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Top Forums UNIX for Dummies Questions & Answers Join? Post 302922348 by Aia on Thursday 23rd of October 2014 09:49:36 PM
Old 10-23-2014
Quote:
Originally Posted by pc2001
Thanks Aia!

It would be great if you could elaborate a bit on the structure and syntax of the code!
FNR==NR : FNR and NR are built-in management variables in awk. FNR keeps a tally of the records read from the current file, NR keeps a tally of every record so far read from any files given.
If FNR is equal to NR, then we are dealing with the first file, in this case file2 and it execute the following part:
{a[$1$2]++; next} : That creates an array named a, which index is the combination of fields 1 and 2 and then skip to next line. This will happen only with first file given as argument

{if (! a[$1$2])print} : When the program gets here, it is dealing with the second file, and if it has not seen fields 1 and 2 before, it displays it.
This User Gave Thanks to Aia For This Post:
pc2001
 

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LEARN ABOUT MOJAVE

file::spec::cygwin5.18

File::Spec::Cygwin(3pm) 				 Perl Programmers Reference Guide				   File::Spec::Cygwin(3pm)

NAME

       File::Spec::Cygwin - methods for Cygwin file specs

SYNOPSIS

	require File::Spec::Cygwin; # Done internally by File::Spec if needed

DESCRIPTION

       See File::Spec and File::Spec::Unix.  This package overrides the implementation of these methods, not the semantics.

       This module is still in beta.  Cygwin-knowledgeable folks are invited to offer patches and suggestions.

       canonpath
	   Any "" (backslashes) are converted to "/" (forward slashes), and then File::Spec::Unix canonpath() is called on the result.

       file_name_is_absolute
	   True is returned if the file name begins with "drive_letter:", and if not, File::Spec::Unix file_name_is_absolute() is called.

       tmpdir (override)
	   Returns a string representation of the first existing directory from the following list:

	       $ENV{TMPDIR}
	       /tmp
	       $ENV{'TMP'}
	       $ENV{'TEMP'}
	       C:/temp

	   Since Perl 5.8.0, if running under taint mode, and if the environment variables are tainted, they are not used.

       case_tolerant
	   Override Unix. Cygwin case-tolerance depends on managed mount settings and as with MsWin32 on GetVolumeInformation() $ouFsFlags ==
	   FS_CASE_SENSITIVE, indicating the case significance when comparing file specifications.  Default: 1

COPYRIGHT

       Copyright (c) 2004,2007 by the Perl 5 Porters.  All rights reserved.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.18.2							    2014-01-06						   File::Spec::Cygwin(3pm)
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