term
Hopefully, this should just involve a make
, if this
doesn't work, you may have to do some hacking. Make sure that you've
got the same version on all machines you want to run term
on - different versions of term
are incompatible. Seek out
and destroy any old binaries on your system - or know how to avoid
them.
term
Do a make test
to build term
's test daemon. Test
works by running two copies of term
on your system, a
``local'' and a ``remote'' copy. Both of these will read your
termrc,
so you can adjust their behaviour. Run test
as ./test
so as to avoid your system's test.
You
should now be able to do a trsh
and a tupload
(try
tupload ./term /usr/tmp
- you should get a copy of the
term
binary in /usr/tmp
). The local
term
's output should show up in local.log,
the
remote's in remote.log.
You can start term
up with
a -d255
flag to enable debugging output to be written to
these files, or enable debugging in your termrc.
Presumably, you can establish a modem connection between your local
and remote hosts. Typically, your dialing into some kind of terminal
server and connecting to your remote host from there. You are also
using some kind of terminal software, such as kermit
or
seyon
to talk to your modem (the examples in this document
will use kermit,
since that is what its author uses). If
you're having trouble with your modem, or your terminal software, take
a look at the Serial HOWTO, that should help you out.
Having established your link, you want to make it as transparent as possible. Check the commands on the terminal server (help or ? will usually get you started). Go for the 8 bit options whenever possible. This may mean changing the way you log in to a system, e.g. if the server uses rlogin, you may have to use it and give it the -8 flag to make it transparent. Especially watch out for xon/xoff flow control, you don't want that, try to enable rts/cts (hardware) flow control. You may need to check your modem docs to learn how to configure it to do 8-bit rts/cts communications.
linecheck
is program that is supplied that with term
that checks the transparency of a link, providing configuration
information that term
needs to run correctly.
linecheck
will send each of the 255 possible eight bit
characters over the link and verify that each was transmitted
successfully. term
needs to be configured to deal with
characters that cannot be transmitted over the link, and
linecheck
determines what characters these are. You use
linecheck
after you've established as transparent a modem
link as possible. To run linecheck,
do the following
linecheck linecheck.log.
ˆZ
under kermit)
(otherwise it will steal characters from linecheck). linecheck linecheck.log >
/dev/modem < /dev/modem.
When linecheck
is done, you'll find a set of numbers at the
bottom of the linecheck.log
files. These should be escaped
in the termrc at the other end of the link. For example, on my system,
my local linecheck.log
said nothing and my remote linecheck.log
said to escape 29 and 157. Therefore, my local
termrc
escapes these characters and my remote termrc
escapes nothing. If I escape
a character on one end,
I have to also ignore
it on the other, so, in this example,
I'll have to ignore 29 and 157 on my remote system.
If linecheck hangs, try using
linecheck linecheck.log 17 19 > /dev/modem < /dev/modem
this will escape your xon/xoff (flow control) characters, which will
hang your line if you've got software flow control. If this solves the
hanging problems, you'll want to escape
/ignore
17/19 in both termrc
's. If your terminal server has other
demonic characters that will shut it down, try running linecheck with
those characters escaped, as above. You can spot these characters if
linecheck
hangs. If this is the case, kill it, then look in
the logfiles. The last characters transmitted are likely to be the
culprits. Try it again with these characters escaped.
In summary, my local termrc has the lines
escape 29 escape 157and my remote termrc has the lines
ignore 29 ignore 157since my remote
linecheck.log
said to escape 29
and 157.
term
Log into the remote system, making the link as transparent as possible
(if you haven't already). Fire up term
on the remote end.
I use the following:
exec term -l $HOME/tlog -s 38400 -c off -w 10 -t 150.
Let's run down each option one by one (note that I could just as
easily have put these options in my termrc. I did it this way because
it saves editing a file while getting term
set up).
exec
means to destroy your current shell, running the given
program in its place. I exec
things because I don't intend
to use my login shell again, so it's just wasting memory. If you're
debugging the link and can reliably kill the remote term,
you might not want to do an exec.
