local $\ = '';
    my $filename = "/mydir/myfile";
    open FILE, "<$filename"
        or die "Cannot open $filename for reading\n";
    my $file = <FILE>;
    close FILE;

    $file =~ s/\t/\\t/g;

    open FILE, ">$outfilename"
        or die "Cannot open $outfilename for writing\n";
    print FILE $file;
    close FILE;