`rsync`: trailing slash vs wildcard

Question

Suppose I want to sync the contents of a directory (source_dir) using rsync without creating a directory named source_dir in the target directory.

I can do this using rsync source_dir/ target_dir or rsync source_dir/* target_dir.

Is the following correct? The former will sync everything, including hidden files and source_dir/.. Using the latter the shell will expand the * to every every non-hidden file in source_dir and thus every non-hidden file in source_dir will be synced.

(I'm asking mainly to check my understanding, but the XY problem behind this is that rsync -t source_dir/ target_dir tries to set the time and I want to avoid that without using -O.)

Answer 1

You are correct.

If you're using a shell such as bash you can tell it to have * match on dot files as well as usual ones:

shopt -s dotglob
rsync -rt source_dir/* target_dir/

I've added a trailing slash to the target so that it's always considered as a directory - even if the wildcard expands only to a single item. At the other end of the scale, you may encounter problems with the shell enumerating the results if * matches a (very) large number of files.

Possibly a better solution would be use find to generate the set of files, having it exclude the root of the directory tree:

find source_dir -mindepth 1 -print0 |
    rsync -t --files-from=- --from0 . target-dir/

(If source_dir is an absolute path then replace the . with /.)