mknod name b | c major minor
mknod name p
mknod name m
mknod name s
In the first case, name is the special file to be created. The second argument is either b to indicate a block-type special file or c to indicate a character-type. The last two arguments are numbers specifying the major and minor device numbers; these may be either decimal or octal [see mknod(2) for information on minor device number values]. The assignment of major device numbers is specific to each system. You must be the super-user to use this form of the command.
The second case, p, is used to create a FIFO (named pipe).
The third case, m, is used to create XENIX shared memory handles.
The fourth case, s, is used to create XENIX semaphore handles.