How to use fswatch and rsync to automatically sync directories?

Question

I'd like to automatically run a one way sync between two local directories using rsync. Meaning when a change is detected in a file of /dir1 or its subdirs, the following command should run:

rsync -rtuv /dir1 /dir2

How can I go about achieving this with fswatch?

Is it possible to supply arguments for rsync to only copy the actual files that were changed, as given by the fswatch events?

Answer 1

alias run_rsync='rsync -azP --exclude ".*/" --exclude ".*" --exclude "tmp/" ~/Documents/repos/my_repository username@host:~'
run_rsync; fswatch -o . | while read f; do run_rsync; done

Second line runs run_rsync once unconditionally and then - on each change in current directory (or specify exact path instead of .)

Rsync options:

• -a - stands for "archive" and syncs recursively and preserves symbolic links, special and device files, modification times, group, owner, and permissions.
• -z - compression
• -P - combines the flags --progress and --partial. The first of these gives you a progress bar for the transfers and the second allows you to resume interrupted transfers
• --exclude - excludes files by pattern

You will need fswatch:

brew install fswatch