-l $HOME/tlog.
This logs errors to the file tlog
in my home directory. Very useful for debugging. No reason not
to do this.
-s 38400
: I've got a 14400 baud modem, with compression.
For optimal compression ratios, I want to be able to push bits down
the pipe as fast as possible. For a slower modem, you should use
something lower. Note that if you have a slower machine with 16450
uart on your serial port, high baudrates can cause data loss by
overloading the chip on your serial port. term
will recover
from this, but if you see a lot of error messages in your log file,
(or get overrun warnings from linux kernel versions 0.99pl15 and up)
you again might want to lower this number.
-c off
: This turns data compression off. I've got a
compressing modem, and I don't want to compress things twice.
-w 10 -t 150
: Again, these are options to optimize my fast
modem link. I have set my window to 10 and my timeout to 150. This is
per the recommendation in the term_setup
man page.
Suspend your comm program (ˆZ
under kermit). You don't want
it running while term
is running, because it will fight
with term
over the serial port. If you can convince your
modem to not hang up when you exit your comm program (when it toggles
DTR), you could just exit the program at this point.
Now run term
locally. I use:
term -r -c off -l $HOME/tlog -s 38400 -w 10 -t 150
\ < /dev/modem > /dev/modem &
The only option here that is different from the other end is the -r
option. You need this on one end, otherwise term
clients will spontaneously die on you. I need to tell term
where the modem is, so I point both standard input and output at /dev/modem
(that's what the <
and >
do). I
also run it in the background, so I can use this screen for something
else if I want to.
term
should work now :-). Try a trsh,
and see
what happens. If you hang, or your link seems slow, take a look at
your tlog
on each end. Are you getting timeouts or error
messages? If so, then you've configured something incorrectly. Try
again (after you've finished reading this :-). Note that the
connection won't seem blazingly fast, especially if you're using
compression - it will be a little jumpy. The real speed comes in
during file transfer and the like.
Are you running the right binary? term
has been updated
quite a lot, and many systems have different versions of the programs
floating around. Make sure you're using the right version. Note that
this applies to linecheck too. You can use bash's type -a
or the whereis
command to find which program is being run.
term
versions after 1.11 should print out their version
number when they start up. (Although version 1.14 claims to be 1.12.
Sigh.)
Do you have the right termrc
? Is it called
$HOME/.term/termrc
?
Some systems have pre-installed termrc's, make
sure they're gone before you set things up. If you're running things
as root, lookout for /.term.
term
creates files
(sockets actually) while it's running, so it has its own directory,
$HOME/.term,
where the file termrc
goes
(note, there is no leading dot in termrc
!).
Once you've got term
running, you might want to try to get
things optimized. A good way to measure the speed of your link is to
run tmon
in one window while up/downloading a file in
another. Try both (big) text files and compressed files, the plain
text should go a factor of two-ish faster than the compressed files.
The parameters you want to fiddle with are compression (-c
),
windows (-w
) and timeout (-t
).
Compression
you want this on if you don't have a
compressing modem. If you do have such a modem, turn compression off,
otherwise you'll be compressing things twice, which typically increasesthe amount of data transmitted. Compressing modems are
ones that use the MNP-5 or V42.bis protocols. Check your modem
documentation and the message when your modem connects.
Windows
this is the number of chunks of data, or packets,
that term
will let go over the line before it gets an
acknowledgment (or ack) from the remote term.
For fast
modems, increasing this can be a win, for slower links this can
overwhelm the remote end.
Timeout
the time term
will wait for an ack. If
you've increased windows, and you're getting timeouts in your logfile,
try increasing this.
For 14400/V42.bis, I use -c off -w 10 -t 150.
I typically
get around 1700 cps on compressed files and 3500 cps on ascii files
using tupload.