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.TH CPU 1

.SH NAME

cpu \- connection to CPU server

.SH SYNOPSIS

.B cpu

[

.B -h

.I server

] [

.B -u

.I user

] [

.B -a

.I auth-method

] [

.B -P

.I patternfile

] [

.B -e

.I encryption-hash-algs

] [

.B -k

.I keypattern

] [

.B -c

.I cmd args ...

]

.PP

.B cpu

[

.B -R

|

.B -O

]

.SH DESCRIPTION

.I Cpu

starts an

.IR rc (1)

running on the

.I server

machine, or the machine named in the

.B $cpu

environment variable if there is no

.B -h

option.

.IR Rc 's

standard input, output, and error files will be

.B /dev/cons

in the name space where the

.I cpu

command was invoked.

Normally,

.I cpu

is run in an

.IR rio (1)

window on a terminal, so

.IR rc

output goes to that window, and input comes from the keyboard

when that window is current.

.IR Rc 's

current directory is

the working directory of the

.I cpu

command itself.

.PP

The name space for the new

.I rc

is an analogue of the name space where the

.I cpu

command was invoked:

it is the same except for architecture-dependent bindings such as

.B /bin

and the use of fast paths to file servers, if available.

.PP

If a

.B -u

argument is present,

.I cpu

uses the argument as the remote user id.

.PP

If a

.B -c

argument is present, the remainder of the command line is executed by

.I rc

on the server, and then

.I cpu

exits.

.PP

If a

.B -P

argument is present, the

.I patternfile

is passed to

.IR exportfs (4)

to control how much of the local name space will be exported to

the remote system.

.PP

The

.B -a

command allows the user to specify the authentication mechanism used

when connecting to the remote system.  The two possibilities for

.I auth-method

are:

.TF netkey

.TP

.B p9

This is the default.  Authentication is done using the standard Plan 9

mechanisms, (see

.IR authsrv (6)).

No user interaction is required.

.TP

.B netkey

Authentication is done using challenge/response and a hand held

authenticator or the

.I netkey

program

(see

.IR passwd (1)).

The user must encrypt the challenge and type the encryption

back to

.IR cpu .

This is used if the local host is in a different protection domain than

the server or if the user wants to log into the server as a different

user.

.PD

.PP

The

.B -e

option specifies an encryption and/or hash algorithm to

use for the connection.  If both are specified, they must

be space separated and comprise a single argument, so they

must be quoted if in a shell command.  The default is

.L rc4_256

encryption and

.L sha1

hashing.  See

.IR ssl (3)

for details on possible algorithms.  The argument

.L clear

specifies no encryption algorithm and can be used to talk

to older versions of the

.I cpu

service.

.PP

The

.B -k

flag specifies a key pattern to use to restrict the keys

selected by the

.I auth_proxy

call used for authentication.

.PP

The name space is built by running

.B /usr/$user/lib/profile

with the root of the invoking name space bound to

.BR /mnt/term .

The

.B service

environment variable is set to

.BR cpu ;

the

.B cputype

and

.B objtype

environment variables reflect the server's architecture.

.PP

The

.B -R

flag causes

.I cpu

to run the server (remote) side of the protocol.

It is run from service files such as

.BR /bin/service/tcp17010 .

The

.B -O

flag is similar but simulates the pre-9P2000 version

of the 

.I cpu

protocol.

.SH FILES

The name space of the terminal side of the

.I cpu

command is mounted, via

.IR exportfs (4),

on the CPU side on directory

.BR /mnt/term .

The files such as

.B /dev/cons

are bound to their standard locations from there.

.SH SOURCE

.B /sys/src/cmd/cpu.c

.SH SEE ALSO

.IR rc (1) ,

.IR rio (1) ,

.IR exportfs (4)

.SH BUGS

Binds and mounts done after the terminal

.B lib/profile

is run are not reflected in the new name space.

.PP

When using the

.B -a

option to `log in' as another user, be aware that

resources in the local name space will be made

available to that user.