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Help speeding up script

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# 1  
Old 04-27-2015
Help speeding up script
This is my first experience writing unix script. I've created the following script. It does what I want it to do, but I need it to be a lot faster. Is there any way to speed it up?

Code:
cat 'Tax_Provision_Sample.dat' | sort | while read p; do fn=`echo $p|cut -d~ -f2,4,3,8,9`; echo $p >> "$fn.txt"; done

Thank you.
Last edited by vgersh99; 04-27-2015 at 07:21 PM.. Reason: code tags, please!
# 2  
Old 04-27-2015
Hi

You could use sort directly instead of cat.
Cant say anything else without the content of the Tax_Provision_sample.dat.

hth
# 3  
Old 04-28-2015
Test this' (bashism's) run time
Code:
IFS="~"; while read -a p; do echo "${p[*]}" >> "${p[1]}${p[3]}${p[2]}${p[7]}${p[8]}.txt"; done <Tax_Provision_Sample.dat

You may want to save the old IFS beforehand. If need be, you can pipe sort's output into the loop.
This User Gave Thanks to RudiC For This Post:
JohnN6
# 4  
Old 04-28-2015
It's because you're running an external program for each line.

Here is an awk solution:

Code:
sort Tax_Provision_Sample.dat | awk -F~ '{f=$2 FS $4 FS $3 FS $8 FS $9 ".txt"; print $0 >> f; close(f);}'

Last edited by neutronscott; 04-28-2015 at 01:31 PM.. Reason: >>
This User Gave Thanks to neutronscott For This Post:
JohnN6
# 5  
Old 04-28-2015
Wow. That was a lot faster. Thanks!
# 6  
Old 04-28-2015
Quote:
Originally Posted by RudiC
Test this' (bashism's) run time
Code:
IFS="~"; while read -a p; do echo "${p[*]}" >> "${p[1]}${p[3]}${p[2]}${p[7]}${p[8]}.txt"; done <Tax_Provision_Sample.dat

You may want to save the old IFS beforehand. If need be, you can pipe sort's output into the loop.
You don't need to save IFS if you run it in a subshell:
Code:
(IFS="~"; while read -a p; do echo "${p[*]}" >> "${p[1]}${p[3]}${p[2]}${p[7]}${p[8]}.txt"; done) <Tax_Provision_Sample.dat

Code:
sort Tax_Provision_Sample.dat | (...)

This User Gave Thanks to MadeInGermany For This Post:
JohnN6
# 7  
Old 04-28-2015
Quote:
Originally Posted by neutronscott
It's because you're running an external program for each line.

Here is an awk solution:

Code:
sort Tax_Provision_Sample.dat | awk -F~ '{f=$2 FS $4 FS $3 FS $8 FS $9 ".txt"; print $0 > f; close(f);}'

Note that each file will only contain one line of the original file, namely the last occurence of a particular combination of those fields. If there can be more than one line with that combination you need to use >> instead of >, but you would need to empty the files beforehand...
This User Gave Thanks to Scrutinizer For This Post:
JohnN6
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