> And also Ævar is right. The original just has a format-patch output > in $_ and prints it to the output stream in one go. Sorry but I misread the patch. By dropping the $/ = undef, it wants to read from $fd (which is "format-patch --stdout" output) one line at a time. So unless a line has two addresses, this would "work" as intended. Again, as I said, I do not agree with the definition of "work" here, though ;-).