jcfilesize

I once wanted to find out how big a block device was, and I knew of no better way to do it than to try and read from different places and note where I get read errors. I still don't know a better way, but I have automated the process. jcfilesize is a small program that reads from exponentially larger positions in a file until the end is found, and then does a binary search to find the exact position of the end and prints the size using several notations.

Instead of searching for the end, it can find the place where the file begins or stops to contain only zeroes, which has proven useful to get status reports when filling a partition with zeros or random data, or to find out how much of a partition that has been used by a filesystem.

This is jcfilesize version 0.5.
Usage: jcfilesize filename ["zeros"|"notzeros" [blocksize]]