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Top Forums Shell Programming and Scripting Speeding up shell script with grep Post 302994602 by dunryc on Saturday 25th of March 2017 04:37:32 AM
Old 03-25-2017
Speeding up shell script with grep

HI Guys hoping some one can help

I have two files on both containing uk phone numbers

master is a file which has been collated over a few years ad currently contains around 4 million numbers

new is a file which also contains 4 million number i need to split new nto two separate files one which contains number that already exist in master and one which contains numbers that don't already exist in master. I can do this but it takes around 80 hours to complete !! can any one offer any suggestions on how to speed this up ?

Code:
while read -r phone_number; do

        echo  "checking master for phone number $phone_number"

        if grep "$phone_number" master.csv; then
  
           echo "$phone_number already exists in master file "
          echo "$phone_number" >> unusable_numbers    
        else

           echo "$phone_number looks good we can use this saving to usable_numbers"
           echo "$phone_number" >> usable_numbers 

        fi

done < new

any help would be gratefully appreciated

Last edited by RudiC; 03-25-2017 at 06:58 AM..
 

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ATF-SH(1)						    BSD General Commands Manual 						 ATF-SH(1)

NAME
atf-sh [-s shell] -- interpreter for shell-based test programs SYNOPSIS
atf-sh script DESCRIPTION
atf-sh is an interpreter that runs the test program given in script after loading the atf-sh(3) library. atf-sh is not a real interpreter though: it is just a wrapper around the system-wide shell defined by ATF_SHELL. atf-sh executes the inter- preter, loads the atf-sh(3) library and then runs the script. You must consider atf-sh to be a POSIX shell by default and thus should not use any non-standard extensions. The following options are available: -s shell Specifies the shell to use instead of the value provided by ATF_SHELL. ENVIRONMENT
ATF_LIBEXECDIR Overrides the builtin directory where atf-sh is located. Should not be overridden other than for testing purposes. ATF_PKGDATADIR Overrides the builtin directory where libatf-sh.subr is located. Should not be overridden other than for testing purposes. ATF_SHELL Path to the system shell to be used in the generated scripts. Scripts must not rely on this variable being set to select a specific interpreter. EXAMPLES
Scripts using atf-sh(3) should start with: #! /usr/bin/env atf-sh Alternatively, if you want to explicitly choose a shell interpreter, you cannot rely on env(1) to find atf-sh. Instead, you have to hardcode the path to atf-sh in the script and then use the -s option afterwards as a single parameter: #! /path/to/bin/atf-sh -s/bin/bash ENVIRONMENT
ATF_SHELL Path to the system shell to be used in the generated scripts. SEE ALSO
atf-sh(3) BSD
September 27, 2014 BSD
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