use Path::Class qw( dir );
my $srcdir = dir( '/var/local/some_dir' );
my $destdir = dir( '/backup/some_dir' );

$destdir->mkpath unless -d $destdir;

die "$srcdir does not exist" unless -d $srcdir;
die "$destdir does not exist" unless -d $destdir;

print "Beginning backup...\n";

while ( my $file = $srcdir->next ) {
    next if $file->is_dir;
    my $target = $destdir->file( $file->basename.".gz" );
    if ( $file->stat->mtime <= $target->stat->mtime ) {
        print "backup is more recent than original\n";
        next;
    }
    system( "gzip -c $file > $target" );
    if ( $? != 0 ) { die "Gzip failed" }
    print "$file archived in $destdir\n";
}