mknod, mkfifo - make a special file

     #include <sys/types.h>
     #include <unistd.h>
     #include <sys/stat.h>

     int mknod(const char *path, mode_t mode, dev_t dev)
     int mkfifo(const char *path, mode_t mode)

     Mknod creates a new file whose name is path. The mode  of  the  new  file
     (including  special  file  bits)  is initialized from mode, as defined in
     <sys/stat.h>.  (The protection part  of  the  mode  is  modified  by  the
     process's  mode  mask (see umask(2))).  The first block pointer of the i-
     node is initialized from dev and is used  to  specify  which  device  the
     special file refers to.

     If mode indicates a block or character special file, dev  is  the  device
     number  of  a  character  or block I/O device.  The low eight bits of the
     device number hold the minor device number that selects  a  device  among
     the  devices  governed by the same driver.  The driver is selected by the
     major device number, the next eight bits of the device number.

     If mode does not indicate a block special or  character  special  device,
     dev is ignored.  (For example, when creating a ``fifo'' special file.)

     Mknod may be invoked only by the super-user, unless it is being  used  to
     create a fifo.

     The call mkfifo(path, mode) is equivalent to

          mknod(path, (mode & 0777) | S_IFIFO, 0)

     Upon successful completion a value of 0 is returned.  Otherwise, a  value
     of -1 is returned and errno is set to indicate the error.

     Mknod will fail and the file mode will be unchanged if:

     [ENOTDIR]      A component of the path prefix is not a directory.

     [ENAMETOOLONG] The path name exceeds PATH_MAX characters.

     [ENOENT]       A component of the path prefix does not exist.

     [EACCES]       Search permission is denied for a component  of  the  path

     [ELOOP]        Too many symbolic links were  encountered  in  translating
                    the pathname.  (Minix-vmd)

     [EPERM]        The process's effective user ID is not super-user.

     [EIO]          An I/O error occurred while making the directory entry  or
                    allocating the inode.

     [ENOSPC]       The directory in which the entry for the new node is being
                    placed  cannot  be extended because there is no space left
                    on the file system containing the directory.

     [ENOSPC]       There are no free inodes on the file system on  which  the
                    node is being created.

     [EROFS]        The named file resides on a read-only file system.

     [EEXIST]       The named file exists.

     [EFAULT]       Path points outside the process's allocated address space.

     chmod(2), stat(2), umask(2).