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LDP/howto/linuxdoc/Text-Terminal-HOWTO.sgml
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@ -2,11 +2,12 @@
<article>
<title> Text-Terminal-HOWTO
<author> David S. Lawyer <url url="mailto:dave@lafn.org">
<date> v1.18, December 2000
<date> v1.19, January 2001
<!--
Change log:
v1.19 Jan. 2001 more on stuck on line 25, more on DEC MMJ cabling,
dual signal ground wires, programs use terminfo w/o ncurses
v1.18 Dec. 2000 mesg command, respawning error cause, chaos when 2
processes open same terminal, rebooting
v1.17 Dec. 2000 Don't run getty from the command line,
@ -90,12 +91,10 @@ maintainer. You may create a derivative work and distribute it
provided that you:
<enum>
<item> Send your derivative work to the LDP (Linux Documentation
Project) or the like for free distribution on the Internet in a
format they will accept. If not the LDP, then let the LDP know
where it is available. Except for a translation, send a copy to the
previous maintainer's url as shown in the latest version.
<item> If it's not a translation: Email a copy of your derivative work
to the LDP (Linux Documentation Project) for free distribution on the
Internet in a format LDP accepts. Also email such a copy to the
author(s) and maintainer (could be the same person).
<item>License the derivative work in the spirit of this license or use
GPL. Include a copyright notice and at least a pointer to the
license used.
@ -147,15 +146,16 @@ accept older ones also). Also, you might want to write up something
on a certain terminal to put in the Appendix D: Notes by Brand Name.
<sect1> New Versions of this HOWTO
<p> New versions of the Text-Terminal-HOWTO will be available to
browse and/or download at LDP mirror sites. For a list of mirror
sites see: <url url="http://linuxdoc.org/mirrors.html">.
Various formats are available. If you only want to quickly check the
date of the latest version look at <url
<p> New versions of the Text-Terminal-HOWTO should be released every
month or two to browse and/or download at LDP mirror sites. For a
list of mirror sites see: <url
url="http://linuxdoc.org/mirrors.html">. Various formats are
available. If you only want to quickly check the date of the latest
version look at <url
url="http://linuxdoc.org/HOWTO/Text-Terminal-HOWTO.html">. The
version your are currently reading is: v1.18, December 2000 . New in this version:
v1.18: mesg command, respawning error cause, chaos when 2 processes
open same terminal, rebooting.
version your are currently reading is: v1.19, January 2001 . New in this version:
v1.19 more on stuck on line 25, more on DEC MMJ cabling, dual signal
ground wires, programs use terminfo w/o ncurses
<sect1> Related HOWTOs, etc. <label id="related_howtos">
<p> Go to the websites shown above to get these.
@ -725,22 +725,23 @@ terminal an escape sequence telling it to split the screen up into
two windows of specified size, not realizing that the terminal was
incapable of doing this.
To overcome these problems a database called "termcap" (meaning "terminal
capabilities") was established. Termcap was superceded by "terminfo".
This database resides in certain files on the computer and has a
section of it (sometimes an entire file) for each model of terminal.
For each model (such as VT100) a list of capabilities is provided
including a list of certain escape sequences available. For example
blink=\E5m means that to make the cursor start blinking the terminal
must be sent: Escape 5 m. See Section <ref id="termcap2"
name="Termcap and Terminfo (detailed)" > for more details.
Application programs may utilize this database by calling certain
C-Library functions. One large set of such programs (over 200) is
named "ncurses" and are listed in the manual page for "ncurses".
To overcome these problems a database called "termcap" (meaning
"terminal capabilities") was established. Termcap was later
superceded by "terminfo". This database resides in certain files on
the computer and has a section of it (sometimes a separate file) for
each model of terminal. For each model (such as VT100) a list of
capabilities is provided including a list of certain escape sequences
available. For example blink=\E5m means that to make the cursor start
blinking the terminal must be sent: Escape 5 m. See Section <ref
id="termcap2" name="Termcap and Terminfo (detailed)" > for more
details. Application programs may utilize this database by calling
certain C-Library functions. One large set of such programs (over
200) is named "ncurses" and are listed in the manual page for
"ncurses".
