$ perl foo.pl Use of uninitialized value $_ in scalar chomp at foo.pl line 5, line 1. INPUT LINE: 2.83506E+03 2.83697E+03 2.83911E+03 2835060 2836970 2839110 Use of uninitialized value $_ in scalar chomp at foo.pl line 5, line 2. INPUT LINE: 2.84117E+03 2.84331E+03 2.84544E+03 2841170 2843310 2845440 Use of uninitialized value $_ in scalar chomp at foo.pl line 5, line 3. INPUT LINE: 2.84750E+03 2.84958E+03 2.85172E+03 2847500 2849580 2851720 Use of uninitialized value $_ in scalar chomp at foo.pl line 5, line 4. INPUT LINE: 2.85383E+03 2.85588E+03 2.85804E+03 2853830 2855880 2858040 Use of uninitialized value $_ in scalar chomp at foo.pl line 5, line 5. INPUT LINE: 2.86012E+03 2860120