console - Man Page

console [generic-args] [-aAfFsS] [-e esc] console
console [generic-args] [-iIuwWx] [console]
console [generic-args] [-hPqQrRV] [-[bB] message] [-d [user][@console]] [-t [user][@console] message] [-[zZ] cmd]

generic-args: [-7DEknUv] [-c cred] [-C config] [-M master] [-p port] [-l user]

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

In the first form above, console asks the user's password before granting interactive access to a console (on a non-trusted system), since such a session may provide single-user access. If the server's autocompletion feature is enabled, only as much of the console name as is required to identify it uniquely to the server is required.

For non-interactive options, console outputs only the requested information and exits.

Console knows only of a primary conserver host (see the -M option below), to which it initially connects. In a multi-server environment, the primary server may refer the client to a different server handling the requested console, or it will provide a list of all servers if required (as when console is invoked with the -r option). Console then opens connections to the appropriate server(s). It is not necessary for the user of console to know which server manages which consoles, as long as console knows a valid primary server and all available consoles are listed in the primary server's configuration file.

Options may be given as separate arguments (e.g., -v -w) or clustered (e.g., -vw). Options and their arguments may be separated by optional white space. Option arguments containing spaces or other characters special to the shell must be quoted.

-7

Strip the high bit off of all data received, whether from user input or from the server, before any processing occurs. Disallows escape sequence characters with the high bit set.

-a

Access a console with a two-way (read-write) connection (this is the default). The connection is dropped to spy mode if someone else is attached read-write.

-bmessage

Broadcast a message to all users connected to each server.

-Bmessage

Same as -b but just send a message to users on the primary server.

-ccred

Load an SSL certificate and key from the PEM encoded file cred.

-Cconfig

Use the per-user configuration file config.

-d

Disconnect the users specified by user@console. You may specify the target as user (disconnect the user, regardless of what console they are attached to), @console (disconnect all users attached to console), or user@console (disconnect the user attached to console).

-D

Enable debugging output.

-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”.

-E

If encryption has been built into the code (--with-openssl), encrypted client connections are, by default, a requirement. This option disables any attempt at creating an encrypted connection. If you'd like to use encrypted connections when your server supports it, but fallback to non-encrypted otherwise, the -U option is what you want.

-f

Same as -a except it will force any existing connection into spy mode.

-h

Display a brief help message.

-i

Display status information in a machine-parseable format (see below for the details).

-I

Same as -i but just acts on the primary server.

-k

Abort the connection if the console is not in the `up' state immediately upon connecting.

-luser

Set the login name used for authentication to user. By default, console uses $USER if its uid matches the user's real uid, or $LOGNAME if its uid matches the user's real uid, or else the name associated with the user's real uid.

-Mmaster

The console client program polls master as the primary server, rather than the default set at compile time (typically “console”). The default master may be changed at compile time using the --with-master option. If --with-uds is used to enable Unix domain sockets, however, this option points console to the directory which holds those sockets. The default master directory (“/tmp/conserver”) may be changed at compile time using the --with-uds option.

-n

Do not read the system-wide configuration file.

-pport

Set the port to connect to. This may be either a port number or a service name. The default port may be changed at compile time using the --with-port option. If the --with-uds option was used, this option is ignored.

-P

Display the pid of the master daemon process on each server.

-q

The console client connects to each server to request that the server daemon quit (shut down). The root password of the host(s) running conserver is required unless the local host is listed as “trusted” in the conserver.cf file; in that case, just press <return>.

-Q

Same as -q but just acts on the primary server.

-r

Display daemon versions. The console client connects to each server to request its version information.

-R

Same as -r but just acts on the primary server.

-s

Request a read-only (spy mode) connection. In this mode all the escape sequences (below) work, or report errors, but all other keyboard input is discarded.

-t

Send a text message to user@console. You may specify the target as user (send to user, regardless of what console they are attached to), @console (send to all users attached to console), or user@console (send to user attached to console).

-u

Show a list of all consoles with status (`up', `down', or `init') and attached users (user@host if attached read-write, `<spies>' if only users in spy mode, or `<none>').

-U

If encryption has been built into the code (--with-openssl), encrypted client connections are, by default, a requirement. This option allows the client to attempt an encrypted connection but fall back to a non-encrypted connection if the server doesn't support encryption. If the encryption handshake is failing, disabling encryption on the client with the -E option is probably what you want.

-v

Be more verbose when building the connection(s). Use this option in combination with any of `show' options (below) for added benefit.

-V

Output the version and settings of the console client program and then exit.

-w

Show a list of all who are currently connected to consoles, including the hostnames where the console connections originate and the idle times. This is useful to see if anybody is actively using the console system if it becomes necessary to shut down conserver.

-W

Same as -w but just acts on the primary server.

-x

Show a list of consoles and devices.