<sect1> The Interface
<p> The environment variable TERM is the type of terminal Linux thinks
you are using. Some application programs use this to look up the
you are using. Most application programs use this to look up the
capabilities in the terminfo database so TERM needs to be set
correctly. But there is more to a correct interface than the
computer knowing about the capabilities of the terminal.
@ -768,16 +769,28 @@ to emulate a VT100. Wyse is a major terminal manufacturer and most of
their terminals can emulate various DEC terminals such at VT100 and
VT220. Thus if you want to, say, use a VT320 terminal you may either
use a real VT320 in "native" personality or possibly use some other
terminal capable of emulating a VT320. The "native" personalities
usually have more capabilities so, other things being equal, "native"
is usually the best to use.
terminal capable of emulating a VT320.
The "native" personalities usually have more capabilities so, other
things being equal, "native" is usually the best to use. But other
things may not be equal. Since the Linux console emulates a VT102 it
you may want to have a terminal emulate this (or something close to it
such as VT100). This will help insure that some programs that may not
handle terminals properly will still work OK on your terminal. Some
programs will assume that you are using a VT012 if the program can't
find a terminfo for your terminal (or can't find a certain
capability). Thus the failure of a program to work correctly with
your non-vt102 terminal may well be your fault if you don't provide a
good terminfo file for your terminal. Using "native" and then
reporting any bugs will help discover and fix bugs which might not
otherwise get detected.
The most common type of emulation is to use a PC like it was a vt100
terminal (or the like). Programs loaded into the PC's memory permits
this. In Linux (unless you're in X-windows) the PC monitor (called
the console) emulates a terminal of type "Linux" (close to vt100).
Even certain windows within X-windows emulate terminals. See <ref
id="term_emulation" name="Terminal Emulation">.
terminal (or the like). Programs loaded into the PC's memory do the
emulation. In Linux (unless you're in X-windows) the PC monitor
(called the console) emulates a terminal of type "Linux" (close to
vt100). Even certain windows within X-windows emulate terminals. See
<ref id="term_emulation" name="Terminal Emulation">.
<sect1> The Console
@ -1778,7 +1791,7 @@ TxD Transmit Data 3 --> 3 RxD Receive Data
6 DSR Data Set Ready
|
DTR Data Terminal Ready 4 --> 8 DCD Carrier Detect
GND Signal Ground 5 --- 7 GND Signal Ground
SG Signal Ground 5 --- 7 SG Signal Ground
DCD Carrier Detect 1
|
DSR Data Set Ready 6 <-- 20 DTR Data Terminal Ready
@ -1823,7 +1836,7 @@ of the connector, connect RTS and CTS together, and also connect DSR,
DCD and DTR together. This way, when the computer needs a certain
handshaking signal to proceed, it will get it (falsely) from itself.
<sect2> Length Limitations
<sect2> Overcoming Length Limitations <label id="length_">
<p> A cable longer than a 50 feet or so may not work properly at high
speed. Much longer lengths sometimes work OK, especially if the speed
is low and/or the cable is a special low-capacitance type and/or the
@ -1833,6 +1846,28 @@ to cover long distances is to install 2@ line drivers near each serial
port so as to convert unbalanced to balanced (and conversely) and then
use twisted pair cabling. But line drivers are expensive.
Another way to increase the distance is to try to cancel out much of
the magnetic field created by the currents in the transmit and receive
data wires: TxD and RxD. To do this, ground return lines, which have
current which is roughly equal (but in the opposite direction) are
placed next to the the transmit and received wires. Twisted pair has
the best cancellation. Some DEC terminals have two signal ground
wires for this purpose. For example, one pair would be TxD and
SG(TxD) where SG is signal ground. If you use ribbon cable, insure
that the TxD and SG(TxD) wires are right next to each other.
