termcap(5)
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termcap Miscellany
terminal capability data base
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SYNTAX
/etc/termcap
DESCRIPTION
Termcap is a data base describing terminals used by the
termcap(3X) library. Terminals are described in termcap by
giving a set of capabilities that they have and by describing how
operations are performed. Padding requirements and
initialization sequences are included in termcap.
Entries in termcap consist of a number of `:'-separated fields.
The first entry for each terminal gives the names that are known
for the terminal, separated by `|' characters. The first name is
always two characters long for compatibility with older systems
which store the terminal type in a 16-bit word in a system-wide
data base. The second name given is the most common abbreviation
for the terminal, the last name given should be a long name fully
identifying the terminal, and all others are understood as
synonyms for the terminal name. All names but the first and last
should be in lower case and contain no blanks; the last name may
well contain upper case and blanks for readability.
Terminal names (except for the last, verbose entry) should be
chosen using the following conventions. The particular piece of
hardware making up the terminal should have a root name chosen,
thus hp2621. This name should not contain hyphens. Modes that
the hardware can be in, or user preferences, should be indicated
by appending a hyphen and an indicator of the mode. Therefore, a
vt100 in 132-column mode would be vt100-w. The following
suffixes should be used where possible:
Suffix Meaning Example
-w Wide mode (more than 80 columns) vt100-w
-am With automatic margins (usually default) vt100-am
-nam Without automatic margins vt100-nam
-n Number of lines on the screen aaa-60
-na No arrow keys (leave them in local) concept100-na
-np Number of pages of memory concept100-4p
-rv Reverse video concept100-rv
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CAPABILITIES
The characters in the Notes field in the table have the following
meanings (more than one may apply to a capability):
N indicates numeric parameter(s)
P indicates that padding may be specified
* indicates that padding may be based on the number of lines affected
o indicates capability is obsolete
"Obsolete" capabilities have no terminfo(4) equivalents; either
they were considered useless, or they have been subsumed by other
capabilities. New software should not rely on them at all.
Name Type Notes Description
ae str (P) End alternate character set
AL str (NP*) Add n new blank lines
al str (P*) Add new blank line
am bool Terminal has automatic margins
as str (P) Start alternate character set
bc str (o) Backspace if not ^H
bl str (P) Audible signal (bell)
bs bool (o) Terminal can backspace with ^H
bt str (P) Back tab
bw bool le (backspace) wraps from column 0 to last column
CC str Terminal settable command character in prototype
cd str (P*) Clear to end of display
ce str (P) Clear to end of line
ch str (NP) Set cursor column (horizontal position)
cl str (P*) Clear screen and home cursor
CM str (NP) Memory-relative cursor addressing
cm str (NP) Screen-relative cursor motion
co num Number of columns in a line
cr str (P) Carriage return
cs str (NP) Change scrolling region (VT100)
ct str (P) Clear all tab stops
cv str (NP) Set cursor row (vertical position)
da bool Display may be retained above screen
dB num (o) Milliseconds of bs delay needed (default 0)
db bool Display may be retained below screen
DC str (NP*) Delete n characters
dC num (o) Milliseconds of cr delay needed (default 0)
dc str (P*) Delete character
dF num (o) Milliseconds of ff delay needed (default 0)
DL str (NP*) Delete n lines
dl str (P*) Delete line
dm str Enter delete mode
