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1995-07-25
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463 lines
TTTTEEEERRRRMMMM((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV TTTTEEEERRRRMMMM((((1111))))
NNNNAAAAMMMMEEEE
term - server for multiple communication channels on a
serial link
SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
tttteeeerrrrmmmm [-s speed] [-n on|off] [-c on|off] [-r] [-f arg] [-w
arg] [-t arg] [-o] [-a] [-d lev] [-l file] [-v file] [-1]
DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
_T_e_r_m and its clients support multiple, compressed, and
error-corrected communication channels over a regular serial
link, typically a modem connection. The clients can set up
channels to run an interactive shell on the other system
similarly _r_l_o_g_i_n(1), to execute commands on the other system
similarly _r_s_h(1), to transfer files in either direction, to
redirect X-server connections from one system to the other,
or to redirect any network port connection from one system
to a port on the other. Any of these can occur
simultaneously, and in either direction.
To support these multiple clients, a term daemon on each
system takes control of the device connected to the modem.
So you must compile _t_e_r_m and the clients on both systems.
Source is available by anonymous ftp from
tartarus.uwa.edu.au:/pub/oreillym/term/term???.tar.z and
nic.funet.fi:/pub/OS/Linux/BETA/term???.tar.z
DDDDEEEEFFFFIIIINNNNIIIITTTTIIIIOOOONNNN
Due to the fact that anything _t_e_r_m and its clients can
initiate from one end of the link they will just as happily
initiate from the other, the following frame of reference
will be used throughout this documentation. The remote
system refers to the system at the other end of the modem
link, and the local host refers to the machine you are
typing on, typically the user's home system.
UUUUSSSSAAAAGGGGEEEE
_T_e_r_m is run as a daemon which accepts connections from its
clients and establishes channels for each client's data.
_T_e_r_m must be run on both ends. On the remote system,
execute something like
term -r -n off
Then, on the local system, either exit your comm program and
type
term -v /dev/tty?? [-n off] &
where tty?? is the device name for your modem or serial
port. You may be able to start the local term from within
your comm program, e.g. for xcomm type
Page 1 (printed 7/3/94)
TTTTEEEERRRRMMMM((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV TTTTEEEERRRRMMMM((((1111))))
control-A x "$ term"
Once the term daemons are running at both ends they handle
the transmission of data over the link. These clients
connect to a local _t_e_r_m daemon which establishes a
communication channel with the remote daemon and/or remote
processes. The clients are discussed in detail in
_t_e_r_m__c_l_i_e_n_t_s(1). Briefly, _t_r_s_h runs an interactive shell or
commands on the remote system, _t_u_p_l_o_a_d transfers files from
the local system to the remote, _t_r_e_d_i_r redirects connections
from a port on the local system to a port on the remote
system, _t_x_c_o_n_n redirects X-server connections from the local
system to the remote, and _t_m_o_n monitors client statistics.
OOOOPPPPTTTTIIIIOOOONNNNSSSS
_T_e_r_m accepts a number of command-line options which override
settings established by the termrc file (see below):
----cccc off
Turns off compression. Still does error correction.
Consider this option if you have hardware compression
(ie. v.32.bis) or are transferring compressed files.
The default is to have compression on.
----nnnn on|off
Turns on line noise echoing. Talk requests, writes,
and biffs to the login which is running term will then
appear. This is a useful option to use on the local
end (the end you are sitting at). Without this, you
will never see any talk requests directed to your
remote login. Default is on.
----ffff <number>
Makes term send XON at specified interval. Zero is no
flow control emulation, 10 is a single XON every 10
characters. The default is zero. 100 is a reasonable
value.
----ssss <number>
Specifies a maximum number of bits per second
(baudrate) term will try to send over the serial link.
Term will avoid sending characters at a higher data
rate than this. This overrides the BAUDRATE environment
variable. The default is 2400. This option is needed
as most systems will buffer the data sent to the serial
port. Unfortunately this (unknown) buffering can
interfere with term's packet timeout mechanism. During
setup and tuning it is better to have <number> be too
small rather than too large. For high speed links ( >
9600), making it unlimited is probably advantageous.
This is achieved by setting the number to zero. Term
will then rely solely on the packet windows to do flow
Page 2 (printed 7/3/94)
TTTTEEEERRRRMMMM((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV TTTTEEEERRRRMMMM((((1111))))
control.
