06-07-2011
grep first occurrence but continue to next entry in patternfile
I have 1300 files (SearchFiles0001.txt, SearchFiles0002.txt, etc.) , each with 650,000 lines, tab-delimited data.
I have a pattern file, with about 1000 lines with a single word. Each single word is found in the 1300 files once.
If I grep -f PatternFile.txt SearchFiles*.txt >OutputFile.txt
the search takes forever, because it searches 650,000 lines x 1300 files for each of the 1000 words.
If I grep -f PatternFile.txt -m 1 SearchFiles*.txt >OutputFile.txt
the search stops after the first line of PatternFile.txt, and I get an OutputFile.txt with 1300 lines: the first entry of PatternFile.txt, but none of the other 999.
How do I make the search faster (by finding the first occurrence of my search parameter, and then moving on to the next search parameter in PatternFile.txt)?
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LEARN ABOUT NETBSD
zfgrep
ZGREP(1) BSD General Commands Manual ZGREP(1)
NAME
zgrep, zegrep, zfgrep -- print lines matching a pattern in gzip-compressed files
SYNOPSIS
zgrep [grep-flags] [--] pattern [files ...]
zegrep [grep-flags] [--] pattern [file ...]
zfgrep [grep-flags] [--] pattern [file ...]
DESCRIPTION
zgrep runs grep(1) on files or stdin, if no files argument is given, after decompressing them with zcat(1).
The grep-flags and pattern arguments are passed on to grep(1). If an -e flag is found in the grep-flags, zgrep will not look for a pattern
argument.
zegrep calls egrep(1), while zfgrep calls fgrep(1).
EXIT STATUS
In case of missing arguments or missing pattern, 1 will be returned, otherwise 0.
SEE ALSO
egrep(1), fgrep(1), grep(1), gzip(1), zcat(1)
AUTHORS
Thomas Klausner <wiz@NetBSD.org>
BSD
December 28, 2003 BSD