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Top Forums Shell Programming and Scripting Understanding regex behaviour when using quantifiers Post 302750267 by DGPickett on Monday 31st of December 2012 09:56:37 AM
Old 12-31-2012
This is shorter: Regular expression - Wikipedia, the free encyclopedia

QED went to MULTICS, probably before UNIX, and became qedx, which is very close to ed and ex. Later, Waterloo ported it to FRED.

grep -E is essentially egrep is ERE.
 

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XZGREP(1)							     XZ Utils								 XZGREP(1)

NAME
xzgrep - search compressed files for a regular expression SYNOPSIS
xzgrep [grep_options] [-e] pattern file... xzegrep ... xzfgrep ... lzgrep ... lzegrep ... lzfgrep ... DESCRIPTION
xzgrep invokes grep(1) on files which may be either uncompressed or compressed with xz(1), lzma(1), gzip(1), or bzip2(1). All options specified are passed directly to grep(1). If no file is specified, then the standard input is decompressed if necessary and fed to grep(1). When reading from standard input, gzip(1) and bzip2(1) compressed files are not supported. If xzgrep is invoked as xzegrep or xzfgrep then egrep(1) or fgrep(1) is used instead of grep(1). The same applies to names lzgrep, lze- grep, and lzfgrep, which are provided for backward compatibility with LZMA Utils. ENVIRONMENT
GREP If the GREP environment variable is set, xzgrep uses it instead of grep(1), egrep(1), or fgrep(1). SEE ALSO
grep(1), xz(1), gzip(1), bzip2(1), zgrep(1) Tukaani 2009-07-05 XZGREP(1)
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