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Full Discussion: egrep is very slow : How to improve performance
Top Forums Shell Programming and Scripting egrep is very slow : How to improve performance Post 302166538 by vino on Tuesday 12th of February 2008 05:50:26 AM
Old 02-12-2008
Quote:
Originally Posted by hidnana
I have uploaded the $key as a screenshot as I don't have the text version right now..., it's a big string concatenated by "|".

Can you pls. tell me which is better than egrep....
grep.. perl... sed...?
And why should egrep take around 50..60 seconds in an iteration ...?
And will splitting the ${PICKUP_DIR}/new_update file into multiple files and searching each file until a match is found, help in anyway...?
Are the keys separated by a '|' ? Or is the whole thing a key in itself ?

If the keys are separated by '|', then change the file such that each key is on a new line. Then
Code:
egrep -f key.txt ${PICKUP_DIR}/new_update

I dont know if you will have any advantage in splitting up the file.
 

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LEARN ABOUT DEBIAN

nngrab

NNGRAB(1)						      General Commands Manual							 NNGRAB(1)

NAME

       nngrab - news retrieval by keyword (nn)

SYNOPSIS

       nngrab [ -c ] keyword

DESCRIPTION

       nngrab  invokes	nn on all USENET articles whose subject (or keyword) field(s) contain an instance of keyword.  nngrab is a fast equivalent
       for:
	    nn -mxX -s/keyword all

       For example,
	    nngrab tesla
       will retrieve items concerning Nikola Tesla.

       Keyword case is ignored unless -c is specified, and the keyword can be a regular expressions (escaped to avoid conflicts with  the  shell).
       For example,
	    nngrab "n.*tesla"

       The range of search includes all newsgroups on the system, including ones which are unsubscribed.

FILES

       $db/subjects   subject database

SEE ALSO

       nn(1), nnspew(8), egrep(1)

NOTES

       nngrab  can be much faster than the equivalent command shown above, if the tertiary news subject database generated by the nnspew(8) daemon
       exists.	To enable the faster operation, nnspew must be executed regularly by cron.

       nngrab uses egrep(1) to scan the subject database, so if you are not running fast egrep (GNU-style) this is all for naught.

       nngrab will use a subject database generated by nnspew independent of its age.  Thus, if you stop running nnspew, remember  to  remove  the
       subjects file as well.

BUGS

       Under version 6.4 onwards, search of the "Keywords:" field is not supported.
       Search on name is not possible either.

AUTHOR

       James A. Woods, NASA Ames Research Center
       E-mail: jaw@ames.arc.nasa.gov

4th Berkeley Distribution					    Release 6.6 							 NNGRAB(1)
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