Sorry, couldn’t help it.
More to the point, what the hell does 755 mean when referring to file permissions? You may remember, way back in my first post, that I talked about the output of
ls -l showing you the permissions for files. Well, that chain of permissions,
rwxrwxrwx can be represented quite simply octal notation. Why octal? Because each permission can be represented as a single bit, each group of permissions is three-bits, an octal number is three bits, and, as far as I can tell, our UNIX fore-bearers liked to make things confusing and intimidating for non-users. So there.
Therefore, if we go back to 755, we can convert each digit to binary, giving us
111 101 101 which tells us that the permissions for a file with the mode of 755 is
rwx for its owner,
r-x for its group, and
r-x again for all others.