dN num (o) Milliseconds of nl delay needed (default 0)
DO str (NP*) Move cursor down n lines
do str Move cursor down one line
ds str Disable status line
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dT num (o) Milliseconds of horizontal tab delay needed (default 0)
dV num (o) Milliseconds of vertical tab delay needed (default 0)
ec str (NP) Erase n characters
ed str End delete mode
ei str End insert mode
eo bool Terminal can erase overstrikes with a blank
EP bool (o) Even parity
es bool Escape can be used on status line
ff str (P*) Hardcopy terminal page eject
fs str Return from status line
gn bool Generic line type (e.g. dialup, switch)
hc bool Hardcopy terminal
HD bool (o) Half-duplex
hd str Move a half-line down (forward 1/2 linefeed)
ho str (P) Home cursor
hs bool Terminal has extra "status line"
hu str Move a half-line up (reverse 1/2 linefeed)
hz bool Terminal cannot print tildes (Hazeltine)
IC str (NP*) Insert n blank characters
ic str (P*) Insert character
if str Name of file containing initialization string
im str Enter insert mode
in bool Insert mode distinguishes nulls
ip str (P*) Insert pad after character inserted
is str Terminal initialization string
it num Tabs are initially every n positions
K1 str Sent by keypad upper left key
K2 str Sent by keypad upper right key
K3 str Sent by keypad center key
K4 str Sent by keypad lower left key
K5 str Sent by keypad lower right key
k0-k9 str Sent by function keys 0-9
kA str Sent by insert-line key
ka str Sent by clear-all-tabs key
kb str Sent by backspace key
kC str Sent by clear-screen or erase key
kD str Sent by delete-character key
kd str Sent by down-arrow key
kE str Sent by clear-to-end-of-line key
ke str Out of "keypad transmit" mode
kF str Sent by scroll-forward/down key
kH str Sent by home-down key
kh str Sent by home key
kI str Sent by insert-character or enter-insert-mode key
kL str Sent by delete-line key
kl str Sent by left-arrow key
kM str Sent by insert key while in insert mode
km bool Terminal has a "meta" key (sets parity bit)
kN str Sent by next-page key
kn num (o) Number of function (k0-k9) keys (default 0)
ko str (o) Termcap entries for other non-function keys
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kP str Sent by previous-page key
kR str Sent by scroll-backward/up key
kr str Sent by right-arrow key
kS str Sent by clear-to-end-of-screen key
ks str Put terminal in "keypad transmit" mode
kT str Sent by set-tab key
kt str Sent by clear-tab key
ku str Sent by up-arrow key
l0-l9 str Labels on function keys if not "fn"
LC bool (o) Terminal is lowercase only
LE str (NP) Move cursor left n positions
le str (P) Move cursor left one position
li num Number of lines on screen or page
ll str Move cursor to last line, first column
lm num Lines of memory if > li (0 means varies)
ma str (o) Arrow key map
mb str Turn on blinking attribute
md str Turn on bold (extra bright) attribute
me str Turn off all attributes
mh str Turn on half-bright attribute
mi bool Safe to move while in insert mode
mk str Turn on blank attribute (characters invisible)
ml str (o) Memory lock on above cursor
mm str Turn on "meta mode" (8th bit)
mo str Turn off "meta mode"
mp str Turn on protected attribute
mr str Turn on reverse-video attibute
ms bool Safe to move in standout modes
mu str (o) Memory unlock (turn off memory lock)
nc bool (o) No correctly-working cr (Datamedia 2500, Hazeltine 2000)
nd str Move cursor right one (non-destructive) space
NL bool (o) \n is newline, not line feed
nl str (o) Newline character if not \n
ns bool (o) Terminal is a CRT but doesn't scroll
nw str (P) Newline (behaves like cr followed by do)
OP bool (o) Terminal uses odd parity
os bool Terminal overstrikes
pb num Lowest baud rate where delays are required
pc str Pad character (default NUL)
pf str Turn off printer
pO str (N) Turn on printer for n bytes
po str Turn on printer
