Options:
TELNET
BINARY
option on both input and output.
USER
variable
of the
ENVIRON
option if supported by the remote system.
The name used is that of the current user as returned by
getlogin(2)
if it agrees with the current user ID,
otherwise it is the name associated with the user ID.
.telnetrc
file.
(See the
toggle skiprc
command on this man page.)
TRUE
.
ENVIRON
option, then
user
will be sent to the remote system as the value for the variable USER.
This option implies the
-a
option.
This option may also be used with the
open
command.
When in rlogin mode, a line of the form ~. disconnects from the remote host; ~ is the telnet escape character. Similarly, the line ~^Z suspends the telnet session. The line ~^] escapes to the normal telnet escape prompt.
Once a connection has been opened,
telnet
will attempt to enable the
TELNET
LINEMODE
option.
If this fails, then
telnet
will revert to one of two input modes:
either character at a time
or old line by line
depending on what the remote system supports.
When
LINEMODE
is enabled, character processing is done on the
local system, under the control of the remote system.
When input
editing or character echoing is to be disabled, the remote system
will relay that information.
The remote system will also relay
changes to any special characters that happen on the remote
system, so that they can take effect on the local system.
In character at a time mode, most text typed is immediately sent to the remote host for processing.
In old line by line mode, all text is echoed locally, and (normally) only completed lines are sent to the remote host. The local echo character (initially ^E) may be used to turn off and on the local echo (this would mostly be used to enter passwords without the password being echoed).
If the
LINEMODE
option is enabled, or if the
localchars
toggle is
TRUE
(the default for old line by line; see below),
the user's
quit,
intr,
and
flush
characters are trapped locally, and sent as
TELNET
protocol sequences to the remote side.
If
LINEMODE
has ever been enabled, then the user's
susp
and
eof
are also sent as
TELNET
protocol sequences,
and
quit
is sent as a
TELNET
ABORT
instead of
BREAK
.
There are options (see
toggle
autoflush
and
toggle
autosynch
below)
which cause this action to flush subsequent output to the terminal
(until the remote host acknowledges the
TELNET
sequence) and flush previous terminal input
(in the case of
quit
and
intr).
While connected to a remote host, telnet command mode may be entered by typing the telnet escape character (initially ^]). When in command mode, the normal terminal editing conventions are available.
The following telnet commands are available. Only enough of each command to uniquely identify it need be typed (this is also true for arguments to the mode, set, toggle, unset, slc, environ, and display commands).
TELNET
AUTHENTICATE
option.
Valid arguments for the
auth command are as follows:
TELNET
ENCRYPT
option.
Note: Because of export controls, the
TELNET
ENCRYPT
option is not supported outside of the United States and Canada.
Valid arguments for the encrypt command are:
TELNET
ENVIRON
option.
The initial set of variables is taken from the users
environment, with only the
DISPLAY
and
PRINTER
variables being exported by default.
The
USER
variable is also exported if the
-a
or
-l
options are used.
Valid arguments for the environ command are:
TELNET
LOGOUT
option to the remote side.
This command is similar to a
close
command; however, if the remote side does not support the
LOGOUT
option, nothing happens.
If, however, the remote side does support the
LOGOUT
option, this command should cause the remote side to close the
TELNET
connection.
If the remote side also supports the concept of
suspending a user's session for later reattachment,
the logout argument indicates that you
should terminate the session immediately.
TELNET
LINEMODE
option, or, if the remote side does not understand the
LINEMODE
option, then enter character at a time mode.
TELNET
LINEMODE
option, or, if the remote side does not understand the
LINEMODE
option, then attempt to enter old-line-by-line mode.
TRAPSIG
mode of the
LINEMODE
option.
This requires that the
LINEMODE
option be enabled.
EDIT
mode of the
LINEMODE
option.
This requires that the
LINEMODE
option be enabled.
SOFT_TAB
mode of the
LINEMODE
option.
This requires that the
LINEMODE
option be enabled.
LIT_ECHO
mode of the
LINEMODE
option.
This requires that the
LINEMODE
option be enabled.
ENVIRON
option.
If a port is specified
telnet
omits any automatic initialisation of
TELNET
options.
When the port number is preceded by a minus sign,
the initial option negotiation is done.
After establishing a connection, the file
.telnetrc
in the
user's home directory is read.
Lines beginning with a # are
comment lines.
