Bash: for each directory

Question

I am working on a script that needs to perform an action in every sub-directory of a specific folder.

What is the most efficient way to write that?

Answer 1

find . -type d -print0 | xargs -0 -n 1 my_command

Answer 2

for D in `find . -type d`
do
    //Do whatever you need with D
done

Answer 3

A version that avoids creating a sub-process:

for D in *; do
    if [ -d "${D}"]; do
        echo "${D}"   # your processing here
    fi
done

Or if your command is a single command this is more concise:

for D in *; do [ -d "${D}"] && my_command; done

Or an even more concise version (thanks @enzotib). Note that in this version each value of D will have a trailing slash:

for D in */; do my_command; done

Answer 4

the accepted answer will break on white spaces if the directory names have them, and the preferred syntax is $() for bash/ksh. Use GNU find -exec option with +; eg

find .... -exec mycommand +; #this is same as passing to xargs

or use a while loop

find .... |  while read -r D
do
  ...
done 

Answer 5

This will create a subshell (which means that variable values will be lost when the while loop exits):

find . -type d | while read -r dir
do
    something
done

This won't:

while read -r dir
do
    something
done < <(find . -type d)

Either one will work if there are spaces in directory names.