Similarly for the RxD.
If there is only one signal ground wire provided by both the PC and
the terminal, it may be split into two wires in a twisted pair cable
for this purpose. You might think that return currents will be
equally split between the two signal ground wires. This would cancel
out only about half of the magnetic field. But it's better
cancellation than this because return current prefers the path of
least impedance. The return path of a data signal (such as TxD) has
the lowest impedance (due to lower inductance) if it flows back in the
same twisted pair. Although I've haven't seen any experimental test
results for this method, it should allow longer cable lengths.
<sect2> Hardware Flow Control Cables
<p> If you expect to use hardware flow control (handshaking) you will
likely need to make up your own cable (or order one made). Of course,
@ -1858,7 +1893,8 @@ computer cable is best.
<sect2> A Kludge using Twisted-Pair Cable <label
id="twist_pair_kludge">
<p> Although none of the EIA-232 signals are balanced for twisted pair
<p> See also <ref id="length_" name="Overcoming Length Limitations">.
Although none of the EIA-232 signals are balanced for twisted pair
one may attempt to use twisted-pair cable with it. Use one pair for
transmit and another for receive. To do this connect signal ground to
one wire in each of these 2 pair. Only part of the signal ground
@ -2021,20 +2057,33 @@ magnifying glass.
<p> These look like modern telephone connectors but are sometimes not
compatible with telephone connectors. See also <ref
id="rj_conn_install" name="Installing RJ Connectors">. They may be 6,
8, or 10 conductor. RJ11/14 is a 4-6 conductor telephone plug. A
look-alike is a MMJ connector (6-conductor) used on later model VT
(and other) terminals. MMJ has an offset tab and is not compatible
with RJ11/14. However, some connectors have been made that are
compatible with both MMJ or RJ11/14. The MMJ pin-out is: 1-DTR,
2-TXD, 3-TXD GND, 4-RXD GND, 5-RXD, 6-DSR.
8, or 10 conductor.
A null-modem cable with MMJ (or RJ11/14) connectors will connect: 1-6,
2-5, and 3-4. Note that such a cable support DTR/DSR flow control
which is not supported (yet) by Linux. Making up your own 6-conductor
null-modem cable is very simple if you understand that the ordinary
4-conductor telephone cable from the wall to your telephone, used in
hundreds of millions of homes, is also a null-modem cable. Find one
and wire your cable the same way.
<sect3> 6-conductors (including MMJ look-alikes)
<p> RJ11/14 is a 4-6 conductor telephone plug. A look-alike is a MMJ
connector (6-conductor) used on later model VT (and other) terminals.
It's sometimes referred to as a DEC-423. MMJ has an offset tab and is
not compatible with RJ11/14 (unless the tab is cut off). However,
some connectors have been made that are compatible with both MMJ or
RJ11/14. Since MMJ connectors are both hard to find and expensive
some people have forced a RJ11/14 (6 conductor) to fit MMJ by filing
off a tab with a file. The MMJ pin-out is: 1-DTR, 2-TXD, 3-TXD GND,
4-RXD GND, 5-RXD, 6-DSR.
A standard MMJ null-modem cable has a MMJ connector at each end. It
connects to the PC using a MMJ-to-DB adapter. This adapter plugs into
a DB (say 25 pin) connector on the back of the PC and the MMJ
connecter plugs into it. If you don't have such an adapter, you can
make a custom cable with a MMJ (or filed RJ) connector on one end and
a DB connector on the other end.
The standard null-modem cable with two MMJ (or RJ11/14) connectors
will connect: 1-6, 2-5, and 3-4. Note that such a cable supports
DTR/DSR flow control which is not supported (yet) by Linux. Making up
your own standard 6-conductor null-modem cable is very simple if you
understand that the ordinary 4-conductor telephone cable from the wall
to your telephone, used in hundreds of millions of homes, is also a
null-modem cable. Find one and wire your cable the same way.
