93 lines
1.8 KiB
Plaintext
93 lines
1.8 KiB
Plaintext
|
.TH INTRO 3
|
||
|
|
.SH NAME
|
||
|
|
intro \- introduction to the Plan 9 devices
|
||
|
|
.SH DESCRIPTION
|
||
|
|
A Plan 9
|
||
|
|
.I device
|
||
|
|
implements a file tree for client processes.
|
||
|
|
A file name beginning with a pound sign, such as
|
||
|
|
.LR #c ,
|
||
|
|
names the root of a file tree implemented by
|
||
|
|
a particular
|
||
|
|
.IR "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
|
||
|
|
.IP
|
||
|
|
.EX
|
||
|
|
bind("#c", "/dev", MREPL)
|
||
|
|
.EE
|
||
|
|
.LP
|
||
|
|
an
|
||
|
|
.IR ls (1)
|
||
|
|
of
|
||
|
|
.B /dev
|
||
|
|
will list the files provided by the
|
||
|
|
.I console
|
||
|
|
device.
|
||
|
|
.PP
|
||
|
|
A kernel device driver is a
|
||
|
|
.I 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
|
||
|
|
.RI ( Nop ,
|
||
|
|
.IR Session ,
|
||
|
|
.IR Flush ,
|
||
|
|
and
|
||
|
|
.IR Error )
|
||
|
|
have no subroutine equivalents.
|
||
|
|
.PP
|
||
|
|
When a system call is passed a file name beginning with
|
||
|
|
.L "#"
|
||
|
|
it looks at the next character, and if that is a valid
|
||
|
|
.I device character
|
||
|
|
it performs an
|
||
|
|
.IR 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
|
||
|
|
.L "/"
|
||
|
|
or end of string, those characters are passed as parameter
|
||
|
|
.I aname
|
||
|
|
to the attach. For example,
|
||
|
|
.IP
|
||
|
|
.EX
|
||
|
|
#I2
|
||
|
|
.EE
|
||
|
|
.PP
|
||
|
|
identifies the number 2 IP protocol stack
|
||
|
|
(see
|
||
|
|
.IR ip (3)).
|
||
|
|
.PP
|
||
|
|
Each kernel device has a conventional place at which to be bound
|
||
|
|
to the name space.
|
||
|
|
The
|
||
|
|
.I SYNOPSIS
|
||
|
|
sections of the following pages includes a
|
||
|
|
.I bind
|
||
|
|
command to put the device in the conventional place.
|
||
|
|
Most of these binds are done automatically by
|
||
|
|
.IR init (8)
|
||
|
|
using
|
||
|
|
.B newns
|
||
|
|
(see
|
||
|
|
.IR auth (2))
|
||
|
|
on the file
|
||
|
|
.B /lib/namespace
|
||
|
|
(see
|
||
|
|
.IR namespace (6)).
|
||
|
|
When typed to
|
||
|
|
.IR rc (1),
|
||
|
|
the
|
||
|
|
.I bind
|
||
|
|
commands will need quotes to protect the
|
||
|
|
.B #
|
||
|
|
characters.
|
||
|
|
.SH SEE ALSO
|
||
|
|
.IR intro (5),
|
||
|
|
.IR intro (2)
|