Question

Trying to debug an issue with a server and my only log file is a 20GB log file (with no timestamps even! Why do people use System.out.println() as logging? In production?!)

Using grep, I’ve found an area of the file that I’d like to take a look at, line 347340107.

Other than doing something like

head -<$LINENUM + 10> filename | tail -20  

… which would require head to read through the first 347 million lines of the log file, is there a quick and easy command that would dump lines 347340100 – 347340200 (for example) to the console?

update I totally forgot that grep can print the context around a match … this works well. Thanks!

Answer 1

with GNU-grep you could just say

grep --context=10 ...