`sed 's/^ \{2,\}//' -i filename.html`;

##</code><code>##

system('sed','s/^ \{2,\}//', '-i', 'filename.html') == 0
    or die "Couldn't launch sed: $! / $?";

##</code><code>##

use Tie::File;
my $filename = 'filename.html';

tie @file, 'Tie::File', $filename 
    or die "Couldn't open '$filename': $!";
for (@file) {
    s/^ {2}//;
};