What to do to make loop ignore empty directories - bash

Question

I have a loop and I need it to ignore empty directories.
for i in */*/
do
cd "$i"
mv ./*.py ..
cd -
rm -r "$i"
done
What can i add on to make it ignore empty directories?
I have this but I would like something simpler
x=$(shopt -s nullglob dotglob; echo "$i"/*)
(( ${#x} )) || continue

Answer 1

What can i add on to make it ignore empty directories?
Bash does not have a primitive operator for testing whether a directory is empty. The best alternative in your case is probably to test whether pathname expansion matches any files within. That's what you are already considering, though I would write it differently.
As a general rule, I would also avoid changing the working directory. If you must change directory then consider doing it in a subshell, so that you need only let the subshell terminate to revert to the original working directory. Using a subshell is also a good approach when different parts of your script want different shell options.
I would probably write your script like this:
#!/bin/bash
shopt -s nullglob dotglob
for i in */*/; do
anyfiles=( "$i"/* )
if [[ ${#anyfiles[#]} -ne 0 ]]; then
# Process nonempty directory "$i"
# If there are any Python files within then move them to the parent directory
pyfiles=( "$i"/*.py )
if [[ ${#pyfiles[#]} -ne 0 ]]; then
mv "${pyfiles[#]}" "$(dirname "$i")"
fi
# Remove directory "$i" and any remaining contents
rm -r "$i"
fi
done
If you want that as part of a larger script, then you could put everything from the shopt to the end in a subshell to limit the scope of the shopt.
Alternatively, you could simplify that slightly at the cost of some clarity by using loops to skip the capture of the directory contents into explicit variables:
#!/bin/bash
shopt -s nullglob dotglob
for i in */*/; do
for anyfile in "$i"/*; do
# Process nonempty directory "$i"
# If there are any Python files within then move them to the parent directory
for pyfile in "$i"/*.py; do
mv "$i"/*.py "$(dirname "$i")"
break
done
# Remove directory "$i" and any remaining contents
rm -r "$i"
break
done
done
In that case, each inner loop contains an unconditional break at the end, so at most one iteration will be performed.