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Full Discussion: Speeding up shell script with grep
Top Forums Shell Programming and Scripting Speeding up shell script with grep Post 302994613 by RudiC on Saturday 25th of March 2017 06:20:42 AM
Old 03-25-2017
Using grep -f works, but with two files as large as indicated will take its (serious) time, and may eventually run out of memory. Try
Code:
sort master.csv new | uniq -d

, then use the resultant file in similar way (uniq -u) to extract unique values from either original file.
Comparison of both approaches on ~20k files:
Code:
time grep -ffile2 file1
real    0m0.352s
user    0m0.280s
sys     0m0.052s
time sort file[12] | uniq -d
real    0m0.037s
user    0m0.032s
sys     0m0.004s

EDIT: Times spent for two files with roughly 4E6 entries each, and about 1E6 lines overlap (on a two processor linux host):
Code:
time sort file[12] | uniq -d > f1
real    0m14.975s
user    0m27.048s
sys     0m0.792s
time sort file1 f1 | uniq -u > f2
real    0m9.331s
user    0m16.488s
sys     0m0.572s

Last edited by RudiC; 03-25-2017 at 01:22 PM..
 

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lr_environment

LR_ENVIRONMENT.IN(1)					  LogReport's Lire Documentation				      LR_ENVIRONMENT.IN(1)

NAME

       lr_environment - Export Lire configuration in shell script form

SYNOPSIS

       eval `lr_environment`

DESCRIPTION

       The lr_environment command is used to import the Lire configuration in Lire shell scripts.

       All of Lire configuration variables will be written in a format that can be evaled by the shell.

       Shell scripts don't usually have to use that command, since it is done by the defaults file sourced by each command.

       The old names used by when the configuration was done in shell script are also exported by this script for backward compatibility.

AUTHOR

	 Francis J. Lacoste <flacoste@logreport.org>

VERSION

       $Id: lr_environment.in,v 1.12 2006/07/23 13:16:33 vanbaal Exp $

COPYRIGHT

       Copyright (C) 2003 Stichting LogReport Foundation LogReport@LogReport.org

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       You should have received a copy of the GNU General Public License along with this program (see COPYING); if not, check with
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