Is there a man page for the file permission numbers?

I'm specifically talking about

r = 4

w = 2

x = 1

I can never remember them and I have to google it every time I need to set permissions besides 755. I don't think I'm alone, either, since there's even a site that calculates the number for you.

I just realized the man page for chmod doesn't have any description of the numbers and I can't figure out what other page would have them. I guess an info page would work as well, since apparently it comes pre-installed (I have arch; I'd have thought I'd have had to install that one myself--apparently not). It would be a lot easier for me if I could just refer to an 'on-line' man page (I use 'on-line' in the sense used in man man).

man chmod is likely to give you the command line tool. This may include some text that is easy to miss

The second digit selects permissions for the user who owns the file: read (4), write (2), and execute (1)

If you do man 2 chmod then you get the system call that actually does the work. This is harder to read, but does include the magic numbers:

   S_IRUSR  (00400)  read by owner

   S_IWUSR  (00200)  write by owner

   S_IXUSR  (00100)  execute/search  by owner ("search" applies for direc-

                     tories, and means that entries within  the  directory

                     can be accessed)

   S_IRGRP  (00040)  read by group

   S_IWGRP  (00020)  write by group

   S_IXGRP  (00010)  execute/search by group

   S_IROTH  (00004)  read by others

   S_IWOTH  (00002)  write by others

   S_IXOTH  (00001)  execute/search by others

It also provides some other magic values:

   S_ISUID  (04000)  set-user-ID  (set  process  effective  user   ID   on

                     execve(2))



   S_ISGID  (02000)  set-group-ID  (set  process  effective  group  ID  on

                     execve(2);  mandatory  locking,   as   described   in

                     fcntl(2);  take a new file's group from parent direc-

                     tory, as described in chown(2) and mkdir(2))



   S_ISVTX  (01000)  sticky bit (restricted deletion flag, as described in

                     unlink(2))

If you have Gnu chmod, then you can do it symbolically, e.g. chmod u+rw,g+r «file-name»

Gnu chmod is available on most Gnu/Linux systems, and can be installed on other systems.