INTRO(3)						     Library Functions Manual							  INTRO(3)

NAME

       intro - introduction to the Plan 9 devices

DESCRIPTION

       A  Plan	9  device  implements a file tree for client processes.  A file name beginning with a pound sign, such as names the root of a file
       tree implemented by a particular kernel device driver identified by the character after the pound sign.	Such names are	usually  bound	to
       conventional locations in the name space.  For example, after

	      bind("#c", "/dev", MREPL)

       an ls(1) of /dev will list the files provided by the console device.

       A kernel device driver is a server in the sense of the Plan 9 File Protocol, 9P (see Section 5), but with the messages implemented by local
       rather than remote procedure calls.  Also, several of the messages (Nop, Session, Flush, and Error) have no subroutine equivalents.

       When a system call is passed a file name beginning with it looks at the next character, and if that is a valid device character it performs
       an  attach(5)  on  the corresponding device to get a channel representing the root of that device's file tree.  If there are any characters
       after the device character but before the next or end of string, those characters are passed as parameter aname to the attach.	For  exam-
       ple,

	      #Itcp

       identifies the implementation of the TCP protocol supplied by the IP device (see ip(3)).

       Each  kernel device has a conventional place at which to be bound to the name space.  The SYNOPSIS sections of the following pages includes
       a shell bind command to put the device in the conventional place.  Most of these binds are done automatically by init(8).

SEE ALSO

       intro(5), intro(2)

																	  INTRO(3)