If you have used LS under Linux, careful you will find that the directory has executable permissions! Such as:
DRWXRWXR-X CL cl 4096 September 25 14:22.
DRWXR-XR-X CL cl 4096 October 10 16:00. /
Drwxrwxr-x 5 CL cl 4096 September 10:58 algorithm/
Drwxrwxr-x 2 CL cl 4096 September 21:44 temp/
Why?? Check on the Internet to find that is the meaning:
The executable permission of the directory indicates whether you can execute commands under the directory. If the directory does not have the-X permission, you cannot execute any commands on the directory or even CD into the directory. even though the directory still has the-R Read permission (this place is prone to make mistakes, think that having Read permission can enter the directory to read the file under the directory).
If the directory has the-X permission but does not have the-r permission, the user can execute the command and the CD can enter the directory. However, because there is no Read permission to the directory, under the directory, even if the LS command can be executed, but still do not have permission to read the document under the directory.
Record it and deepen your memory!
The difference between directory Read permission and execute permission under Linux