----wwww <number>
Sets the transmission window size, that is, the number
of unacknowledged packets that term may send. Lower
numbers may lead to better interactive response times.
Higher numbers may lead to better throughput,
particularly if the serial link latencies are large and
the timeout length is set large. Higher numbers can
also improve efficiency on noisy lines. Default is 3.
This will be too low for higher speed links. A
reasonable value is 10 with a timeout (see below) of
150 for 14.4Kbps link.
----tttt <number>
Timeout length in 20ths of a second. This specifies
how long term will wait for an acknowledgement before
retransmitting a packet. Default is 50, maximum 200.
Increasing both the window size and timeout can lead to
improved throughput, but at the expense of greater
latencies for interactive work and during noise
recovery.
----rrrr Use this on the remote term so that client numbers
won't clash.
----aaaa Turns on seven bit line mode. Use only if you have a
seven bit line, as determined by _l_i_n_e_c_h_e_c_k.
----llll <filename>
Output all log/noise/debugging to the file <filename>
----vvvv <filename>
Set the modem device to be <filename>. Appropriate
usage is something like "-v/dev/ttys1"
----1111 Use stdout instead of stdin as the modem port. This is
ignored if a -v is also present.
----dddd <<<<nnnnuuuummmmbbbbeeeerrrr>>>>
This sets the debuging level. This is useful for
monitoring packet timeout conditions and other things.
Level 64 is suggested, 478 is verbose. Read debug.h
and the other source files to find out what the levels
do. If you are not familiar with packet protocols and
pouring through source code, then this option is
unlikely to help you.
----oooo Turns on packet send forcing. Re-transmits oldest
packet if nothing to send. Default off. Of dubious
utility. Not properly debugged. Very bad idea if speed
is unlimited.
Page 3 (printed 7/3/94)
TTTTEEEERRRRMMMM((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV TTTTEEEERRRRMMMM((((1111))))
IIIINNNNIIIITTTTIIIIAAAALLLLIIIIZZZZAAAATTTTIIIIOOOONNNN FFFFIIIILLLLEEEE
The file _t_e_r_m_r_c in the ._t_e_r_m directory in your home
directory may be used to specify default settings for a
user. These settings are overruled by values set in the
command line, but several options can only be set in this
file. Blank lines and lines beginning with '#' are
comments, other lines must begin with one of the options,
and, if an argument is required, it must be separated from
the option by exactly one space. Legal options are:
_e_s_c_a_p_e <number>
This is one of the most important options for term.
Usage is either 'escape <some decimal number>' or
'escape <start of range>-<end of range>'. This tells
term to never transmit the character or characters in
the range. This is essential for serial lines that
aren't fully transparent. For example, lines that use
software flow control will want to do 'escape 17' and
'escape 19'. If you only have a seven-bit link, DO NOT
use 'escape 128-255', see the termrc 'sevenbit' option
below. See also the linecheck program, and
_t_e_r_m__s_e_t_u_p(1).
_i_g_n_o_r_e <number>
This tells term to silently strip this character if it
is received over the serial link. Its use should
correspond to 'escape' options used by the term on the
other system. E.g. if you use 'escape 126' on one end,
you should use 'ignore 126' on the other.
_c_o_m_p_r_e_s_s [on|off].
Turns the default compression mode on or off. The
default is 'compress on'. With this on, all data will
be compressed by term before sending over the serial
line, and then un-compressed at the other end. If you
are sending already compressed data, it is recommended
that you turn compression off. Similarly, if your
modem already does compression you may consider leaving
it off. You can turn compression on and off on a
client-by-client basis with the '-c' option for
clients. See _t_e_r_m__c_l_i_e_n_t_s(1).
_b_a_u_d_r_a_t_e <number>.
This is used to limit the rate at which term sends
data. Set this to the minimum of your modem speed, and
the computer-to-modem baud rate. Values that are too
high shouldn't hurt too much, as long as _t_i_m_e_o_u_t is not
set too low. Default is 2400.
_t_i_m_e_o_u_t <number>.
Set the number of 1/20th of a second to wait before
re-sending packets that haven't been acknowledged. Low
Page 4 (printed 7/3/94)
TTTTEEEERRRRMMMM((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV TTTTEEEERRRRMMMM((((1111))))
values will provide faster recovery from line noise,
but higher values are required if the latencies in your
link are large. Values between 50 and 120 are typical.
