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Full Discussion: grep - speed of search
Top Forums UNIX for Dummies Questions & Answers grep - speed of search Post 28835 by davirime on Wednesday 25th of September 2002 08:26:29 AM
Old 09-25-2002
grep - speed of search

I grepped for a string from a directory of very large files. This took quite a long time (not a problem). When I grepped for a different string from the same files immediately after, the output was MUCH quicker.

My question is, does anybody know why the second grep was so much quicker than the first? Is indexing used?

Any responses would be most welcome, thankyou.
 

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GZGREP(1)						      General Commands Manual							 GZGREP(1)

NAME
gzgrep, gzegrep, gzfgrep - search possibly compressed files for a regular expression SYNOPSIS
gzgrep [ grep_options ] [ -e ] pattern filename... DESCRIPTION
gzgrep is used to invoke the grep on compress'ed or gzip'ed files. All options specified are passed directly to grep. If no file is speci- fied, then the standard input is decompressed if necessary and fed to grep. Otherwise the given files are uncompressed if necessary and fed to grep. If gzgrep is invoked as gzegrep or gzfgrep then egrep or fgrep is used instead of grep. If the GREP environment variable is set, gzgrep uses it as the grep program to be invoked. For example: for sh: GREP=fgrep gzgrep string files for csh: (setenv GREP fgrep; gzgrep string files) AUTHOR
Charles Levert (charles@comm.polymtl.ca) SEE ALSO
grep(1), egrep(1), fgrep(1), gzdiff(1), gzmore(1), gznew(1), gzforce(1), gzip(1), gzexe(1) ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +--------------------+-----------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +--------------------+-----------------+ |Availability | SUNWgzip | +--------------------+-----------------+ |Interface Stability | External | +--------------------+-----------------+ NOTES
Source for gzip is available in the SUNWgzipS package. GZGREP(1)
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