Is there a reason you are unable to write the file-in-memory to a temporary file-on-disk, then read that back in? Something like:

open my $TEMPF, '>', 'tempfile.tmp' or die("Unable to write to tempfil
+e");

print $TEMPF $file_contents;
close $TEMPF;

open my $TEMPF, '<', 'tempfile.tmp' or die("Can't read tempfile back i
+n");
while (chomp (my $line = <$TEMPF>)) {
   next unless $line =~ /^06/; #skip unneeded lines
   chomp(my $line2 = <$TEMPF>);
   #process lines
}
close $TEMPF;

unlink('tempfile.tmp');
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