Blank lines are ignored.
Lines that begin
without white space are the start of a machine entry.
The first thing on such a line is a string identifying the machine
that is being connected to.
It may be the hostname or numeric address specified as the argument
host,
the canonical name of that string as determined by
getaddrinfo(3),
or the string
``DEFAULT''
indicating all hosts.
The rest of the line, and successive
lines that begin with white space are assumed to be
telnet
commands and are processed as if they had been typed
in manually to the
telnet
command prompt.
TELNET
ABORT
(Abort
processes)
sequence.
TELNET
AO
(Abort Output) sequence, which should cause the remote system to flush
all output
from
the remote system
to
the user's terminal.
TELNET
AYT
(Are You There)
sequence, to which the remote system may or may not choose to respond.
TELNET
BRK
(Break) sequence, which may have significance to the remote
system.
TELNET
EC
(Erase Character)
sequence, which should cause the remote system to erase the last character
entered.
TELNET
EL
(Erase Line)
sequence, which should cause the remote system to erase the line currently
being entered.
TELNET
EOF
(End Of File)
sequence.
TELNET
EOR
(End of Record)
sequence.
TELNET
GA
(Go Ahead)
sequence, which likely has no significance to the remote system.
TELNET
STATUS
command,
getstatus
will send the subnegotiation to request that the server send
its current option status.
TELNET
IP
(Interrupt Process) sequence, which should cause the remote
system to abort the currently running process.
TELNET
NOP
(No OPeration)
sequence.
TELNET
SUSP
(SUSPend process)
sequence.
TELNET
SYNCH
sequence.
This sequence causes the remote system to discard all previously typed
(but not yet read) input.
This sequence is sent as
TCP
urgent
data (and may not work if the remote system is a
4.2BSD
system -- if
it doesn't work, a lower case r may be echoed on the terminal).
TELNET
DO
cmd
sequence.
Cmd
can be either a decimal number between 0 and 255,
or a symbolic name for a specific
TELNET
command.
Cmd
can also be either
help
or
?
to print out help information, including
a list of known symbolic names.
TRUE
.
The special value
off
turns off the function associated with
the variable, this is equivalent to using the
unset
command.
The
unset
command will disable or set to
FALSE
any of the specified functions.
The values of variables may be interrogated with the
display
command.
The variables which may be set or unset, but not toggled, are
listed here.
In addition, any of the variables for the
toggle
command may be explicitly set or unset using
the
set
and
unset
commands.
LINEMODE
is enabled, and the status character is typed, a
TELNET
AYT
sequence (see
send ayt
above) is sent to the
remote host.
The initial value for the "Are You There"
character is the terminal's status character.
LINEMODE
or old line by line mode, entering this character
as the first character on a line will cause this character to be
sent to the remote system.
The initial value of the eof character is taken to be the terminal's
eof
character.
TELNET
EC
sequence (see
send
ec
above)
is sent to the remote system.
The initial value for the erase character is taken to be
the terminal's
erase
character.
TELNET
AO
sequence (see
send
ao
above)
is sent to the remote host.
The initial value for the flush character is taken to be
the terminal's
flush
character.
LINEMODE
,
these are the
characters that, when typed, cause partial lines to be
forwarded to the remote system.
The initial value for
the forwarding characters are taken from the terminal's
eol and eol2 characters.
TELNET
IP
sequence (see
send
ip
above)
is sent to the remote host.
The initial value for the interrupt character is taken to be
the terminal's
intr
character.
TELNET
EL
sequence (see
send
el
above)
is sent to the remote system.
The initial value for the kill character is taken to be
the terminal's
kill
character.
LINEMODE
or old line by line mode, then this character is taken to
be the terminal's
lnext
character.
The initial value for the lnext character is taken to be
the terminal's
lnext
character.
TELNET
BRK
sequence (see
send
brk
above)
is sent to the remote host.
The initial value for the quit character is taken to be
the terminal's
quit
character.
LINEMODE
or old line by line mode, then this character is taken to
be the terminal's
reprint
character.
The initial value for the reprint character is taken to be
the terminal's
reprint
character.
TELNET
TOGGLE-FLOW-CONTROL
option has been enabled,
then this character is taken to
be the terminal's
start
character.
The initial value for the start character is taken to be
the terminal's
start
character.