ps str Print contents of screen
pt bool (o) Has hardware tabs (may need to be set with is)
rc str (P) Restore cursor to position of last sc
rf str Name of file containing reset string
RI str (NP) Move cursor right n positions
rp str (NP*) Repeat character c n times
rs str Reset terminal completely to sane modes
sa str (NP) Define video attributes
sc str (P) Save cursor position
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se str End standout mode
SF str (NP*) Scroll forward n lines
sf str (P) Scroll text up
sg num Number of garbage chars left by so or se (default 0)
so str Begin standout mode
SR str (NP*) Scroll backward n lines
sr str (P) Scroll text down
st str Set a tab in all rows, current column
ta str (P) Tab to next 8-position hardware tab stop
tc str Entry of similar terminal - must be last entry
te str String to end programs that use termcap
ti str String to begin programs that use termcap
ts str (N) Go to status line, column n
UC bool (o) Terminal is uppercase only
uc str Underscore one character and move past it
ue str End underscore mode
ug num Number of garbage chars left by us or ue (default 0)
ul bool Underline character overstrikes
UP str (NP*) Move cursor up n lines
up str Move cursor up one line
us str Start underscore mode
vb str Visible bell (must not move cursor)
ve str Make cursor appear normal (undo vs/vi)
vi str Make cursor invisible
vs str Make cursor very visible
vt num Virtual terminal number (not supported on all systems)
wi str (N) Set current window
ws num Number of columns in status line
xb bool Beehive (f1=ESC, f2=^C)
xn bool Newline ignored after 80 cols (Concept)
xo bool Terminal uses xoff/xon (DC3/DC1) handshaking
xr bool (o) Return acts like ce cr nl (Delta Data)
xs bool Standout not erased by overwriting (Hewlett-Packard)
xt bool Tabs ruin, magic so char (Teleray 1061)
xx bool (o) Tektronix 4025 insert-line
A Sample Entry
The following entry, which describes the Concept-100, is among
the more complex entries in the termcap file as of this writing.
ca|concept100|c100|concept|c104|concept100-4p|HDS Concept-100:\
:al=3*\E^R:am:bl=^G:cd=16*\E^C:ce=16\E^U:cl=2*^L:cm=\Ea%+ %+ :\
:co#80:.cr=9^M:db:dc=16\E^A:dl=3*\E^B:do=^J:ei=\E\200:eo:im=\E^P:in:\
:ip=16*:is=\EU\Ef\E7\E5\E8\El\ENH\EK\E\200\Eo&\200\Eo\47\E:k1=\E5:\
:k2=\E6:k3=\E7:kb=^h:kd=\E<:ke=\Ex:kh=\E?:kl=\E>:kr=\E=:ks=\EX:\
:ku=\E;:le=^H:li#24:mb=\EC:me=\EN\200:mh=\EE:mi:mk=\EH:mp=\EI:\
:mr=\ED:nd=\E=:pb#9600:rp=0.2*\Er%.%+ :se=\Ed\Ee:sf=^J:so=\EE\ED:\
:.ta=8\t:te=\Ev \200\200\200\200\200\200\Ep\r\n:\
:ti=\EU\Ev 8p\Ep\r:ue=\Eg:ul:up=\E;:us=\EG:\
:vb=\Ek\200\200\200\200\200\200\200\200\200\200\200\200\200\200\EK:\
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:ve=\Ew:vs=\EW:vt#8:xn:\
:bs:cr=^M:dC#9:dT#8:nl=^J:ta=^I:pt:
Entries may continue onto multiple lines by giving a \ as the
last character of a line, and empty fields may be included for
readability (here between the last field on a line and the first
field on the next). Comments may be included on lines beginning
with "#".
Types of Capabilities
Capabilities in termcap are of three types: Boolean capabilities,
which indicate particular features that the terminal has; numeric
capabilities, giving the size of the display or the size of other
attributes; and string capabilities, which give character
sequences that can be used to perform particular terminal
operations. All capabilities have two-letter codes. For
instance, the fact that the Concept has automatic margins (i.e.,
an automatic return and linefeed when the end of a line is
reached) is indicated by the Boolean capability am. Hence the
description of the Concept includes am.
Numeric capabilities are followed by the character `#' then the
value. In the example above co, which indicates the number of
columns the display has, gives the value `80' for the Concept.