-zcmd

Sends a command (cmd) to each server and displays the result. The valid commands are:

bringup

Try to connect all consoles marked as down (this is equivalent to sending the server a SIGUSR1)

SIGUSR1

Same as bringup

help

Displays the help message

pid

Returns the pid of the server (this is equivalent to -P)

quit

Instructs the server to shut down (this is equivalent to -q or sending the server a SIGTERM)

SIGTERM

Same as quit

reconfig

Instructs the server to reload the configuration file, then perform the actions of reopen (this is equivalent to sending the server a SIGHUP)

SIGHUP

Same as reconfig

reopen

Instructs the server to reopen all logfiles, then perform the actions of bringup (this is equivalent to sending the server a SIGUSR2)

SIGUSR2

Same as reopen

version

Returns the version of the server (this is equivalent to -V)

-Zcmd

Same as -z but just sends cmd to the primary server.

The -A, -F, or -S options have the same effect as their lower-case variants. In addition, they each request the last 20 lines of the console output after making the connection (as if “^Ecr” were typed).

The -i, -u, -w, and -x options can be given a console name, which will limit their output to that console.

The -i option outputs status information regarding each console in 15 colon-separated fields.

name

The name of the console.

hostname,pid,socket

The hostname, pid, and socket number of the child process managing the console.

type

The type of console. Values will be a `/' for a local device, `|' for a command, `!' for a remote port, `%' for a Unix domain socket, and `#' for a noop console.

console-details

The details regarding the console. The values here (all comma-separated) depend on the type of the console. Local devices will have values of the device file, baud rate/parity, and file descriptor for the device. Commands will have values of the command, the command's pid, the pseudo-tty, and file descriptor for the pseudo-tty. Remote ports will have values of the remote hostname, remote port number, “raw” or “telnet” protocol, and file descriptor for the socket connection. Unix domain sockets will have the path to the socket and the file descriptor for the socket connection. Noop consoles will have nothing.

users-list

The details of each user connected to the console. The details for each user are an `@' separated list of `w', `r', or `s' (for read-write, read-only, or suspended), username, hostname the user is on, the user's idle time, and (for `r' and `s' users only) “rw” or “ro” (if the user wants read-write mode or not). Each user bundle is separated by commas.

state

The state of the console. Values with either be “up”, “down”, or “init”.

perm

This value will either be “rw” or “ro”. It will only be “ro” if the console is a local device (`/' type) and the permissions are such that the server can open the file for read, but not write.

logfile-details

The details regarding the logging for the console. The comma-separated values will be the logfile, “log” or “nolog” (if logging is on or not - toggled via “^EcL”), “act” or “noact” (if activity logging is enabled or not - the `a' timestamp option), the timestamp interval, and the file descriptor of the logfile.

break

The default break sequence used for the console.

reup

If the console is currently down and the automatic reconnection code is at work, it will have the value of “autoup”, otherwise it will be “noautoup”.

aliases

The console aliases are presented in a comma-separated list.

options

The active options for the console are presented in a comma-separated list.

initcmd

The initcmd configuration option for the console.

idletimeout

The idletimeout configuration option for the console.

idlestring

The idlestring configuration option for the console.

Console reads configuration information from the system-wide configuration file (console.cf), then the per-user configuration file (.consolerc), and then applies command-line arguments. Each configuration location can override the previous. The same happens when parsing an individual file - the later entries always override the earlier entries. Because of that, you should put “global” defaults first and more specific defaults second.

The configuration file is read using the same parser as conserver.cf(5), and you should check that manpage for parser details. Console recognizes the following configuration blocks.

config hostname|ipaddr

Define a configuration block for the client host named hostname or using the address ipaddr. If the value of “*” is used, the configuration block will be applied to all client hosts.

escape esc

Set the escape sequence (see the -e command-line flag).

master master

Set the default master to master (see the -M command-line flag).

playback num|""

Override the playback length for the p escape command to num lines (if the server supports it). Using the special value of “0” will cause the client to use the number of lines of the current terminal (if that can be determined). If the null string (“""”) is used, the playback length will not be overridden.

port port

Set the default port to port (see the -p command-line flag).

replay num|""

Override the replay length for the r escape command to num lines (if the server supports it). Using the special value of “0” will cause the client to use the number of lines of the current terminal (if that can be determined). If the null string (“""”) is used, the replay length will not be overridden.

sslcacertificatefile filename

Load the valid CA certificates for the SSL connection from the PEM encoded file.

sslcacertificatepath directory

Load the valid CA certificates for the SSL connection from the PEM encoded files in the directory.

sslcredentials filename

Set the SSL credentials file location (see the -c command-line flag).

sslenabled yes|true|on|no|false|off

Set whether or not encryption is attempted when talking to servers (see the -E command-line flag).

sslrequired yes|true|on|no|false|off

Set whether or not encryption is required when talking to servers (see the -U command-line flag).

striphigh yes|true|on|no|false|off

Set whether or not to strip the high bit off all data received (see the -7 command-line flag).

username user

Set the username passed to the server to user (see the -l command-line flag).

terminal type

Define a configuration block when using a terminal of type type. If the value of “*” is used, the configuration block will be applied to all terminal types.

attach string|""

