Finding empty directories UNIX

Question

I need to find empty directories for a given list of directories. Some directories have directories inside it.

If inside directories are also empty I can say main di

Answer 1

Just find empty dirs

In order to just find empty directories (as specified in the question title), the mosg's answer is correct:

find -type d -empty

But -empty may not be available on very old find versions (this is the case of HP-UX for example). If this is your case, see the techniques described in below section Is a directory empty?.

Delete empty dirs

This is a bit tricky: Suppose a directory MyDir contains empty directories. After removing these empty directories, MyDir will become an empty directory and should also be removed. Therefore I use the command rmdir with the option --parents (or -p) that also removes parent directories when possible:

find -type d -empty -exec rmdir -vp --ignore-fail-on-non-empty {} +

On older find version the statement + is not yet supported, therefore you may use ; instead:

find -type d -empty -exec rmdir -vp --ignore-fail-on-non-empty {} `;`

Is a directory empty?

Most of these answers explain how to check if a directory is empty. Therefore I provide here the three different techniques I know:

1. [ $(find your/dir -prune -empty) = your/dir ]

   d=your/dir
   if [ x$(find "$d" -prune -empty) = x"$d" ]
   then
     echo "empty (directory or file)"
   else
     echo "contains files (or does not exist)"
   fi
   

   a variation:

   d=your/dir
   if [ x$(find "$d" -prune -empty -type d) = x"$d" ]
   then
     echo "empty directory"
   else
     echo "contains files (or does not exist or is not a directory)"
   fi
   

   Explanation:

   • find -prune is similar than find -maxdepth 0 using less characters
   • find -type d prints directories only

   • find -empty prints the empty directories and files

     > mkdir -v empty1 empty2 not_empty
     mkdir: created directory 'empty1'
     mkdir: created directory 'empty2'
     mkdir: created directory 'not_empty'
     > touch not_empty/file
     > find empty1 empty2 not_empty -prune -empty
     empty1
     empty2
     

2. (( ${#files} ))

   This trick is 100% bash but invokes (spawns) a sub-shell. The idea is from Bruno De Fraine and improved by teambob's comment. I advice this one if you use bash and if your script does not have to be portable.

   files=$(shopt -s nullglob dotglob; echo your/dir/*)
   if (( ${#files} ))
   then 
     echo "contains files"
   else 
     echo "empty (or does not exist or is a file)"
   fi
   

   Note: no difference between an empty directory and a non-existing one (and even when the provided path is a file).

3. [ $(ls -A your/dir) ]

   This trick is inspired from nixCraft's article posted in 2007. Andrew Taylor answered in 2008 and gr8can8dian in 2011.

   if [ "$(ls -A your/dir)" ]
   then
     echo "contains files"
   else
     echo "empty (or does not exist or is a file)"
   fi
   

   or the one-line bashism version:

   [[ "$(ls -A your/dir)" ]] && echo "contains files" || echo "empty or ..."
   

   Note: ls returns $?=2 when the directory does not exist. But no difference between a file and an empty directory.