linux - How to implement commands that are not available to non-root users

Question

Obviously not allowed

Today when I was reading a book, I suddenly discovered that the permission of chmod is 755, but ordinary users still cannot use it. Why is this?
I originally thought the permission was 700 or 744, but the result was 755. Question. . . I googled but couldn't find the answer, please give me some advice

Answer 1

Simply put, the two permissions (whether the user can execute the program file) and (whether the process can execute specific instructions) are separate.

You already have the former permission. The error message you see is because the process you opened does not have the latter permission.

Answer 2

Chmod permissions indicate that ordinary users can use this command, but /tmp permission modification requires superuser permissions

sudo chmod 777 /tmp # Generally, the /tmp folder permissions are not modified