rsync is a very powerful program, but it contains a maze of twisty little options, all different, and sometimes I find I've messed things up long after it happened. I'm writing down typical incantations here.

Cloning file systems

• Use . (directory), not * to avoid file names starting with - from confusing rsync.
• Don't use the source directory name or it will (probably) be included in the destination, putting everything one level deeper.
• H preserves links; otherwise it would make a copy for every name a file has.
• a is the “archive” mode that does all sorts of things.
• v is verbose, so I can see what is happening.
• x sticks to current file system.

Don't use -L here; it will create additional files from symlinks.

I still have great difficulty deciding where rsync puts the files. It's far too easy for it to put them one level deeper in the hierarchy than intended. That's the reason for referring to the source directory as . (dot) rather than by name.

Backing up file systems

rsync -Havx --delete-after /src/$i $dumpfs/$me-$os

Until September 2024 I didn't include the H option, but it seems wrong not to.

This is effectively the same as cloning, except that files that have disappeared in the source file system are removed from the destination file system.

Backing up video

rsync > /tmp/rsyncerrs -LHav --partial --delete-after /spool/Already /spool/Docco destination
# or
cd /teevee/spool
# don't try to sync .snap or ..sujournal
rsync -LHav --partial --delete-after * /spool | tee /tmp/rsyncerrs