4.4BSD/usr/share/man/cat1/tn3270.0

TN3270(1)                    BSD Reference Manual                    TN3270(1)

NNAAMMEE
     ttnn33227700 - full-screen remote login to IBM VM/CMS

SSYYNNOOPPSSIISS
     ttnn33227700 [--dd] [--nn _f_i_l_e_n_a_m_e] [--tt _c_o_m_m_a_n_d_n_a_m_e] [_s_y_s_n_a_m_e [port]]

DDEESSCCRRIIPPTTIIOONN
     TTnn33227700 permits a full-screen, full-duplex connection from a UNIX machine
     to an IBM (or compatible) machine.  TTnn33227700 gives the appearance of being
     logged in to the remote machine from an IBM 3270 terminal.  Of course,
     you must have an account on the machine to which you connect in order to
     log in.  TTnn33227700 looks to the user in many respects like the Yale ASCII
     Terminal Communication System II.  TTnn33227700 is actually a modification of
     the Arpanet TELNET user interface (see telnet(1))  which will, in certain
     circumstances, interpret and generate raw 3270 control streams.

     The flags to ttnn33227700 are as follows:

     --dd          Turn on socket-level tracing (for super-user only) --nn_f_i_l_e_n_a_m_e
                 Specify a file to receive network trace data output (from
                 commands "toggle netdata" and "toggle options", see
                 telnet(1));  the default is for output to be directed to the
                 standard error file.  --tt_c_o_m_m_a_n_d_n_a_m_e Specify a UNIX command to
                 process IBM 4994 style transparent mode data received from
                 the remote IBM machine.

     _s_y_s_n_a_m_e     The name of the remote system.  If the remote name is NOT
                 specified, the user will be prompted for a command (see be-
                 low).

     _p_o_r_t        The port to connect to on the remote system.  Normally,
                 ttnn33227700 attempts to connect to the standard TELNET port (port
                 23) on the remote machine.

     When ttnn33227700 first connects to the remote system, it will negotiate to go
     into 3270 mode.  Part of this negotiation involves telling the remote
     system what model 3270 it is emulating.  In all cases, ttnn33227700 emulates a
     3278 terminal.  To decide which specific model, ttnn33227700 looks at the num-
     ber of lines and columns on the actual terminal (as defined in the TERM
     environment variable; see termcap(5)).  The terminal (or window in which
     ttnn33227700 is running, on multiple window systems) must have at least 80
     columns and 24 lines, or ttnn33227700 will not go into emulation mode.  If the
     terminal does have at least 80 columns and at least 24 lines, the follow-
     ing table describes the emulation:

                       minimum_size      emulated
                       (rows*columns)    terminal
                       --------------    ------------
                       27*132            3278 model 5
                       43*80             3278 model 4
                       32*80             3278 model 3
                       24*80             3278 model 2.

     Emulation of the 3270 terminal is done in the UNIX process.  This emula-
     tion involves mapping 3270-style commands from the host into appropriate
     sequences to control the user's terminal screen.  TTnn33227700 uses curses(3)
     and the _/_u_s_r_/_s_h_a_r_e_/_m_i_s_c_/_t_e_r_m_c_a_p file to do this.  The emulation also in-
     volves simulating the special 3270 keyboard keys (program function keys,
     etc.)  by mapping sequences of keystrokes from the ASCII keyboard into
     appropriate 3270 control strings.  This mapping is terminal dependent and
     is specified in a description file, _/_u_s_r_/_s_h_a_r_e_/_m_i_s_c_/_m_a_p_3_2_7_0, (see
     map3270(5))  or in an environment variable MAP3270 (and, if necessary,
     MAP3270A, MAP3270B, and so on - see mset(1)).  Any special function keys
     on the ASCII keyboard are used whenever possible.  If an entry for the
     user's terminal is not found, ttnn33227700 looks for an entry for the terminal
     type _u_n_k_n_o_w_n. If this is not found, ttnn33227700 uses a default keyboard map-
     ping (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, ttnn33227700 sends an
     ASCII bell (BEL), or a visual bell if defined in the user's termcap en-
     try, to the user's terminal and nothing is sent to the IBM host.

     If ttnn33227700 is invoked without specifying a remote host system name, it en-
     ters local command mode, indicated by the prompt ``tn3270> ''. In this
     mode, ttnn33227700 accepts and executes all the commands of telnet(1),  plus
     one additional command:

     ttrraannssccoomm      Specify UNIX command for IBM 4994 style transparent mode
                   processing.

     TTnn33227700 command mode may also be entered, after connecting to a host, by
     typing a special escape sequence.  If ttnn33227700 has succeeded in negotiating
     3270 mode with the remote host, the escape sequence will be as defined by
     the map3270 (see map3270(5))  entry for the user's terminal type (typi-
     cally control-C); otherwise the escape sequence will initially be set to
     the single character `^]' (control right square bracket).

     While in command mode, any host login session is still alive but tem-
     porarily 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.

FFIILLEESS
     /usr/share/misc/termcap
     /usr/share/misc/map3270

NNOOTTEESS
     The IBM 4994 style transparent mode command is invoked when ttnn33227700 re-
     ceives IBM 4994 style transparent output from the remote host.  Output
     and input pipes are created for communication between the two processes.
     The pipes are closed when a 3270 clear command is received from the re-
     mote hosts, signalling the end of transparent mode output.  Transparent
     mode is necessary for sending ASCII control characters over the 3270 ter-
     minal connection; ASCII graphics terminal support is accomplished this
     way.  Developers of ttrraannssccoomm commands should note that the ttrraannssccoomm stdin
     pipe end will be in CBREAK mode, with ECHO and CRMOD turned off.

EENNVVIIRROONNMMEENNTT
     TTnn33227700 checks the following environment variables: TERM, MAP3270,
     MAP3270[A...]. Information on these can be found in mset(1).  TTnn33227700 also
     checks SHELL, KEYBD and API3270.

SSEEEE AALLSSOO
     mset(1),  telnet(1),  curses(3),  termcap(3),  termcap(5),  map3270(5),

     "Yale ASCII Terminal Communication", _S_y_s_t_e_m _I_I _P_r_o_g_r_a_m
     _D_e_s_c_r_i_p_t_i_o_n_/_O_p_e_r_a_t_o_r_'_s _M_a_n_u_a_l, IBM SB30-1911.

HHIISSTTOORRYY
     The ttnn33227700 command appeared in 4.3BSD.

BBUUGGSS
     Tn3270 is slow and uses system resources prodigiously.

     Not all 3270 functions are supported, nor all Yale enhancements.


     Error conditions (attempting to enter data in a protected field, for ex-
     ample) should cause a message to be sent to the user's terminal instead
     of just ringing a bell.

4.3 Berkeley Distribution        June 6, 1993                                3