I use rsync for backups, site deployments, and other purposes where I need to sync two folders. It took a little while to figure out, but has been great for those purposes since. Every once in a while, though, I run into issues with it. Recently, I set up an rsync script to back up most of the files on my entire computer. Since this takes a while and the computer is actively running during the backup, things can change while it is still running. This can lead to some errors like “rsync warning: some files vanished before they could be transferred”. Even though this is a warning, and the sync works perfectly fine, it returns a non-zero exit code. This caused my script to stop and thus the rest of the backup activity didn’t finish.
I looked for an option or simple solution to allow it to go on without complaining. There is no option to the command, but there is an official solution to the problem, a series of bash commands to trap that particular exit code. To make it easier to use in my script, I turned it into a function, which looks like:
_sync() {
set -o pipefail
local prefix=''
if [ -x "$(command -v caffeinate)" ]; then
prefix='caffeinate'
fi
$prefix rsync "${@}" 2>&1 | (egrep -v "^(file has vanished: |rsync warning: some files vanished before they could be transferred)" || true)
local r=$?
if [[ $r == 24 ]]; then
r=0
fi
return $r
}
and can be used in place of rsync anywhere after it’s defined in the script. This might look like:
_sync -av --delete --link-dest='../_latest' sourcePath desetPath
My new Mac (2020 Macbook Air) kept sleeping the disk or something when I left it to go by itself during the sync. Macs have the caffeinate command to prevent the computer from going into various or any sleep states. Putting it before rsync ensured that it continued running without interruption from sleep.
This worked just fine for my backup script.