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Performance analysis sed vs awk

 
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# 8  
Old 07-06-2012
You can improve the awk program performance dramatically by making it exit after the end of the range. This stops it reading the other three-quarters of the file. I don't know how to get sed to exit early (or if it is possible).

Code:
time awk 'NR > 26000 { exit };(NR>=25000)&&(NR<=26000)' filename

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# 9  
Old 07-06-2012
Good point, the sed version would be:
Code:
sed -n '25000,26000 p; 26000q' filename

# 10  
Old 07-06-2012
Good call on the backticks ; I think the last instance in which I used time for more than one command I was stringing some things together and the backticks were necessary. I still habitually do certain redundant/needless things in scripts, but there's always room to improve.
# 11  
Old 07-06-2012
thank you all for the advice. I'll do some performance analysis over a period of time and post my results here.

Thanks
# 12  
Old 07-06-2012
@zer0sig, the behavior with pipes is unspecified by POSIX, but in ksh "time" times the total time, and I think in bash it does also...
Code:
time sleep 1 | { read; sleep 1 ;} | { read; sleep 1 ;}

Last edited by Scrutinizer; 07-06-2012 at 11:16 AM..
 
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