Finally, string-valued capabilities, such as ce (clear-to-end-
of-line sequence) are given by the two-letter code, an `=', then
a string ending at the next following `:'. A delay in
milliseconds may appear after the `=' in such a capability, which
causes padding characters to be supplied by tputs(3X) to provide
this delay after the remainder of the string is sent. The delay
can be either a number, e.g., `20', or a number followed by an
`*', e.g., `3*'. An `*' indicates that the padding required is
proportional to the number of lines affected by the operation,
and the amount given is the per-affected-line padding required.
(In the case of insert-character, the factor is still the number
of lines affected; this is always 1 unless the terminal has in
and the software uses it.) When an `*' is specified, it is
sometimes useful to give a delay of the form `3.5' to specify a
delay per line to tenths of milliseconds. (Only one decimal
place is allowed.)
A number of escape sequences are provided in the string-valued
capabilities for easy encoding of control characters there. \E
maps to an ESC character, ^X maps to a control-X for any
appropriate X, and the sequences \n , \r , \t , \b , and \f map
to linefeed, return, tab, backspace, and formfeed, respectively.
Finally, characters may be given as three octal digits after a \,
and the characters ^ and \ may be given as \^ and \\. If it is
necessary to place a : in a capability it must be escaped in
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octal as \072. If it is necessary to place a NUL character in a
string capability it must be encoded as \200. (The routines that
deal with termcap use C strings and strip the high bits of the
output very late, so that a \200 comes out as a \000 would.)
Sometimes individual capabilities must be commented out. To do
this, put a period before the capability name. For example, see
the first cr and ta in the example above.
Preparing Descriptions
We now outline how to prepare descriptions of terminals. The
most effective way to prepare a terminal description is by
imitating the description of a similar terminal in termcap and to
build up a description gradually, using partial descriptions to
check that they are correct. Be aware that a very unusual
terminal may expose deficiencies in the ability of the termcap
file to describe it. To easily test a new terminal description
you can set the environment variable TERMCAP to the absolute
pathname of a file containing the description you are working on
and programs will look there rather than in /etc/termcap.
TERMCAP can also be set to the termcap entry itself to avoid
reading the file when starting up a program.
Basic Capabilities
The number of columns on each line of the display is given by the
co numeric capability. If the display is a CRT, then the number
of lines on the screen is given by the li capability. If the
display wraps around to the beginning of the next line when the
cursor reaches the right margin, then it should have the am
capability. If the terminal can clear its screen, the code to do
this is given by the cl string capability. If the terminal
overstrikes (rather than clearing the position when a character
is overwritten), it should have the os capability. If the
terminal is a printing terminal, with no soft copy unit, give it
both hc and os. (os applies to storage scope terminals, such as
the Tektronix 4010 series, as well as to hard copy and APL
terminals.) If there is a code to move the cursor to the left
edge of the current row, give this as cr. (Normally this will be
carriage-return, ^M.) If there is a code to produce an audible
signal (bell, beep, etc.), give this as bl.
If there is a code (such as backspace) to move the cursor one
position to the left, that capability should be given as le.
Similarly, codes to move to the right, up, and down should be
given as nd, up, and do, respectively. These local cursor
motions should not alter the text they pass over; for example,
you would not normally use "nd= " unless the terminal has the os
capability, because the space would erase the character moved
over.
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A very important point here is that the local cursor motions
encoded in termcap have undefined behavior at the left and top
edges of a CRT display. Programs should never attempt to
backspace around the left edge, unless bw is given, and never
attempt to go up off the top using local cursor motions.
In order to scroll text up, a program moves the cursor to the
bottom left corner of the screen and sends the sf (index) string.
To scroll text down, a program moves the cursor to the top left
corner of the screen and sends the sr (reverse index) string.
The strings sf and sr have undefined behavior when not on their
respective corners of the screen. Parameterized versions of the
scrolling sequences are SF and SR, which have the same semantics
as sf and sr except that they take one parameter and scroll that
many lines. They also have undefined behavior except at the
appropriate corner of the screen.
