rsync tips

rsync tips.txt

rsync -av -@-1 as the baseline thing
or with --delete to remove things from DEST, and probably
--delete-excluded when using --exclude
rsync -@-1 compares timestamps by nanoseconds instead of seconds, which is important for transferring e.g. PostgreSQL data; rsync doesn't read the data inside each file if the (mtime, size) matches on both ends, unless you:
rsync -c
rsync -X to also copy xattrs (slower)
rsync -H for hard link preservation (uses memory to track all the inodes)
rsync -S to preserve sparseness in sparse file
rsync --zc=zstd
rsync --zc=zstd --compress-level=6  or maybe 8 where the link is slow and extra compression is useful
rsync --progress
rsync --dry-run
rsync --remove-source-files, in the rare cases you want that
rsync --append when transferring only append-only logs
rsync --inplace if you need to be able to resume unfinished transfers; also generally faster with many files, avoiding renames
rsync --delete-before when copying to a DEST that might run out of space if the deletes aren't done first
rsync -e "ssh -o ..." if you need to control SSH stuff, like
rsync -e "ssh -o Compression=no" which may increase throughput with data that doesn't compress
rsync --bwlimit=RATE
rsync --chmod=u+w, to make writable read-only files in e.g. `.git/`

It doesn't have good built-in parallelism, but you can do e.g.
```
rsync -a SRC1 DEST1 &
rsync -a SRC2 DEST2 &
wait
```
A trailing slash on SRC e.g. SRC/ puts SRC/* rather than SRC into DEST.

The path in rsync user@host:path starts in HOME.

With unstable SRC data, rsync twice or thrice or until it doesn't find any more changes.

Browsers and Electron things should probably be closed before rsync'ing their profiles.