dd lets you specify an offset to start reading the file at, with `skip`. This would let you perform a binary search by picking an offset in the file, reading a

dd lets you specify an offset to start reading the file at, with `skip`. This would let you perform a binary search by picking an offset in the file, reading a small chunk (say, a kilobyte), and scanning for the date/time string within it. Each read should be O(1) in terms of the size of the file, so a O(log(n)) for the binary search, whereas a grep-based approach is O(n). (The datetime in the log message is presumably sorted, or nearly so).