I was downloading two files with curl, and the download was taking ages (average rate about 4K/s), so I used a curlrc which said "resume where you left off" so that when I shut down the computer and re-started curl the next day, it would continue the task (project total time: about eight hours for the first file).
When it finished the first file, it wanted to resume the second file, but it used the same offset as it had used for the first file! Let's say it had downloaded 90MB of 100MB, so when I started curl today, it said "please give me data starting from offset 90'000'000". When I finished the file, it said, "please give me the data for the second file, starting from offset 90'000'000"... but the second file wasn't that large!
I would have expected "-C -" to mean "resume where you left off on each file, determining the offset individually for each file". But no.
So I removed the "-C -" because otherwise it wouldn't download the second file... and clobbered the first one because it decided to re-download from the beginning. *§$(§8.