Count the number of lines in a file without reading entire file into memory?

Question

I\'m processing huge data files (millions of lines each).

Before I start processing I\'d like to get a count of the number of lines in the file, so I can then indic

Answer 1

Same as DJ's answer, but giving the actual Ruby code:

count = %x{wc -l file_path}.split[0].to_i

The first part

wc -l file_path

Gives you

num_lines file_path

The split and to_i put that into a number.