Using `find -perm` to search when permission is not set

Question

I want to find unreadable files in my directory (e.g. files with gr). So I tried this:

find . -perm -gr

Does he show me all the files? So I tried this:

find . -perm -g+r

And he showed me only readable files. It seems that -perm -gr matches all files. I am using CentOS 5.5. Am I doing something wrong? It doesn't look like -perm -gr does anything useful.

Answer 1

Try:

find . ! -perm -g+r

Answer 2

If you want to find files that are not readable to you , you can use

 find . ! -readable 

Answer 3

You could see all the files when executing the instruction below, because you ran it as root.

 find . -perm -gr 

Try a regular user.