Find unix command gives “Not a directory” error message

Question

To locate files on my computer that have a given string, I execute the following command in the root directory using a Unix bash shell:

bash$ sudo find . -name file-name-to-be-searched

I then get a list of files but also the following:

find: ./dev/fd/3: Not a directory
find: ./dev/fd/4: Not a directory

This is puzzling because there is also ./dev/fd/5 which does not appear listed and for all three of them, when I do:

bash$ cd ./dev/fd
bash$ cat 3 

(or 4 or 5)

I get:

Bad file descriptor

Bash gives the same message with:

bash$ cd 3

This is the contents of the directory:

bash$ pwd
/dev/fd
bash$ ls -l
total 0
crw--w----  1 bro   tty     16,   5 Oct 26 02:54 0
crw--w----  1 bro   tty     16,   5 Oct 26 02:54 1
crw--w----  1 bro   tty     16,   5 Oct 26 02:54 2
dr--r--r--  1 root  wheel         0 Oct 21 09:15 3
dr--r--r--  1 root  wheel         0 Oct 21 09:15 4
dr--r--r--  1 root  wheel         0 Oct 21 09:15 5

I would like to know why I get this behavior, why I don't see a similar message for file ./dev/fd/5 and if this may be an indicator that I am not searching the entire directory structure. If there is some sort of corrupted file that this signals, is there a way not to list it?

Answer 1

To address the last part of the question, as suggested by Marc 's comment (thank you,), adding 2> /dev/null gets rid of the error messages:

bash$ sudo find. -name file-name-to-be-searched 2> /dev/null

However, it leaves us a bit in the dark as to why there is no error message for the file descriptor /dev/fd/5 and its possible impacts in the execution of find .