If you lay such a cable (or your terminal null-modem cable) flat on
the floor (with no twists) you will note that both plugs on the ends
@ -2045,7 +2094,25 @@ everything works OK because each inline coupler is also a null-modem
adapter. Two null-modem devices in series result in a straight-thru
connection.
RJ45 and RJ48 are usually 8-conductor modular telephone plugs.
Here's a custom cable diagram (by Mark Gleaves) for connecting MMJ to
a 9-pin serial port using RTS/CTS flow control:
<tscreen><verb>
DEC MMJ Linux PC DB9
Pin Signal Signal Pin
=== ====== ====== ===
1 DTR -----------------------|---> DSR 6
|---> CTS 8
2 TxD ---------------------------> RxD 2
3 SG (TxD)--------------------|--- SG 5
4 SG (RxD)--------------------|
5 RxD <--------------------------- TxD 3
6 DSR <--------------------------- RTS 7
|--- DTR 4
|--> CD 1
RI 9
</verb></tscreen>
<sect3> 8-conductors and 10-conductors
<p> RJ45 and RJ48 are usually 8-conductor modular telephone plugs.
However some are 10-conductor and are allegedly wider and will not
mate with 8-conductor ones. They are used for both flat telephone
cable and round twisted pair cable. The cable end of the connector
@ -2606,10 +2673,10 @@ boundaries of an actual character may be smaller.
be up to 80 characters in a row (line) on the screen. Many terminals
have a 132 column option but unless you have a large screen, the tiny
characters may be hard to read. {{Set 132 column mode}}. If you set
25 lines, make sure that this is in the terminfo. You should also
put "export LINES=25" into /etc/profile. If you don't it might result
in a scrolling problem (see <ref id="no_scroll_25" name="Terminal
doesn't scroll">
25 lines, make sure that this is in the terminfo. You should also put
"export LINES=25" into /etc/profile and also use: "stty -F /dev/ttySx
rows 25". If you don't it might result in a scrolling problem (see
<ref id="no_scroll_25" name="Terminal doesn't scroll">
<sect2> Cursor
<p> The cursor may be set to appear as a rectangle (= block) {Blk}.
@ -3875,13 +3942,16 @@ part of the screen, scroll the screen, change modes, change appearance
After about 1980, many terminals supported over a hundred different
commands (some of which take numeric parameters).
The normal way in which terminfo gives the its information to an
application program is via the "ncurses" functions that a programmer
may put into a C program. For example if a program wants to move the
cursor to row 3, col 6 it simply calls: move(3,6). The move()
function (part of ncurses) knows how to do this for your terminal
(it can read terminfo). So it sends the appropriate escape sequence to
the terminal to make this particular move for a certain terminal.
One way in which terminfo gives the its information to an application
program is via the "ncurses" functions that a programmer may put into
a C program. For example, if a program wants to move the cursor to row
3, col 6 it simply calls: move(3,6). The move() function (part of
ncurses) knows how to do this for your terminal (it has read
terminfo). So it sends the appropriate escape sequence to the
terminal to make this particular move for a certain terminal.
Some programs get info directly from a terminfo files without using
ncurses. Thus a Linux package that doesn't require ncurses may still
need a terminfo file for your terminal.
The terminfo abbreviations are usually longer than those of termcap
and thus it's easier to guess what they mean. The manual pages for
@ -3902,14 +3972,14 @@ you're now using (including a PC monitor) type "infocmp" and you
should see the source terminfo "file" for it.
To see if your terminal (say vt100) is in the terminfo data base type
"locate vt100". If you don't know what your terminal name is, explore
the listing of files in the compiled database or see <ref
id="term_name" name="What is the terminfo name of my terminal ?">
"locate vt100". If you need to find the terminfo name for your
terminal, explore the listing of files in the compiled database or see
<ref id="term_name" name="What is the terminfo name of my terminal ?">
<sect2> Where is the database located ?
