How to recursively list all hidden files and directories

With zsh:

mv -- *(D) html

mv will complain that it can't move html to itself, but will still move the rest.

With bash:

shopt -s dotglob
mv -- * html

With ksh93:

FIGNORE='@(.|..)'
mv -- * html

POSIXly:

mv -- * .??* .[!.] html

or

mv -- * .[!.]* ..?* html

(you're likely to get errors for those of the patterns that have no match. That should be harmless but will still cause the exit status to be non-zero so in script you would not be able to distinguish that with a failure to move files).

With GNU tools:

for d in Dir*; do
  find "$d" -mindepth 1 -mtime -180 -print -quit | grep -q . ||
    echo rm -rf "$d"
done

Remove the echo when satisfied. Remove the -q to find out why a directory is not being removed.