Re^5: What does ">>" do? (And other stat questions)

[Laurent_R]

The file mode given by stat[2] consists of two distinct pieces of information: the file type and the file permissions. If you want to see only the permissions, you have to mask off the file type portion of the mode. This is what the bitwise and (&) with 07777 does, as shown in my previous post.

The file type corresponds to the first character displayed on a ls -l command under the Unix shell prompt:

$ ls -l /etc/passwd
-rw-r--r-- 1 Laurent root 841  9 mai   23:24 /etc/passwd

The initial dash (-) displayed above says it is a regular file, a d would indicate a directory, a l a symbolic link, an s a socket, etc. This information is the file type displayed in the first half byte (four bits) of the file mode reported by stat[2].

[three18ti]

Ah Ha!

So cool! Thanks for the explanation

So following that logic, could we then mask off the first four bits with 077777?

but that would only be 15 bits, not 16, so probably not.

(Side note, I thought there were 8 bits to a byte?)

[Laurent_R]

Of course you are right, a byte is (usually) 8 bits, I meant to say the first half byte, but my fingers did not obey my mind. I made the correction in my post.