TN3270(1) General Commands Manual TN3270(1)
NAME
tn3270 - full-screen remote login to IBM VM/CMS
SYNOPSIS
tn3270 sysname
DESCRIPTION
Tn3270 permits a full-screen, full-duplex connection from a VAX UNIX machine to an IBM machine running VM/CMS giving the appearance of
being logged in directly to the remote machine on an IBM 3270 terminal. Of course you must have an account on the machine to which you
wish to connect in order to log in. Tn3270 looks to the user in many respects like the Yale ASCII Terminal Communication System II.
Tn3270 is actually a modification of the Arpanet TELNET user interface (see telnet(1)) that interprets and generates raw 3270 control
streams.
Emulation of the 3270 terminal is done in the Unix process. This emulation involves mapping 3270-style commands from the host into appro-
priate sequences to control the user's terminal screen. Tn3270 uses curses(3x) and the /etc/termcap file to do this. The emulation also
involves simulating the special 3270 keyboard keys (program function keys, etc.) by mapping sequences of keystrokes from the ASCII key-
board into appropriate 3270 control strings. This mapping is terminal dependent and is specified in a description file,
/usr/share/misc/map3270, (see map3270(5)) or in an environment variable MAP3270 (see mset(1)). Any special function keys on the ASCII key-
board are used whenever possible. If an entry for the user's terminal is not found, tn3270 looks for an entry for the terminal type
unknown. If this is not found, tn3270 uses a default keyboard mapping (see map3270(5)).
The first character of each special keyboard mapping sequence is either an ASCII escape (ESC), a control character, or an ASCII delete
(DEL). If the user types an unrecognized function key sequence, tn3270 sends an ASCII bell (BEL), or a visual bell if defined in the
user's termcap entry, to the user's terminal and nothing is sent to the IBM host.
If tn3270 is invoked without specifying a remote host system name, it enters local command mode, indicated by the prompt ``tn3270>''. In
this mode, tn3270 accepts and executes the following commands:
open connect to a remote host
close close the current connection
quit exit tn3270
z suspend tn3270
status print connection status
? print help information
Other common telnet commands are not available in tn3270. Tn3270 command mode may also be entered, after connecting to a host, by typing a
special escape character (typically control-C).
While in command mode, any host login session is still alive but temporarily suspended. The host login session may be resumed by entering
an empty line (press the RETURN key) in response to the command prompt. A session may be terminated by logging off the foreign host, or by
typing ``quit'' or ``close'' while in local command mode.
FILES
/etc/termcap
/usr/share/misc/map3270
AUTHOR
Greg Minshall
SEE ALSO
mset(1), telnet(1), termcap(3x), termcap(5), map3270(5), Yale ASCII Terminal Communication System II Program Description/Operator's Manual
(IBM SB30-1911)
BUGS
Performance is slow and uses system resources prodigiously.
Not all 3270 functions are supported, nor all Yale enhancements.
4.3 Berkeley Distribution November 27, 1996 TN3270(1)
Check Out this Related Man Page
TELNET(1C) TELNET(1C)
NAME
telnet - user interface to the TELNET protocol
SYNOPSIS
telnet [ host [ port ] ]
DESCRIPTION
Telnet is used to communicate with another host using the TELNET protocol. If telnet is invoked without arguments, it enters command mode,
indicated by its prompt ("telnet>"). In this mode, it accepts and executes the commands listed below. If it is invoked with arguments, it
performs an open command (see below) with those arguments.
Once a connection has been opened, telnet enters an input mode. The input mode entered will be either "character at a time" or "line by
line" depending on what the remote system supports.
In "character at a time" mode, most text typed is immediately sent to the remote host for processing.
In "line by line" mode, all text is echoed locally, and (normally) only completed lines are sent to the remote host. The "local echo char-
acter" (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).
In either mode, if the localchars toggle is TRUE (the default in line mode; see below), the user's quit, intr, and flush characters are
trapped locally, and sent as TELNET protocol sequences to the remote side. 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.
COMMANDS
The following 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, and display commands).
open host [ port ]
Open a connection to the named host. If no port number is specified, telnet will attempt to contact a TELNET server at the default
port. The host specification may be either a host name (see hosts(5)) or an Internet address specified in the "dot notation" (see
inet(3N)).
close
Close a TELNET session and return to command mode.
quit
Close any open TELNET session and exit telnet. An end of file (in command mode) will also close a session and exit.
z
Suspend telnet. This command only works when the user is using the csh(1).
mode type
Type is either line (for "line by line" mode) or character (for "character at a time" mode). The remote host is asked for permis-
sion to go into the requested mode. If the remote host is capable of entering that mode, the requested mode will be entered.
status
Show the current status of telnet. This includes the peer one is connected to, as well as the current mode.
display [ argument... ]
Displays all, or some, of the set and toggle values (see below).
