Ruby: how do I recursively find and remove empty directories? - ruby

Question

I'm trying to write some ruby that would recursively search a given directory for all empty child directories and remove them.
Thoughts?
Note: I'd like a script version if possible. This is both a practical need and a something to help me learn.

Answer 1

In ruby:
Dir['**/*'] \
.select { |d| File.directory? d } \
.select { |d| (Dir.entries(d) - %w[ . .. ]).empty? } \
.each { |d| Dir.rmdir d }

Answer 2

Looking at the examples from kch, dB. and Vishnu above, I've put together a one-liner that I think is a more elegant solution:
Dir['**/'].reverse_each { |d| Dir.rmdir d if Dir.entries(d).size == 2 }
I use '**/' instead of '/**/*' for the glob, which only returns directories, so I don't have to test whether it's a directory later. I'm using reverse_each instead of sort.reverse.each as it's shorter and supposedly more efficient, according to this post. I prefer Dir.entries(d).size == 2 to (Dir.entries(d) - %w[ . .. ]).empty? because it's a little easier to read and understand, although (Dir.entries(d) - %w[ . .. ]).empty? would probably work better if you had to run your script on Windows.
I've tested this quite a bit on Mac OS X and it works well, even with recursive empty directories.

Answer 3

You have to delete in reverse order, otherwise if you have an empty directory foo with a subdirectory bar you will delete bar, but not foo.
Dir.glob(dir + "/**/*").select { |d|
File.directory?(d)
}.reverse_each { |d|
if ((Dir.entries(d) - %w[ . .. ]).empty?)
Dir.rmdir(d)
end
}

Answer 4

Why not just use shell?
find . -type d -empty -exec rmdir '{}' \;
Does exactly what you want.

Answer 5

Dir['/Users/path/Movies/incompleteAnime/foom/**/*']. \
select { |d| File.directory? d }. \
sort.reverse. \
each {|d| Dir.rmdir(d) if Dir.entries(d).size == 2}
just like the first example, but the first example doesn't seem to handle the recursive bit. The sort and reverse ensures we deal with the most nested directories first.
I suppose sort.reverse could be written as sort {|a,b| b <=> a} for efficiency

Answer 6

I've tested this script on OS X, but if you are on Windows, you'll need to make changes.
You can find the files in a directory, including hidden files, with Dir#entries.
This code will delete directories which become empty once you've deleted any sub-directories.
def entries(dir)
Dir.entries(dir) - [".", ".."]
end
def recursively_delete_empty(dir)
subdirs = entries(dir).map { |f| File.join(dir, f) }.select { |f| File.directory? f }
subdirs.each do |subdir|
recursively_delete_empty subdir
end
if entries(dir).empty?
puts "deleting #{dir}"
Dir.rmdir dir
end
end

Answer 7

Dir.glob('**/*').each do |dir|
begin
Dir.rmdir dir if File.directory?(dir)
# rescue # this can be dangereous unless used cautiously
rescue Errno::ENOTEMPTY
end
end

Answer 8

module MyExtensions
module FileUtils
# Gracefully delete dirs that are empty (or contain empty children).
def rmdir_empty(*dirs)
dirs.each do |dir|
begin
ndel = Dir.glob("#{dir}/**/", File::FNM_DOTMATCH).count do |d|
begin; Dir.rmdir d; rescue SystemCallError; end
end
end while ndel > 0
end
end
end
module ::FileUtils
extend FileUtils
end
end

Answer 9

For a pure shell solution, I found this very useful
find "$dir" -depth -type d |
while read sub; do
[ "`cd "$sub"; echo .* * ?`" = ". .. * ?" ] || continue
echo rmdir "$sub"
#rmdir "$sub"
done
But if you have gnu-find installed (not universal yet)...
find . -depth -type d -empty -printf "rmdir %p\n"
this uses find with xargs...
find . -depth -type d -print0 |
xargs -0n1 sh -c '[ "`cd "$0"; echo .* * ?`" = ". .. * ?" ] &&
echo "rmdir $0";'