Top Forums Shell Programming and Scripting awk variables in regex expression ? Post 302518335 by uran101 on Friday 29th of April 2011 10:16:46 AM
Quote:
Originally Posted by michaelrozar17
Code:
x=/jon/
echo jon | awk -v xa=$x '$1~/'"$xa"'/ {print}'

I have a question about something similar.

Code:
awk ' 
BEGIN { split(" ' " ` date ` " ' ", date) } 
$1 == date[2] && $2 == date[3] {print $0}
' $1

Why are there two pairs of quotes? I would say that there is one pair of double quotes too many, but when I remove them, it produces an error (different, depending on which pair I remove).

P.S. The script is meant to be a calendar reminder. There is an additional text file. It contains something like the following text:

Code:
Sep 30  mother's birthday
Oct  1  lunch with joe, noon
Oct  1  meeting 4pm

 
Test Your Knowledge in Computers #274
Difficulty: Easy
OpenSolaris is a descendant of the UNIX System V Release 4 (SVR4) code base developed by Sun and AT&T in the late 1980s.
True or False?

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English(3pm)						 Perl Programmers Reference Guide					      English(3pm)

NAME
English - use nice English (or awk) names for ugly punctuation variables SYNOPSIS
use English; use English qw( -no_match_vars ) ; # Avoids regex performance penalty # in perl 5.16 and earlier ... if ($ERRNO =~ /denied/) { ... } DESCRIPTION
This module provides aliases for the built-in variables whose names no one seems to like to read. Variables with side-effects which get triggered just by accessing them (like $0) will still be affected. For those variables that have an awk version, both long and short English alternatives are provided. For example, the $/ variable can be referred to either $RS or $INPUT_RECORD_SEPARATOR if you are using the English module. See perlvar for a complete list of these. PERFORMANCE
NOTE: This was fixed in perl 5.20. Mentioning these three variables no longer makes a speed difference. This section still applies if your code is to run on perl 5.18 or earlier. This module can provoke sizeable inefficiencies for regular expressions, due to unfortunate implementation details. If performance matters in your application and you don't need $PREMATCH, $MATCH, or $POSTMATCH, try doing use English qw( -no_match_vars ) ; . It is especially important to do this in modules to avoid penalizing all applications which use them. perl v5.18.2 2014-01-06 English(3pm)

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