I have a project folder which has messy permissions on all files. I've had the bad tendency of setting everything to octal permissions 777 because it solved all non security related issues. Then FTP uploads, files created by text editors etc. has their own set of permissions making everything a mess. I've decided to take myself together and start using the permissions the way they were meant to be used.

I figured 664 was a good default for all my files and folders, and I'd just remove permissions for others on private files, and add +x for executable files.

The second I changed my project folder to 664 however:

$ sudo chmod -R 664 .  
$ ls  
ls: cannot open directory .: Permission denied  

Which makes no sense to me. I have read/write permissions, and I'm the owner of the project folder. The leftmost part of ls -l in my project folder looks like this:

-rw-rw-r-- 1 codemonkey codemonkey ...
drw-rw-r-- 5 codemonkey codemonkey ...
-rw-rw-r-- 1 codemonkey codemonkey ...
-rw-rw-r-- 1 codemonkey codemonkey ...
drw-rw-r-- 3 codemonkey codemonkey ...
-rw-rw-r-- 1 codemonkey codemonkey ...
-rw-rw-r-- 1 codemonkey codemonkey ...
-rw-rw-r-- 1 codemonkey codemonkey ...
drw-rw-r-- 4 codemonkey codemonkey ...
drw-rw-r-- 5 codemonkey codemonkey ...

I assume this has something to do with the permissions on the directories, but what?