close OUTPUT                # wait for sort to finish
                    or warn $! ? "Error closing sort pipe: $!"
                               : "Exit status $? from sort";
##</code><code>##

$ perl -w net1.pl
Writing line 1
 Read_three,got This is line number 1

Writing line 2
 Read_three,got This is line number 2

Writing line 3
 Read_three,got This is line number 3

Writing line 4
 An error occured during writing :Broken pipe at net1.pl line 14.
Wrote 3 lines of text