Set a string to print when successfully attached to a console. Character substitions will be performed based on the attachsubst value and occur before interpretation of the special characters below. If the null string (“""”) is used, no string will be printed. string is a simple character string with the exception of `\' and `^':

\a

alert

\b

backspace

\f

form-feed

\n

newline

\r

carriage-return

\t

tab

\v

vertical-tab

\\

backslash

\^

circumflex

\ooo

octal representation of a character (where ooo is one to three octal digits)

\c

character c

^?

delete

^c

control character (c is “and”ed with 0x1f)

An interesting use of attach and attachsubst would be:

terminal xterm {
    attach "^[]0;conserver: U@C^G";
    attachsubst U=us,C=cs;
}

attachsubst c=t[n]f[,...]|""

Perform character substitutions on the attach value. A series of replacements can be defined by specifying a comma-separated list of c=t[n]f sequences where c is any printable character, t specifies the replacement value, n is a field length (optional), and f is the format string. t can be one of the characters below, catagorized as a string replacement or a numeric replacement, which dictates the use of the n and f fields.

String Replacement

u

username

c

console name

Numeric Replacement

none available (yet)

For string replacements, if the replacement isn't at least n characters, it will be padded with space characters on the left. f must be `s'. For numeric replacements, the value will be formatted to at least n characters, padded with 0s if n begins with a 0, and space characters otherwise. f must be either `d', `x' or `X', specifying a decimal, lower-case hexadecimal, or an uppercase hexadecimal conversion. If the null string (“""”) is used, no replacements will be done.

detach string|""

Set a string to print once detached from a console. Character substitions will be performed based on the detachsubst value. See the attach option for an explanation of string. If the null string (“""”) is used, no string will be printed.

detachsubst c=t[n]f[,...]|""

Perform character substitutions on the detach value. See the attachsubst option for an explanation of the format string.

A simple configuration to set a new default escape sequence and override the master location would be:

# override options for all hosts
config * {
    master localhost;
    escape ^Ee;
}
# set things more specific to host1
# note: if the entries were reversed, host1
# would also use localhost.
config host1 {
    master console1;
}

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). (The escape sequences are actually processed by the server; see the conserver(8) man page for more information.) Commands are:

.

disconnect

;

move to another console

a

attach read-write if nobody already is

b

send broadcast message to all users on this console

c

toggle flow control (don't do this)

d

down the current console

ecc

change the escape sequence to the next two characters

f

forcibly attach read-write

g

group info

i

information dump

L

toggle logging on/off

l?

list the break sequences available

l0

send the break sequence associated with this console

l1-9a-z

send the specific break sequence

m

display the "message of the day"

o

close (if open) and reopen the line (to clear errors (silo overflows)) and the log file

p

playback the last 60 lines of output

P

set number of playback lines

r

replay the last 20 lines of output

R

set number of replay lines

s

switch to spy mode (read only)

u

show status of hosts/users in this group

v

show the version of the group server

w

who is using this console

x

examine this group's devices and modes

z

suspend this connection

!

invoke task

|

attach a local command to the console

?

display list of commands

^M (return)

continue, ignore the escape sequence

^R (ctrl-R)

replay the last line only

\ooo

send character having octal code ooo (must specify three octal digits)

If any other character is hit after the escape sequence, all three characters will be discarded. Note that a line break or a down command can only be sent from a read-write connection. To send the escape sequence through the connection one must redefine the outer escape sequence, or use ^Ec\ooo to send the first escape character before typing the second character directly.

In the -u output, the login “<none>” indicates no one is viewing that console, and the login “<spies>” indicates that no one has a read-write connection (only read-only).

When running a local command via “^Ec|”, you can type `^C' to send the command a SIGHUP, `^\' to send the command a SIGKILL, and `o' to toggle the display of the console data.

console -u

Outputs something like:

dumb      up      <none>
expert    up      ksb@mentor
tyro      up      <spies>
mentor    up      <none>
sage      up      fine@cis

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

console -w

Outputs something like:

ksb@extra       attach  2days     expert
file@cis        attach  21:46     sage
dmr@alice       spy      0:04     tyro

The third column is the idle time of the user. Either hours:minutes or number of days is displayed.

console -e "^[1" lv426

Requests a connection to the host “lv426” with the escape characters set to “escape one”.

The following default file locations may be overridden at compile time or by the command-line options described above. Run console -V to see the defaults set at compile time.

/etc/console.cf

system-wide configuration file

$HOME/.consolerc

per-user configuration file

It is possible to create a loop of console connections, with ugly results. Never run console from within a console connection (unless you set each escape sequence differently).

The -i output can produce more than the stated number of fields of information if the user-provided information has embedded colons.

I'm sure there are more, I just don't know where they are. Please let me know if you find any.

Thomas A. Fine, Ohio State Computer Science
Kevin Braunsdorf, Purdue University Computing Center
Bryan Stansell, conserver.com

conserver.cf(5), conserver.passwd(5), conserver(8)

bundle(1), conserver(8), conserver.cf(5), conserver.passwd(5).