I was wondering if it would be possible to get a --resume flag into rsync, that mimics wget's -c flag. It's seriously non-obvious to try to figure out how to get rsync to resume nicely(--partial --no-whole-file, I *think*), and it's definitely needed over slowband connections when the carrier could drop at any time. Thanks!
Unfortunately, a --resume option wouldn't work because any data from a partial transfer would have been discarded before you tried to do the resume (and, interestingly, when you tell rsync to keep the partial data, it automatically resumes without needing an extra option). The best way to run rsync for a long transfer has been to specify the -P option (which turns on both --partial and --progress). The user does need to remember to use this on the initial transfer, though, or else there will be nothing to resume. You don't need to worry about --no-whole-file because it is only on by default for a local copy. Beginning with 2.6.3, there is an alternative: --inplace. This works very well for both copying a new file from scratch and (especially) for resuming a partial transfer of that new file (which avoids an extra temp-file copy being made when resuming). So, a good download-option combo is "-P --inplace" (which is the equivalent of the longer "--progress --inplace" because the --inplace option implies --partial). If you have an idea for how to make this easier for the user, feel free to tweak this suggestion.