<sect3> Compiled database locations <label id="tc_compiled_locs">
<p> Typing "locate vt100" may show /usr/lib/terminfo/v/vt100,
/usr/share/terminfo/v/vt100, /home/you/.terminfo/v/vt100, and/or
/usr/share/terminfo/v/vt100, /home/.../.terminfo/v/vt100, and/or
/etc/terminfo/v/vt100. All these are possible locations of the
compiled terminfo files. Although the /etc/terminfo directory is not
a standard location for it, having a few terminal types there could be
@ -3920,18 +3990,29 @@ find it if it's in at least one of the locations mentioned above.
Otherwise the environment variable TERMINFO may be set to the path to
this database. Example: TERMINFO=/usr/share/terminfo
For the Debian Distribution of Linux, several commonly used terminals
(including the monitor-console) are in the ncurses-term package.
These are put into /etc/terminfo/. All of the terminals in the
database are in the ncurses-bin package and go into
/usr/share/terminfo/.
If the compiled terminfo is in more than one location, everything is
usually OK until someone gets a new terminfo file(s) (from a newer
distribution, from the net, by editing the old one, etc.). The newer
terminfo needs to be put in all the existing locations (or redundant
locations need to be abolished). If you don't ensure this gets done,
then some application programs could wind up still finding and using the
old (and buggy) terminfo data that sill exists in a "usual" location.
Setting the environment variable TERMINFO to the up-to-date location
(as mentioned above) may help avoid this problem.
usually OK until someone installs new terminfo files (from a newer
distribution, from the net, by editing the old one, etc.). Each new
terminfo file needs replace all the existing older copies of that file
(at various locations) unless you abolish redundant locations. If you
don't ensure this gets done, then some application programs could wind
up still finding and using the old (and possibly buggy) terminfo data
that sill exists in a "possible" location. Setting the environment
variable TERMINFO to the up-to-date location (as mentioned above)
would help avoid this problem.
<sect3> Source-code database locations <label id="tc_source_loc">
<p> The source code you use may reside in /etc/termcap and/or in
<p> While the source-code file may not be installed on your computer
there's another way to get the source-code if you have the compiled
code. Just use the "<tt/infocmp/" command.
The source code file (for all terminals0 may be /etc/termcap and/or
terminfo.src (or another name). See the man pages: terminfo(5) or
termcap(5) for the format required to create (or modify) these source
files. The file terminfo.src may be in various locations on your
@ -3949,7 +4030,8 @@ Linux probably installed the compiled files on your hard disk so you
don't need to compile anything unless you modify /etc/termcap (or
terminfo.src ). "tic" will automatically install the resulting
compiled files into a terminfo directory ready to be used by
application programs.
application programs. Which location it's installed in depends on ...
See "man tic" for the explanation.
<sect2> Look at Your Terminfo <label id="infocmp">
<p> It's a good idea to take a look at the terminfo entry for the
@ -3988,7 +4070,7 @@ graphics character set. These often need more definitions to be added
to the old termcap. This may (or may not) have already been done.
Most terminals had hardware bugs (in their firmware) and sometimes
they were "fixed" by modifying the termcap. Then the manufacturer
these were "fixed" by modifying the termcap. Then the manufacturer
might send out replacement chips which would fix the bug. Not all
owners would bother to get the replacement chips. Thus there may be 2
or more terminfos for your terminal, depending on what firmware chips
@ -4010,8 +4092,8 @@ compiled terminfo file in the correct directory reserved for it.
If you would like to find a better terminfo entry for a certain terminal
than the one supplied, you might try searching the Internet (but what
you find may be worse). If your new terminfo entry is better than the
old one and it seems stable (you've used it for a while with no
you find could be worse). If your new terminfo entry is better than
the old one and it seems stable (you've used it for a while with no
problems) then you should send a copy to the maintainer of terminfo as
noted at the start of the source file for terminfo (or termcap).
@ -4023,14 +4105,15 @@ in, and/or make the terminal emulate another terminal. An
initialization string is not automatically sent to the terminal to
initialize it. One might expect that the getty program should do this
but if it did, one could make a change to the set-up at the terminal
and this change wouldn't be implemented because the init string would
automatically cancel it. You must use a command given on the command
line (or in a shell script) to send the init string such. Such
commands are: "tset", "tput init", or "setterm -initialize".
