# execute the command and save results in a file handle to reduce memory usage
	if (($head =~ /.+/) && ($tail =~ /.+/)) {
		my @lastLines = ();
		my $length;
		open (my $fh, $vars{cmd} . " 2>&1|") or die;
		while (<$fh>) {
			#$logger->info($fh . " " . $_);
			if ($_ =~ /$tail/ims) { #found the last line, terminate loop, do not append the output
				$tailFound = 1;
				last;
			}
			
			if($headFound){ #the header line is already found and ignored, so safe to apprend output
				$output .= $_;
			}
			
			if (!$headFound and $_ =~ /$head/ims) { #next lines will be the matched output
				$headFound = 1;
			}
			
			#keeps track of the most recent N lines
			push(@lastLines, $_);
			my $length = @lastLines;
			if($length >= $vars{lastNLines}){
				shift(@lastLines);
			}
			
			#$output .= $_;
		}
		
		unless ($headFound && $tailFound) {
			$output = "\n\nCould not match command output. Printing the last $vars{lastNLines} lines:\n";
			$output .= join("", @lastLines);
		}
		close ($fh);
	} else {
		open (my $fh, $vars{cmd} . " 2>&1|") or die;
		while (<$fh>) {
			#$logger->info($fh . " " . $_);
			$output .= $_;
		}
		close ($fh);
	}