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Full Discussion: Using perl to grep a list of patterns from an input file
Top Forums Shell Programming and Scripting Using perl to grep a list of patterns from an input file Post 302761291 by Corona688 on Friday 25th of January 2013 11:46:40 AM
Old 01-25-2013
If grep is running out of memory, you may need to rethink your strategy. Just how large is the pattern file?

Are duplicate results allowed? Are things allowed to appear in more than one list?

If the pattern file's gigantic, you might be in trouble. Otherwise I might try something like this:

Code:
awk 'NR==FNR { A[++L]=$1; print "#" $1 > $1; next }
        { for(N=1; N<=L; N++) if(index($0, A[N])) { print > A[N] ; T[N]++} }
        END {
                for(N=1; N<=L; N++)
                if(!T[N]) { close(A[N]); print "#"A[N]" NONE" >A[N] }
        }' listfile inputdata

This will create output files named cr, pl, etc which you can cat together later if you need to.
This User Gave Thanks to Corona688 For This Post:
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LEARN ABOUT CENTOS

perl::critic::policy::builtinfunctions::requireblockgrep

Perl::Critic::Policy::BuiltinFunctions::RequireBlockGrepUser Contributed Perl DocumentaPerl::Critic::Policy::BuiltinFunctions::RequireBlockGrep(3)

NAME

       Perl::Critic::Policy::BuiltinFunctions::RequireBlockGrep - Write "grep { $_ =~ /$pattern/ } @list" instead of "grep /$pattern/, @list".

AFFILIATION

       This Policy is part of the core Perl::Critic distribution.

DESCRIPTION

       The expression forms of "grep" and "map" are awkward and hard to read.  Use the block forms instead.

	   @matches = grep  /pattern/,	  @list;	#not ok
	   @matches = grep { /pattern/ }  @list;	#ok

	   @mapped = map  transform($_),    @list;	#not ok
	   @mapped = map { transform($_) }  @list;	#ok

CONFIGURATION

       This Policy is not configurable except for the standard options.

SEE ALSO

       Perl::Critic::Policy::BuiltinFunctions::ProhibitStringyEval

       Perl::Critic::Policy::BuiltinFunctions::RequireBlockMap

AUTHOR

       Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>

COPYRIGHT

       Copyright (c) 2005-2011 Imaginative Software Systems.  All rights reserved.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.  The full text of this license
       can be found in the LICENSE file included with this module.

perl v5.16.3							    2014-06-09	       Perl::Critic::Policy::BuiltinFunctions::RequireBlockGrep(3)
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