Select Record based on First Column Post: 302126937

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Top Forums Shell Programming and Scripting Select Record based on First Column Post 302126937 by Shell_Life on Saturday 14th of July 2007 09:01:37 AM

07-14-2007

Registered User

Quote:

Originally Posted by matrixmadhan

Why do you need egrep when only a single pattern is specified in the regex ? Smilie

Matrixmadhan,
Thanks for verifying my solution.
You are right about it -- for this specific case, I don't really need 'egrep'.

Matrix, I have a habit of always use 'egrep' no matter what.

This comes from the fact that I have had problems trying to use some full
regular expressions with 'grep' -- I had to specify the '-E' option.

Sometimes I found that out after a long headache.

From my last disaster, I promise myself to never use 'grep' again, always 'egrep'.

Matrix, also to reinforce my idea, all three versions of 'grep' in my system all have the same hardlink:

Code:

>ls -li grep egrep fgrep
329785 -r-xr-xr-x  7 root  bin  22.1K Apr 12 09:11 egrep
329785 -r-xr-xr-x  7 root  bin  22.1K Apr 12 09:11 fgrep
329785 -r-xr-xr-x  7 root  bin  22.1K Apr 12 09:11 grep

Which leads me to believe that they are all the same program.

Hope to have answered your question.

Cheers. Smilie

Shell_Life

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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  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  zgrep  is invoked as zegrep or zfgrep then egrep or fgrep is used instead of grep.  If the GREP environment variable is set, zgrep uses
       it as the grep program to be invoked. For example:

	   for sh:  GREP=fgrep	zgrep string files
	   for csh: (setenv GREP fgrep; zgrep string files)

AUTHOR

       Charles Levert (charles@comm.polymtl.ca)

SEE ALSO

       grep(1), egrep(1), fgrep(1), zdiff(1), zmore(1), znew(1), zforce(1), gzip(1), gzexe(1)

																	  ZGREP(1)