steve@skx:~$ ./bug.pl 
LINE: '1 1'
LINE: '2 2'
LINE: '3 3'
Use of uninitialized value in scalar chomp at ./bug.pl line 7, <DATA> line 5.
Use of uninitialized value in substitution (s///) at ./bug.pl line 8, <DATA> line 5.
Use of uninitialized value in concatenation (.) or string at ./bug.pl line 13, <DATA> line 5.
LINE: ''
LINE: '  4 4'
LINE: '5 5'
LINE: ''
steve@skx:~$ perl -v | grep perl,
This is perl, v5.8.8 built for i486-linux-gnu-thread-multi