This example shows a regexp that checks for both patterns.

use strict;
use warnings;

my $out = "Backup/backup.txt";
my $logfile="log.txt";

open LOG, "<$logfile" or die "Cannot open $logfile for read :$!";
open OUT, ">$out" or die "Cannot open $out for write :$!";

/\"_.*\"/ && print OUT $_ while( <LOG> );

close LOG;
close OUT;
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or if you mean only print what's between the delimiters:

/\"_(.*)\"/ && print OUT "$1\n" while ( <LOG> );
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