I like the solution in your first link, altough I would also add the update
"-u" flag to those commands to make sure that newer files (newer by
modification date) don't get overwritten by older files with the same name.
So, if you have source folders named folder_a and folder_b, and an empty
destination folder folder_c, then the following two commands will merge the
contents of folder_a and folder_b into folder_c:
rsync -auP folder_a/ folder_c/
rsync -auP folder_b/ folder_c/
The trailing slash after folder_a and folder_b is important, by the way. It
tells rsync to copy the contents of the directory instead of the directory
itself.
And it would probably be good to keep backups of the original folders, in
case you suddenly realize that you wanted to keep an older version of a file,
for example.
Maybe there is a way to do this with graphical tools, but I don't know any.
I've never used file managers like Gnome Commander or Double Commander.