Sometimes there is no need to send the init string since the terminal
may set itself up correctly when it is powered on (using
options/preferences one has set up and saved in non-volatile memory of
the terminal).
and this change wouldn't be happen because the init string would
automatically cancel it. Application programs don't seem to
initialize either. To do this you must use a command given on the
command line (or in a shell script such as /etc/profile) to send the
init strings. Such commands are: "tset", "tput init", or "setterm
-initialize". Sometimes there is no need to send the init strings
since the terminal may set itself up correctly when it is powered on
(using options/preferences one has set up and saved in the
non-volatile memory of the terminal).
<sect1> TERM Variable <label id="term_var">
<p> The Environment variable TERM should be set to the name of
@ -4683,7 +4766,7 @@ a Key a Few Times">
<item><ref id="cant_login" name="Can't Login"> but login prompt is
OK.
<item><ref id="garbled" name="Garbled Login Prompt">
<item><ref id="blank_" name="No Login Prompt">
<item><ref id="no_login_prompt" name="No Login Prompt">
</itemize>
There are two cases where the terminal goes bad. One is when it's
@ -4891,26 +4974,31 @@ If you are using agetty (often just named getty), the agetty program
will detect and set parity and/or bits/character if you type something.
Try it with a return to see if it fixes it.
<sect1> No Login Prompt <label id="blank_">
<p> This is when nothing at all happens at the terminal, but the
terminal seems to be working OK. One of the first things to do is to
make sure that all cable connections are tight and connected
to the correct connector on both the computer and terminal. Other
causes include defective hardware or cables (must be null-modem),
getty not running, terminal setup at wrong baud-rate, terminal in
local mode, etc.
<sect1> No Login Prompt <label id="no_login_prompt">
<p> If there's no login prompt displayed after hitting the return-key
a few times, first make sure that the terminal is powered on. Is the
computer it's connected to up and running? Use the "top" or "ps"
programs to make sure that a getty (or login) process is running on
the terminal. If getty isn't running, carefully check the format for
calling getty in /etc/inittab. Make sure that it includes the current
runlevel (shown by typing the command "runlevel") and that it is valid
for your flavor of getty. Sometimes killing getty (it will restart
automatically) helps.
At the console (or another working terminal), use "top" or "ps -al" to
see if getty is running on the port. Don't confuse it with getty
programs running on other ports or on the virtual consoles. You will
not get a login prompt unless getty runs. If getty isn't running,
carefully check the format for calling getty in /etc/inittab. Make
sure that it includes the current runlevel (shown by typing the
command "runlevel") and that it is valid for your flavor of getty.
Sometimes killing getty (it will restart automatically) helps.
At this point two different avenues of approach are (you may pursue
more than one at a time).
<sect2> Terminal was working OK
<p> Although hardware failures are possible, the problem is likely due
to something that someone did by mistake. Did someone do something
that might have loosened a cable? Did someone modify /etc/inittab or
make some other change to the software so as to prevent terminal
login? If this doesn't reveal the cause, continue reading.
<sect2> More diagnose
<p> The above should solve most cases (unless you've just installed a
terminal). Other causes include defective hardware or cables (must be
null-modem), terminal setup at wrong baud-rate, terminal in local
mode, etc. At this point two different avenues of approach are (you
may pursue more than one at a time).
<itemize>
<item> <ref id="consoleD" name="Diagnose Problem from the Console">
@ -4944,37 +5032,36 @@ at the computer, then its serial port is dead. Test it with a
software diagnostic test or replace it.
