README.md

Estimate the number of lines in a large file

Get the size of the file:

$ wc -c myfile.jsons
104431233268 myfile.jsons

Then pipe it through head to take only e.g. 1/1000th of the file:

cat myfile.jsons | head -c 104431233 | wc -l
213657

Our file should then have 213657*1000 = 213,657,000 lines.

Of course, it only works if the length of your lines is uniform.