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Manual Reference Pages  -  CONSOLE (8)


console - console server client program




console [-a|A | -f|F | -s|S] [-rv] [-e attn] [-M master] machine
console -u|U|w|W|x|X [-v] [-M master]
console -q|Q [-v] [-M master]
console -d|D|p|P [-v] [-M master]
console -Y [-v]
console -h
console -V


Console is used to manipulate console terminals remotely or poll running conserver(8L) daemons for status information.

Console queries the user for an access password before granting interactive access to a console (on a non-trusted system) since such a session may provide single-user access. This password may be the superuser’s password or a password installed for a limitted number of devices.

Any default (-a) connection is dropped to spy mode if someone else is attached read-write. Force this spy mode connection to read write with the ‘‘f’’ command below.

In the non-interactive mode console exits after it outputs the requested information.


-a Access a console with a two-way connection (this is the default). The uppercase varient (-A) of this option forces a replay command into the negotiated connection after it is established.
-d Display daemon versions. The console client connects to each server to request its version information. The uppercase varient (-D) of this option only requests only the primary server’s version.
-eesc Set the initial two character escape sequence to those represented by esc. Any of the forms output by cat(1)’s -v option are accepted. The default value is ‘‘^Ec’’ (control-e lowercase-c) read as ‘‘escape conserver’’.
-f Same as -a except it will force any existing read/write connection into spy mode. Uppercase (viz. -F) forces a replay command.
-h Display a brief help message.
  The console client program polls master as the primary server, rather than the hard coded default (‘‘localhost’’).
-p The console client program polls all each peer console servers for their process id. The uppercase varient (-P) of this option only polls the master console server.
-q The console client requests the server daemon quit (shutdown). A password is sent in the protocol stream, if none is required for the local host to shutdown the server just press return. The uppercase varient (-Q) of this option just acts on the master server.
-r Request a raw connection to the group control virtual console, this is only useful for learning the protocol used by the non-interactive sequences. If you think this is something you might want to try you need to get out a little more.
-s Requests a read-only (spy mode) connection. If this mode all the escape sequences (below) work, or report errors, but all other keyboard input is discarded. Uppercase (viz. -S) still forces a replay command.
-u The console client program polls each console group for a list of connected users. Uppercase (viz. -U) limits the scan to groups of the master server.
-V Output the version of the console client program.
-v Be more verbose during when building the connection(s). Use this option in combination with any of ‘show’ options (below) for added benefit.
-w Show a list of all connections to all consoles. Uppercase (viz. -W) limits the scan to groups of the master server.
-x Show a list of consoles and devices. Uppercase (viz. -X) limits the scan to groups of the master server.
-Y Send a restart signal to the console server on the local host. This doesn’t work across the network as it reads the process id from the network and sends the signal with kill(2).


The connection can be controlled by a two character escape sequence, followed by a command. The default escape sequence is ‘‘control-E c’’ (octal 005 143). Commands are:

aswitch to attach mode
ctoggle flow control (don’t do this)
ddown the current console
echange the escape sequence to the next two characters
fforce a switch to attach mode
l1send a 3 second serial line break (might halt a Sun)
oreopen the line to clear errors (silo overflows)
rreplay the last 20 lines of output
sswitch to spy mode
ushow other users on this port
vshow the version of the group server
wwho is using this console
xexamine this group’s devices and modes.
zsuspend this connection
?display list of commands
^Itoggle tab expansion
^Jcontinue, ignore the escape sequence
^Pchat with the power controller
^Rreplay the last line only
;provide a new login or shift to a new console
+(-)be more (less) free with newlines

If any other character is hit after the escape sequence, all three characters will be discarded. Note that serial line breaks, line down, and power controller commands can only be sent from a full two-way attachment. To send the escape sequence through the connection one must redefine the outer escape sequence.

In the -u output, the login <none> indicates no one is viewing that console, the login <spies> indicates that no one has a full two-way attachment. When no one is attached to a console its output is cloned to the stdout of the server process.


console -u
  Outputs something like:


The <none> indicates no one is viewing dumb or mentor, the <spies> indicates only read-only connections exist for tyro, other login@host entries are the currently attached sage and expert.

console -w
  Outputs something like:

ksb@extraon expertFri Feb 15 16:40:36 1991
file@cison sageThu Feb 14 1:04:10 1991
dmr@alicespy tyroThu Feb 7 10:09:59 1991

console -e “^[1” lv426
  Requests a connection to the host ‘‘lv426’’ with the escape characters set to ‘‘escape one’’.


Connections suspended under Dynix sometimes break the kernel when resumed. Suspended connections are a poor idea in general, just disconnect instead.

It is possible to create a loop of console connections, with ugly results. Never run console from within a console connection. In root’s .profile set $CONSOLE with:

         CONSOLE="-- hey ’do not run console from here’"

The -r option doesn’t really help to explain how connections get built.


Thomas A. Fine, Ohio State Computer Science.
Kevin Braunsdorf, Federal Express (

SEE ALSO, conserver(8L), autologin(8L), kill(2)
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