The am capability tells whether the cursor sticks at the right
edge of the screen when text is output there, but this does not
necessarily apply to nd from the last column. Leftward local
motion is defined from the left edge only when bw is given; then
an le from the left edge will move to the right edge of the
previous row. This is useful for drawing a box around the edge
of the screen, for example. If the terminal has switch-
selectable automatic margins, the termcap description usually
assumes that this feature is on, i.e., am. If the terminal has a
command that moves to the first column of the next line, that
command can be given as nw (newline). It is permissible for this
to clear the remainder of the current line, so if the terminal
has no correctly-working CR and LF it may still be possible to
craft a working nw out of one or both of them.
These capabilities suffice to describe hardcopy and "glass-tty"
terminals. Thus the Teletype model 33 is described as
T3|tty33|33|tty|Teletype model 33:\
:bl=^G:co#72:cr=^M:do=^J:hc:os:
and the Lear Siegler ADM-3 is described as
l3|adm3|3|LSI ADM-3:\
:am:bl=^G:cl=^Z:co#80:cr=^M:do=^J:le=^H:li#24:sf=^J:
Parameterized Strings
Cursor addressing and other strings requiring parameters are
described by a parameterized string capability, with printf(3S)-
like escapes %x in it, while other characters are passed through
unchanged. For example, to address the cursor the cm capability
is given, using two parameters: the row and column to move to.
(Rows and columns are numbered from zero and refer to the
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physical screen visible to the user, not to any unseen memory.
If the terminal has memory-relative cursor addressing, that can
be indicated by an analogous CM capability.)
The % encodings have the following meanings:
%% output `%'
%d output value as in printf %d
%2 output value as in printf %2d
%3 output value as in printf %3d
%. output value as in printf %c
%+x add x to value, then do %.
%>xy if value > x then add y, no output
%r reverse order of two parameters, no output
%i increment by one, no output
%n exclusive-or all parameters with 0140 (Datamedia 2500)
%B BCD (16*(value/10)) + (value%10), no output
%D Reverse coding (value - 2*(value%16)), no output (Delta Data)
Consider the Hewlett-Packard 2645, which, to get to row 3 and
column 12, needs to be sent "\E&a12c03Y" padded for 6
milliseconds. Note that the order of the row and column
coordinates is reversed here and that the row and column are sent
as two-digit integers. Thus its cm capability is
"cm=6\E&%r%2c%2Y".
The Microterm ACT-IV needs the current row and column sent simply
encoded in binary preceded by a ^T, "cm=^T%.%.". Terminals that
use "%." need to be able to backspace the cursor (le) and to move
the cursor up one line on the screen (up). This is necessary
because it is not always safe to transmit \n, ^D, and \r, as the
system may change or discard them. (Programs using termcap must
set terminal modes so that tabs are not expanded, so \t is safe
to send. This turns out to be essential for the Ann Arbor 4080.)
A final example is the Lear Siegler ADM-3a, which offsets row and
column by a blank character, thus "cm=\E=%+ %+ ".
Row or column absolute cursor addressing can be given as single
parameter capabilities ch (horizontal position absolute) and cv
(vertical position absolute). Sometimes these are shorter than
the more general two-parameter sequence (as with the Hewlett-
Packard 2645) and can be used in preference to cm. If there are
parameterized local motions (e.g., move n positions to the right)
these can be given as DO, LE, RI, and UP with a single parameter
indicating how many positions to move. These are primarily
useful if the terminal does not have cm, as with the Tektronix
4025.
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Cursor Motions
If the terminal has a fast way to home the cursor (to the very
upper left corner of the screen), this can be given as ho.
Similarly, a fast way of getting to the lower left-hand corner
can be given as ll; this may involve going up with up from the
home position, but a program should never do this itself (unless
ll does), because it can make no assumption about the effect of
moving up from the home position. Note that the home position is
the same as cursor address (0,0): to the top left corner of the
screen, not of memory. (Therefore, the "\EH" sequence on
Hewlett-Packard terminals cannot be used for ho.)