? [ command ]
Get help. With no arguments, telnet prints a help summary. If a command is specified, telnet will print the help information for
just that command.
send arguments
Sends one or more special character sequences to the remote host. The following are the arguments which may be specified (more than
one argument may be specified at a time):
escape
Sends the current telnet escape character (initially "^]").
synch
Sends the 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 4.2 BSD system -- if it doesn't
work, a lower case "r" may be echoed on the terminal).
brk
Sends the TELNET BRK (Break) sequence, which may have significance to the remote system.
ip
Sends the TELNET IP (Interrupt Process) sequence, which should cause the remote system to abort the currently running
process.
ao
Sends the TELNET AO (Abort Output) sequence, which should cause the remote system to flush all output from the remote system
to the user's terminal.
ayt
Sends the TELNET AYT (Are You There) sequence, to which the remote system may or may not choose to respond.
ec
Sends the TELNET EC (Erase Character) sequence, which should cause the remote system to erase the last character entered.
el
Sends the TELNET EL (Erase Line) sequence, which should cause the remote system to erase the line currently being entered.
ga
Sends the TELNET GA (Go Ahead) sequence, which likely has no significance to the remote system.
nop
Sends the TELNET NOP (No OPeration) sequence.
?
Prints out help information for the send command.
set argument value
Set any one of a number of telnet variables to a specific value. The special value "off" turns off the function associated with the
variable. The values of variables may be interrogated with the display command. The variables which may be specified are:
echo
This is the value (initially "^E") which, when in "line by line" mode, toggles between doing local echoing of entered charac-
ters (for normal processing), and suppressing echoing of entered characters (for entering, say, a password).
escape
This is the telnet escape character (initially "^[") which causes entry into telnet command mode (when connected to a remote
system).
interrupt
If telnet is in localchars mode (see toggle localchars below) and the interrupt character is typed, a 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.
quit
If telnet is in localchars mode (see toggle localchars below) and the quit character is typed, a 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.
flushoutput
If telnet is in localchars mode (see toggle localchars below) and the flushoutput character is typed, a 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.
erase
If telnet is in localchars mode (see toggle localchars below), and if telnet is operating in "character at a time" mode, then
when this character is typed, a 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.
kill
If telnet is in localchars mode (see toggle localchars below), and if telnet is operating in "character at a time" mode, then
when this character is typed, a 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.
eof
If telnet is operating in "line by line" mode, entering this character as the first character on a line will cause this char-
acter to be sent to the remote system. The initial value of the eof character is taken to be the terminal's eof character.
toggle arguments...
Toggle (between TRUE and FALSE) various flags that control how telnet responds to events. More than one argument may be specified.
The state of these flags may be interrogated with the display command. Valid arguments are:
localchars
If this is 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 "line by line" mode, and FALSE in "character at a time" mode.
autoflush
If autoflush and localchars are both TRUE, then when the ao, intr, 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 sys-
tem 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)).
autosynch
If autosynch and localchars are both TRUE, then when either the intr or quit characters is typed (see set above for descrip-
tions 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.
crmod
Toggle carriage return mode. When this mode is enabled, most carriage return characters received from the remote host will
be mapped into a carriage return followed by a line feed. This mode does not affect those characters typed by the user, only
those received from the remote host. This mode is not very useful unless the remote host only sends carriage return, but
never line feed. The initial value for this toggle is FALSE.
debug
Toggles socket level debugging (useful only to the superuser). The initial value for this toggle is FALSE.
options
Toggles the display of some internal telnet protocol processing (having to do with TELNET options). The initial value for
this toggle is FALSE.
netdata
Toggles the display of all network data (in hexadecimal format). The initial value for this toggle is FALSE.
?
Displays the legal toggle commands.
BUGS
There is no adequate way for dealing with flow control.
On some remote systems, echo has to be turned off manually when in "line by line" mode.
There is enough settable state to justify a .telnetrc file.
No capability for a .telnetrc file is provided.
In "line by line" mode, the terminal's eof character is only recognized (and sent to the remote system) when it is the first character on a
line.
4.2 Berkeley Distribution May 10, 1986 TELNET(1C)