#!/usr/bin/perl --
##
##
##
## perltidy -olq  -csc -csci=3 -cscl="sub : BEGIN END if " -otr -opr -ce -nibc -i=4 -pt=0   "-nsak=*"
## perltidy -olq  -csc -csci=10 -cscl="sub : BEGIN END if " -otr -opr -ce -nibc -i=4 -pt=0   "-nsak=*"
#!/usr/bin/perl --
use strict;
use warnings;
use Path::Tiny qw/ path /;
use POSIX();
use autodie qw/ close /;

Main( @ARGV );
exit( 0 );

sub Main {
    my $date      = POSIX::strftime( '%Y-%m-%d', localtime );
    my $bak       = "$date.bak";
    my @xml_files = path( $directory )->children( qr/\.xml$/ );
    for my $file ( @xml_files ) {
        Diddle( $file, "$file-$bak" );
    }
} ## end sub Main

sub Diddle {
    my( $in, $bak ) = @_;
    
    path( $in )->move( $bak );
    
    my $infh  = path( $bak )->openr_raw;
    my $outfh = path( $in )->openrw_raw;
    
    while( <$infh> ) {
        s{&}{&amp;}g; ## will match more than what you want fix it
        s{&amp;amp;}{&amp;}g;
        s{\s>\s}{&gt;}g;
        s{\s<\s}{&lt;}g;
        print $outfh $_;
    }
    
    close $infh;
    close $outfh;
} ## end sub Diddle