# set xmllint to use a tab over 2 spaces
$ENV{XMLLINT_INDENT} = "\t";
# create (gag) a system call to call 
# xmllint and then move the temp file 
# to the target file
my $syscall = 'xmllint --format '.$outfile.' > '.$outfile.'-lint;mv '.$outfile.'-lint '.$outfile;
# ensure the temp file does not exist.
unlink("$outfile-lint");
	
system($syscall);