The default value is 70.
_w_i_n_d_o_w <number>
The size of the packet window. Default value is 3.
Increase this if your latencies (and timeout) are
large.
_n_o_i_s_e on
If this is set, then term will send anything it doesn't
understand to the standard error or the -l file. This
is where talk requests, mail biffs, writes, and
corrupted packets will end up. This is recommended for
the local end.
_r_e_m_o_t_e
Sets this to the remote side. It should always be
specified on one, and only one end of the link. This
prevents client number clashes.
_s_e_v_e_n_b_i_t
Use this if your line is a sevenbit line. Use this
instead of 'escape 128-255'.
_b_r_e_a_k_o_u_t <number>
The value of breakout character. Default is 48 ('0').
If either 'term' daemon receives five breakout
characters in a row from the link, outside a packet, it
will exit.
_c_h_d_i_r <path>
Sets the home directory for the term daemon. This will
be the directory for processes started started by this
daemon for remote _t_r_s_h clients. And it will be used by
a remote _t_u_p_l_o_a_d when relative paths are used.
_d_e_n_y_r_s_h on
If this is set, any _t_r_s_h request from the other end
will be rejected. This is to provide better security,
especially when run as root. You can set this on both
ends separately, allowing access on one end and denying
on the other.
_c_h_r_o_o_t <directory>
Runs term in a _c_h_r_o_o_t environment (see _c_h_r_o_o_t(2),
_f_t_p_d(8)). If term is run as root, a _t_u_p_l_o_a_d from the
other side could clobber every file on the system. To
avoid this, a _c_h_r_o_o_t environment can be set up to give
access only to specific directories. It accordingly
restricts the commands that can be used by _t_r_s_h. The
Page 5 (printed 7/3/94)
TTTTEEEERRRRMMMM((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV TTTTEEEERRRRMMMM((((1111))))
_c_h_r_o_o_t takes place after every file access in the
initialisation process, in particular after the server
socket is opened.
EEEENNNNVVVVIIIIRRRROOOONNNNMMMMEEEENNNNTTTT VVVVAAAARRRRIIIIAAAABBBBLLLLEEEESSSS
BBBBAAAAUUUUDDDDRRRRAAAATTTTEEEE
Used to set the speed. Overridden by termrc or command
line setting.
SSSSHHHHEEEELLLLLLLL
Default shell for _t_r_s_h.
DDDDIIIISSSSPPPPLLLLAAAAYYYY
Used by _t_x_c_o_n_n to determine which X-server port to use.
TTTTEEEERRRRMMMMDDDDIIIIRRRR
Where to make the .term directory (which contains the
socket for _t_e_r_m itself). Default is HOME.
DDDDIIIIAAAAGGGGNNNNOOOOSSSSTTTTIIIICCCCSSSS
The ----dddd option provides debugging output. See _t_e_r_m__s_e_t_u_p(1),
_l_i_n_e_c_h_e_c_k(1), or _l_i_n_e_r_e_m(1) for further diagnostic
information.
SSSSEEEEEEEE AAAALLLLSSSSOOOO
_t_e_r_m__c_l_i_e_n_t_s(1)
The man page for the term clients.
_t_e_r_m__s_e_t_u_p(1)
The man page for the linecheck program and the test
program for debugging your serial link and exercising
term and clients.
_t_e_r_m/_R_E_A_D_M_E
The original documents for _t_e_r_m from which these man
pages were written.
_t_e_r_m/_O_P_T_I_O_N_S
Another list of options term accepts.
_t_e_r_m/_T_E_R_M_R_C
Another description of the syntax and options the user
may set in ~/.term/termrc.
_t_e_r_m/_C_H_A_N_G_E_S
A list of changes to the program since these manuals
were edited. (version 1.0.6a)
BBBBUUUUGGGGSSSS
If a remote client stops consuming its input but leaves the
channel open, the local term daemon will continue to resend
unacked packets. _T_e_r_m by default requires a line which
Page 6 (printed 7/3/94)
TTTTEEEERRRRMMMM((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV TTTTEEEERRRRMMMM((((1111))))
passes through all ascii values from 0 to 255. Xyplex-type
terminal servers may require the use of set session passall
to work correctly.
AAAAUUUUTTTTHHHHOOOORRRR
Michael O'Reilly, oreillym@tartarus.uwa.edu.au.
Page 7 (printed 7/3/94)