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Well, i'd use a classic state machine for this problem, then we can work line-by-line, without having to load the whole file into memory.

#!/usr/bin/env perl use strict; use warnings; use diagnostics; my @blocklines; my $inblock = 0; open(my $IFH, '<', 'blockextract.txt') or die($!); while((my $line = <$IFH>)) { chomp $line; if($line =~ /parameters\ after\ change/) { # Start of a block we want to read $inblock = 1; next; } # Skip handling line unless we are in a block next unless($inblock); if($line =~ /NRG\ location/) { # Block ends here # Do whatever you want to do to the block lines # stored in @blocklines. # I'm just dumping them to STDOUT print "*** START ***\n"; print join("\n", @blocklines), "\n"; print "*** END ***\n\n"; # Clean up block @blocklines = (); $inblock = 0; next; } # just some line within the interesting block # remember it for later in @blocklines push @blocklines, $line; next; } close $IFH; exit(0);

That way, we can even modify the program very slightly to make it work via pipes, working live on a stream of data generated by some other program. We just remove the open and close calls and change the while loop a bit:

while((my $line = <>)) {

Then we can use the program on an arbitrary stream of this kind of data, and it extracts each block as soon as it is pushed into the programs STDIN:

cat blockextract.txt | perl

And the only thing the state machine has to hold in memory is the block it is currently working on and a single state variable...

perl -e 'use MIME::Base64; print decode_base64("4pmsIE5ldmVyIGdvbm5hIGdpdmUgeW91IHVwCiAgTmV2ZXIgZ29ubmEgbGV0IHlvdSBkb3duLi4uIOKZqwo=");'

In reply to Re: Extract Block Of Text From Log by cavac
in thread Extract Block Of Text From Log by ImJustAFriend

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