How to write all foldernames in a directory to a file (using ls and sed)

I want to write all (and only) folder names in a directory to an empty file called ‘foldernames.txt’.

First thing to tackle would be how to list only folders but no files. While you can achieve this with

ls -l | grep "^d"

it makes you rely on the -l flag and gives you the long output with all the meta infos. You can actually do this without using grep by typing

ls -d  */

which will list you everyting ending on /. To get rid of that character too, pipe the list to the sed command

sed "s/\///"

to replace the forward slash. If you want a comma instead, adjust it to the following:

sed "s/\//,/"

To write to a file, you have to add > foldernames.txt . Puttin it all together:

ls -d  */ | sed "s/\///" > foldernames.txt