linux mkdir function can't authorize full permission

Question

I am testing the mkdir function to create a new directory:

folder =  mkdir(\"./linux\", 511);

or

 folder = mk         


        

Answer 1

Check the umask function: man 2 umask

Answer 2

From man 2 mkdir:

The argument mode specifies the permissions to use. It is modified by the process's umask in the usual way: the permissions of the created directory are (mode & ~umask & 0777).

I suggest you look at your umask - it is probably set to 0022. Try a chmod post-mkdir.

Answer 3

Permissions set by system calls like mkdir and open are always masked against the current process's umask. You can change the current umask using the umask() function; make sure to set it back when you're done.