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Full Discussion: Performance issue with 'grep' command for huge file size
Operating Systems HP-UX Performance issue with 'grep' command for huge file size Post 302574529 by arb_1984 on Thursday 17th of November 2011 12:24:54 PM
Old 11-17-2011
Performance issue with 'grep' command for huge file size

I have 2 files; one file (say, details.txt) contains the details of employees and another file (say, emp.txt) has some selected employee names. I am extracting employee details from details.txt by using emp.txt and the corresponding code is:
Code:
while read line
do
emp_name=`echo $line`
grep -e $emp_name details.txt >> output.txt
done < emp.txt

Above code is working fine and I am getting expected result. But, this code is taking too much time (I don't have exact time, more than 6 hrs, later on cancelled the script) while the file size is huge. As an example, I have details.txt of around 2.5GB and record count is around 7.5lacs and the emp.txt has 55K employee name. Can you please suggest any other option/ command which will be better to handle such huge file. Thanks.
Last edited by vbe; 11-18-2011 at 09:33 AM.. Reason: attempt to use code tags ( fighting with fonts...)
 

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LEARN ABOUT DEBIAN

blockdiag

BLOCKDIAG(1)						      General Commands Manual						      BLOCKDIAG(1)

NAME

       blockdiag - generate block-diagram image file from spec-text file.

SYNOPSIS

       blockdiag [options] file

DESCRIPTION

       This manual page documents briefly the blockdiag commands.

       blockdiag is a program that generate block-diagram image file from spec-text file.

OPTIONS

       These  programs	follow	the  usual  GNU  command  line	syntax, with long options starting with two dashes (`-').  A summary of options is
       included below.	For a complete description, see the SEE ALSO.

       --version
	      show program's version number and exit

       -h, --help
	      Show summary of options

       -a, --antialias
	      Pass diagram image to anti-alias filter

       -c FILE, --config=FILE
	      read configurations from FILE

       -o FILE
	      write diagram to FILE

       -f FONT, --font=FONT
	      use FONT to draw diagram

       --fontmap=FONT
	      use FONTMAP file to draw diagram

       -s, --separate
	      Separate diagram images for each group

       -T TYPE
	      Output diagram as TYPE format

       --nodoctype
	      Do not output doctype definition tags (SVG only)

       --no-transparency
	      do not make transparent background of diagram (PNG only)

SEE ALSO

       The programs are documented fully by
       http://tk0miya.bitbucket.org/blockdiag/build/html/index.html

AUTHOR

       blockdiag was written by Takeshi Komiya <i.tkomiya@gmail.com>

       This manual page was written by Kouhei Maeda <mkouhei@palmtb.net>, for the Debian project (and may be used by others).

								   May	9, 2011 						      BLOCKDIAG(1)
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