`multisort' is a small program designed to take multiple httpd
logfiles in the Common Log Format and merge them into a single log,
sorted by date, sent to standard output.

This is useful if you're running a single website on multiple hosts
and using round-robin DNS to do load distribution. With multisort, you
can take the various logfiles from each server and merge them into a
single file for analysis.

WWW: https://www.xach.com/multisort/