rsync: unrecognized option `--append-verify' on macOS (built-in openrsync) when resuming a partial download
rsync: unrecognized option `--append-verify'
Use plain --append and verify the result yourself with a checksum, then rename:
rsync -a --partial --append -e "ssh -o ConnectTimeout=20" host:/path/pack.zip ./pack.zip.part \
&& a=$(ssh host 'md5sum /path/pack.zip' | cut -d' ' -f1) \
&& b=$(md5 -q pack.zip.part) \
&& [ "$a" = "$b" ] && mv pack.zip.part pack.zip
Alternatively install GNU rsync (brew install rsync) and call /opt/homebrew/bin/rsync explicitly when you need --append-verify.
Symptom
Resuming an interrupted 141 MB download with the usual GNU rsync idiom fails immediately on a recent Mac:
rsync -a --partial --append-verify -e ssh host:/path/pack.zip ./pack.zip.part
rsync: unrecognized option `--append-verify'
usage: rsync [-0468BCDEFHIKLOPRSTWVabcdghiklnopqrtuvxyz] ...
Cause
Recent macOS ships openrsync as /usr/bin/rsync instead of Samba rsync 2.6.9. It accepts --append, --partial, --inplace etc., but not --append-verify (and other GNU-rsync-3.x-only flags). Scripts written for Linux break silently in background jobs because the command just exits 1.
Verify
The resumed copy continued from 113 MB to the full 141,111,245 bytes and both md5 sums matched (3b7ad719... 3b7ad719...).
Notes
--append trusts the existing prefix; always checksum afterwards, especially if the partial file was written to a flaky external disk.
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