SCRIPTREPLAY(1)

NAME

       scriptreplay - play back typescripts, using timing information

SYNOPSIS

       scriptreplay [options] [-t] timingfile [typescript [divisor]]

DESCRIPTION

       This program replays a typescript, using timing information to ensure that output happens in the same rhythm as it originally appeared when
       the script was recorded.

       The replay simply displays the information again; the programs that were run when the typescript was being  recorded  are  not  run  again.
       Since  the same information is simply being displayed, scriptreplay is only guaranteed to work properly if run on the same type of terminal
       the typescript was recorded on.	Otherwise, any escape characters in the typescript may be interpreted differently by the terminal to which
       scriptreplay is sending its output.

       The timing information is what script(1) outputs to standard error if it is run with the -t parameter.

       By  default,  the typescript to display is assumed to be named typescript, but other filenames may be specified, as the second parameter or
       with option -s.

       If the third parameter is specified, it is used as a speed-up multiplier.  For example, a speed-up of 2	makes  scriptreplay  go  twice	as
       fast, and a speed-up of 0.1 makes it go ten times slower than the original session.

OPTIONS

       The first three options will override old-style arguments.

       -t, --timing file
	      File containing script's timing output.

       -s, --typescript file
	      File containing script's terminal output.

       -d, --divisor number
	      Speed  up  the  replay  displaying  this	number of times.  The argument is a floating point number.  It's called divisor because it
	      divides the timings by this factor.

       -m, --maxdelay number
	      Set the maximum delay between transcript updates to number of seconds.  The argument is a floating point number.	This can  be  used
	      to avoid long pauses in the transcript replay.

       -V, --version
	      Display version information and exit.

       -h, --help
	      Display help text and exit.

EXAMPLE

       % script --timing=file.tm script.out
       Script started, file is script.out
       % ls
       <etc, etc>
       % exit
       Script done, file is script.out
       % scriptreplay --timing file.tm --typescript script.out

SEE ALSO

       script(1)

COPYRIGHT

       Copyright (C) 2008 James Youngman
       Copyright (C) 2008 Karel Zak

       This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU-
       LAR PURPOSE.

       Released under the GNU General Public License version 2 or later.

AUTHOR

       The original scriptreplay program was written by Joey Hess <joey@kitenet.net>.  The program was re-written in C	by  James  Youngman  <jay@
       gnu.org> and Karel Zak <kzak@redhat.com>.

AVAILABILITY

       The  scriptreplay  command  is  part of the util-linux package and is available from Linux Kernel Archive <https://www.kernel.org/pub/linux
       /utils/util-linux/>.

util-linux							  September 2011						   SCRIPTREPLAY(1)
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