If the serial port is alive, you may want to send a file to it (with
modem controls disabled) and see if anything gets to it. To check for
a transmitted signal with a voltmeter, check for a steady negative
voltage when the line is idle. Then start sending a file (or start
getty). On an analog meter you should see the needle dropping to
almost 0 and fluttering about 0 as it measures short-run averages of
the bit stream. On a digital meter you will not see the fluctuations
as well but you can switch to the AC scale to see the AC voltage
created by the flow of bits. If your meter fails to block out DC on
the AC scale (the default of most analog meters), then you could get a
false high AC reading when looking at the idle DC of -12 V on the AC
scale. Without a meter, you could connect a known good device (such
as another terminal or an external modem) to the serial port and see
if it works OK.
modem controls disabled) and watch the signal on a voltmeter (or other
electronic gadget). To check for a transmitted signal with a voltmeter,
check for a steady negative voltage when the line is idle. Then start
sending a file (or start getty). On an analog meter you should see
the needle dropping to almost 0 and fluttering about 0 as it measures
short-run averages of the bit stream. On a digital meter you will not
see the fluctuations as well but you can switch to the AC scale to see
the AC voltage created by the flow of bits. If your meter fails to
block out DC on the AC scale (the default of most analog meters), then
you could get a false high AC reading when looking at the idle DC of
-12 V on the AC scale. Without a meter, you could connect a known
good device (such as another terminal or an external modem) to the
serial port and see if it works OK.
<sect1> Slow: pauses of several seconds between bursts of characters
<p> You likely have mis-set interrupts> See the Serial-HOWTO section
starting with "Slow:"
<sect1> Terminal doesn't scroll <label id="no_scroll_25">
<p> One reason is that something is wrong with terminfo. Another
<p> One reason may be that something is wrong with terminfo. Another
reason could be that you are outside the scrolling region set for the
terminal. Some programs just assume that your terminal has 24 lines
and set the scrolling region for 24 lines (by an escape sequence sent
to the terminal) without consulting terminfo to see how many lines
there actually are. Then when you use another program it may leave
the cursor on line 25 where it becomes trapped and the terminal will
not scroll. To avoid this problem, create an environment variable
"export LINES=25" and then the programs that assume 24 lines will
hopefully use 25 lines set the scrolling region accordingly. An
alternate way to fix this problem is to use the command "stty rows
25".
terminal. Some stupid programs just assume that your terminal has 24
lines and set the scrolling region for 24 lines (by an escape sequence
sent to the terminal) without consulting terminfo to see how many
lines there actually are. Then when you use another program it may
leave the cursor on line 25 where it becomes trapped and the terminal
will not scroll. To avoid this problem, create an environment
variable "export LINES=25" and also "stty -F /dev/ttySx rows 25".
Then the programs that assume 24 lines will hopefully use 25 lines set
the scrolling region accordingly.
<sect1> Serial Monitoring/Diagnostics <label id="serial_mon">
<p> A few Linux programs will monitor the modem control lines and
@ -5494,6 +5581,8 @@ url="http://www.wyse.com/service/support/kbase/wyseterm.asp"
name="Teemworld Escape Sequences"> is a list of escape sequences (and
control codes) for some terminal emulations (including VT 100, 300,
420, and Wyse).
<item> <url url="http://dickey.his.com/ncurses/ncurses.faq.html"
name="ncurses FAQ">
<item> comp.terminals is the newsgroup for terminals
</itemize>
@ -5508,9 +5597,12 @@ url="http://www.wyse.com/service/support/kbase/wyseterm.asp"
</itemize>
<sect2> Entire Books on Terminals
<p> As far as I know, there is no satisfactory book on text
terminals (unless you are interested in antique terminals of the
1970's).
<p> As far as I know, there is no satisfactory book on text terminals
Although this HOWTO has been published as a book, I don't suggest that
that you buy it if you have access to the online version which I'm
improving on every month or so. The following are mainly of
historical interest:
<itemize>
<item> Handbook of Interactive Computer Terminals by Duane E. Sharp;
Reston Publishing Co. 1977. (mostly obsolete)
@ -6189,4 +6281,3 @@ the set-up (confusing menu design).
END OF Text-Terminal-HOWTO
</article>