Linux Questions

I want to sync retroarch save files across devices on my local network using a bash script. Plan is to run the script as a cronjob to keep all machines synced.

This does the trick as a one-off in the terminal: rsync -a /home/localuser/.config/retroarch/states/ remoteuser@192.168.1.12:/home/remoteuser/.config/retroarch/states/

• Copies new save files to remote location
• Updates any save files which were modified

But when I put the same line in a bash script rsync's behavior changes. My bash script looks like this:

#!/usr/bin/env bash
rsync -a /home/localuser/.config/retroarch/states/ remoteuser@192.168.1.12:/home/remoteuser/.config/retroarch/states/

I call it with bash sync_saves.sh

• Copies new save files to remote location
• ~~Updates any save files which were modified~~

Strangely, rsync doesn't update modified files when run as a script. But it's not failing altogether, because it transfers new files OK. What am I missing?

Update: if I do the rsync in the reverse order (remote machine -> local machine) then the bash script works as expected. So my issue exists only when rsync goes local machine -> remote machine. Why would this matter?

Update 2 (Solution): I changed the command to rsync -razu /home/localuser/.config/retroarch/states/ remoteuser@192.168.1.12:/home/remoteuser/.config/retroarch/states/, but I'm not sure that made any impact. The issue was how I was doing my testing. I was doing touch testfile.txt to change the modification date on a file & then I'd try to transfer it with the bash script & watch the modification date on the downstream machine as confirmation that it moved correctly. Problem is that rsync must be smart & doesn't transfer a file if only the modification date changes. It requires the contents to also change. Whenever I tested this way I would never see the file transfer, but when I changed my testing method to change the contents of the file instead (not just the modification timestamp) then all worked fine!

I feel like a dummy for initially mixing testing methods & coming to the wrong conclusion about what was happening, but happy it's working now & maybe I learned a lesson!