TELNET
TOGGLE-FLOW-CONTROL
option has been enabled,
then this character is taken to
be the terminal's
stop
character.
The initial value for the stop character is taken to be
the terminal's
stop
character.
LINEMODE
is enabled, and the
suspend
character is typed, a
TELNET
SUSP
sequence (see
send
susp
above)
is sent to the remote host.
The initial value for the suspend character is taken to be
the terminal's
suspend
character.
TRUE
,
will be written.
If it is set to
``-'',
then tracing information will be written to standard output (the default).
LINEMODE
or old line by line mode, then this character is taken to
be the terminal's
worderase
character.
The initial value for the worderase character is taken to be
the terminal's
worderase
character.
TELNET
LINEMODE
option has
been enabled.
Special characters are characters that get
mapped to
TELNET
commands sequences (like
ip
or
quit)
or line editing characters (like
erase
and
kill).
By default, the local special characters are exported.
TRUE
and
FALSE
)
various flags that control how
telnet
responds to events.
These flags may be set explicitly to
TRUE
or
FALSE
using the
set
and
unset
commands listed above.
More than one argument may be specified.
The state of these flags may be interrogated with the
display
command.
Valid arguments are:
TRUE
,
then when the
ao,
or
quit
characters are recognized (and transformed into
TELNET
sequences; see
set
above for details),
telnet
refuses to display any data on the user's terminal
until the remote system acknowledges (via a
TELNET
TIMING
MARK
option)
that it has processed those
TELNET
sequences.
The initial value for this toggle is
TRUE
if the terminal user had not
done an "stty noflsh", otherwise
FALSE
(see
stty(1)).
TELNET
ENCRYPT
option is negotiated, by
default the actual encryption (decryption) of the data
stream does not start automatically.
The autoencrypt
(autodecrypt) command states that encryption of the
output (input) stream should be enabled as soon as
possible.
Note: Because of export controls, the
TELNET
ENCRYPT
option is not supported outside the United States and Canada.
TELNET
AUTHENTICATION
option
TELNET
attempts to use it to perform automatic authentication.
If the
AUTHENTICATION
option is not supported, the user's login
name are propagated through the
TELNET
ENVIRON
option.
This command is the same as specifying the
-a
option on the
open
command.
TRUE
,
then when either the
intr
or
quit
characters is typed (see
set
above for descriptions of the
intr
and
quit
characters), the resulting
TELNET
sequence sent is followed by the
TELNET
SYNCH
sequence.
This procedure
should
cause the remote system to begin throwing away all previously
typed input until both of the
TELNET
sequences have been read and acted upon.
The initial value of this toggle is
FALSE
.
TELNET
BINARY
option on both input and output.
TELNET
BINARY
option on input.
TELNET
BINARY
option on output.
TRUE
,
then carriage returns will be sent as
<CR><LF>
.
If this is
FALSE
,
then carriage returns will be send as
<CR><NUL>
.
The initial value for this toggle is
FALSE
.
FALSE
.
FALSE
.
TRUE
,
then the
flush,
interrupt,
quit,
erase,
and
kill
characters (see
set
above) are recognized locally, and transformed into (hopefully) appropriate
TELNET
control sequences
(respectively
ao,
ip,
brk,
ec,
and
el;
see
send
above).
The initial value for this toggle is
TRUE
in old line by line mode,
and
FALSE
in character at a time mode.
When the
LINEMODE
option is enabled, the value of
localchars
is ignored, and assumed to always be
TRUE
.
If
LINEMODE
has ever been enabled, then
quit
is sent as
abort,
and
eof and
suspend
are sent as
eof and
susp
(see
send
above).
FALSE
.
FALSE
.
TRUE
,
TELNET
skips the reading of the
.telnetrc
file in the users home
directory when connections are opened.
The initial
value for this toggle is
FALSE
.
FALSE
.
TRUE
,
telnet
prints out a message each time encryption is enabled or
disabled.
The initial value for this toggle is
FALSE
.
Note: Because of export controls, data encryption
is not supported outside of the United States and Canada.
HOME
,
SHELL
,
DISPLAY
,
and
TERM
environment variables.
Other environment variables may be propagated
to the other side via the
TELNET
ENVIRON
option.
~/.telnetrc
In old line by line mode or
LINEMODE
the terminal's
eof
character is only recognized (and sent to the remote system)
when it is the first character on a line.