Modified file on the robot is not overwritten by make upload

[stephane-caron]

After editing a file directly on the robot (e.g. via SSH to the onboard Raspberry Pi), the file does not get updated by subsequent make upload from the dev machine. Why is that so and how to overwrite the remote file with the source one?

[stephane-caron]

Using make upload to upload a consistent build to the robot will in turn call rsync:

rsync -Lrtu ... <LOCAL_REPOSITORY>/ <REMOTE_REPOSITORY>/

A particularity of rsync is that a remote file will only be updated if the local file is more recent. Otherwise, the remote file (that is, on the robot) is assumed more up-to-date, and left as is.

Consider the following scenario:

1. Prepare a configuration file, let's call it config.gin, in the local (dev) repository
2. Run make upload
3. Edit the remote config.gin on the robot, change some parameters
4. Modify the code in the dev repository (not the config)
5. Run make upload again

In this case, the make upload from step 5 will not overwrite the remote config.gin from step 3 with the local one. However, if we do:

6. Modify the local config.gin
7. Run make upload

Then the changes to config.gin from step 3 will be lost and the new version from step 6 will be written to the robot.