For multiple files (grep -F is the same as fgrep, you should use one of these)
This runs five searches at a time in parallel. So it is approximately 5 times faster than a single thread of grep, on modern multi-core cpus.
Hi Jim,
Am I correct in assuming that you intended to have an & after backup.txt in this for loop?
Should the number of grep's to be run in parallel be tied to the number of CPU cores available to the process, or is grep I/O limited?
---------------------------
Added later: Are you sure that the output from grep is line-buffered? If not you could end up with output with parts of lines intermixed by running multiple greps writing to a single output file!
Last edited by Don Cragun; 02-02-2013 at 05:03 AM..
Reason: Additional question...
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... (1 Reply)
Hi,
Is mv (move) command quicker than cp (copy command)?
I have large files and I want to know if mv actually copy the data to a new file then deletes the old or whether it just alters information the file system without physically moving data - Unfortuanately I don't have large files to test... (2 Replies)
Hello,
I have a Supermicro server with a P4SCI mother board running Debian Sarge 3.1. This is the "dmidecode" output related to RAM info:
RAM speed information is incomplete.. "Current Speed: Unknown", is there anyway/soft to get the speed of installed RAM modules? thanks!!
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#declare variables to be used.
help=-1
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I have a script that processes a fair amount of data -- say, 25-50 megs per run. I'd like ideas on speeding it up. The code is actually just a preprocessor -- I'm using another language to do the heavy lifting. But as it happens, the preprocessing takes much more time than the final processing... (3 Replies)
I analysed disk performance with blktrace and get some data:
read:
8,3 4 2141 2.882115217 3342 Q R 195732187 + 32
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hi
i'm greping the files with sepefic keyword, where the file is of too big. Assume there are 10 days log file each of more than 200mb. i've to grep all those files with a specific keywords.
for example,
1. i'll grep for error message
2. after the i'll do one more grep for keyword... (4 Replies)
I've got at least 30,000 XML files that I'm using the grep command to get their filename. Can I use the head command to grab just the beginning 8 lines and compare that instead of parsing the whole document? It would speed things up! or maybe grep -m? (49 Replies)
Discussion started by: emc^24sho
49 Replies
LEARN ABOUT HPUX
zgrep
ZGREP(1) General Commands Manual ZGREP(1)NAME
zgrep - search possibly compressed files for a regular expression
SYNOPSIS
zgrep [ grep_options ] [ -e ] pattern filename...
DESCRIPTION
Zgrep invokes grep on compressed or gzipped files. These grep options will cause zgrep to terminate with an error code:
(-[drRzZ]|--di*|--exc*|--inc*|--rec*|--nu*). All other options specified are passed directly to grep. If no file is specified, 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 the GREP environment variable is set, zgrep uses it as the grep program to be invoked.
EXIT CODE
2 - An option that is not supported was specified.
AUTHOR
Charles Levert (charles@comm.polymtl.ca)
SEE ALSO grep(1), gzexe(1), gzip(1), zdiff(1), zforce(1), zmore(1), znew(1)ZGREP(1)