How to delete subfolders having only files of a specific extension

Question

I want to delete subfolders, only if all its files are of some specific extension, say json. I have seen a similar question Find and copy directories containing file type. Thanks in advance.

├── 20101018_DSC05369.JPG
├── f
│   └── some.jpg
├── f1
│   ├── f
│   │   └── some.json
│   ├── f4
│   │   ├── a.jpg
│   │   └── some.json
│   └── some.json
└── some.jpg


exp. result:
.
├── 20101018_DSC05369.JPG
├── f
│   └── some.jpg
├── f1
│   ├── f4
│   │   ├── a.jpg
│   │   └── some.json
│   └── some.json
└── some.jpg

Answer 1

#! /bin/bash
# recursively
shopt -s globstar || exit
# for every subfolder
for dir in **;do
      [[ ! -d $dir ]] && continue # if not directory then skip
      # SUBFOLDER name inspected
      echo "$dir"
      # count number of files in subfolder 
      NUMFILES=$(find "$dir" -type f | wc -l)
      # if non-empty folder
      if (( $(bc <<<"$NUMFILES > 0") )); then
      # if all files in folder have extension json, remove subfolder
              NUMJSON=$(find "$PWD/$dir" -iname '*.json' | wc -l)

              if (( $(bc <<<"$NUMFILES == $NUMJSON") )); then
                echo "rm -rf "$dir"" 
                rm -rf "$dir"
              fi
      fi
done

Answer 2

The following one liner will solve your problem:

sudo find . -links 2 -exec sh -c '[ "$(ls -l \{} | grep -c '^-')" \
-eq "$(ls \{} | grep -c '\.json$')" ]' \; -print0 | xargs -0  echo rm -rf {} + 2> /dev/null \;

Explanation of the code:

sudo find . -links 2 

In the current directory will only return leaf directories.

 ls -l \{} | grep -c '^-'

returns the number of regular files in the directory.

 ls \{} | grep -c '\.json$'

returns the number of files with json extension in the directory.

sh -c '[ "$(ls -l \{} | grep -c '^-')" -eq "$(ls \{} | grep -c '\.json$')" ]'

spwans a sub-shell that returns true if all files in the directry have json extension, thus allowing the instruction to proceed.

rm -rf {} + 2> /dev/null

will delete the non-empty directory redirecting standard error to /dev/null.

Caveat: This solution will delete found folders that do not contain any regular file.

Please backup your data before executing tests.

Execute the code in the top directory.

Remove echo when your tests succeed.