I can copy a directory like so:
~$ cp -r ./Desktop/ /tmp/
Similarly, if I just wanted to copy the files from within a directory, I could do so:
~$ cp -r ./Desktop/. /tmp/
Things become a little more tricky if I want to copy the source directory into a target directory, that is a sub-directory of the source. i.e. copy a directory into itself. For example:
~$ cp -r ./Desktop/ ./Desktop/sub/
Would throw the following error: cp: cannot copy a directory, './Desktop/', into itself, './Desktop/sub/'
This can be circumnavigated, somewhat, using extglob, like so:
~$ cp -r ./Desktop/!(sub) ./Desktop/sub/
However, this last command is dependent on the directory sub already existing.
How can you copy a directory into itself, in such a fashion that the command to do so creates the sub directory at the same time?