Area Clears
If the terminal can clear from the current position to the end of
the line, leaving the cursor where it is, this should be given as
ce. If the terminal can clear from the current position to the
end of the display, this should be given as cd. cd must only be
invoked from the first column of a line. (Therefore, it can be
simulated by a request to delete a large number of lines, if a
true cd is not available.)
Insert/Delete Line
If the terminal can open a new blank line before the line
containing the cursor, this should be given as al; this must be
invoked only from the first position of a line. The cursor must
then appear at the left of the newly blank line. If the terminal
can delete the line that the cursor is on, this should be given
as dl; this must only be used from the first position on the line
to be deleted. Versions of al and dl which take a single
parameter and insert or delete that many lines can be given as AL
and DL. If the terminal has a settable scrolling region (like
the VT100), the command to set this can be described with the cs
capability, which takes two parameters: the top and bottom lines
of the scrolling region. The cursor position is, alas, undefined
after using this command. It is possible to get the effect of
insert or delete line using this command - the sc and rc (save
and restore cursor) commands are also useful. Inserting lines at
the top or bottom of the screen can also be done using sr or sf
on many terminals without a true insert/delete line, and is often
faster even on terminals with those features.
If the terminal has the ability to define a window as part of
memory which all commands affect, it should be given as the
parameterized string wi. The four parameters are the starting
and ending lines in memory and the starting and ending columns in
memory, in that order.
If the terminal can retain display memory above the screen, then
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the da capability should be given; if display memory can be
retained below, then db should be given. These indicate that
deleting a line or scrolling may bring non-blank lines up from
below or that scrolling back with sr may bring down non-blank
lines.
Insert/Delete Character
There are two basic kinds of intelligent terminals with respect
to insert/delete character that can be described using termcap.
The most common insert/delete character operations affect only
the characters on the current line and shift characters off the
end of the line rigidly. Other terminals, such as the
Concept-100 and the Perkin Elmer Owl, make a distinction between
typed and untyped blanks on the screen, shifting upon an insert
or delete only to an untyped blank on the screen which is either
eliminated or expanded to two untyped blanks. You can determine
the kind of terminal you have by clearing the screen then typing
text separated by cursor motions. Type "abc def" using local
cursor motions (not spaces) between the "abc" and the "def".
Then position the cursor before the "abc" and put the terminal in
insert mode. If typing characters causes the rest of the line to
shift rigidly and characters to fall off the end, then your
terminal does not distinguish between blanks and untyped
positions. If the "abc" shifts over to the "def" which then move
together around the end of the current line and onto the next as
you insert, then you have the second type of terminal and should
give the capability in, which stands for "insert null". While
these are two logically separate attributes (one line vs. multi-
line insert mode, and special treatment of untyped spaces), we
have seen no terminals whose insert mode cannot be described with
the single attribute.
Termcap can describe both terminals that have an insert mode and
terminals that send a simple sequence to open a blank position on
the current line. Give as im the sequence to get into insert
mode. Give as ei the sequence to leave insert mode. Now give as
ic any sequence that needs to be sent just before each character
to be inserted. Most terminals with a true insert mode will not
give ic; terminals that use a sequence to open a screen position
should give it here. (If your terminal has both, insert mode is
usually preferable to ic. Do not give both unless the terminal
actually requires both to be used in combination.) If post-insert
padding is needed, give this as a number of milliseconds in ip (a
string option). Any other sequence that may need to be sent
after insertion of a single character can also be given in ip.
If your terminal needs to be placed into an `insert mode' and
needs a special code preceding each inserted character, then both
im/ei and ic can be given, and both will be used. The IC
capability, with one parameter n, will repeat the effects of ic n
times.
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It is occasionally necessary to move around while in insert mode
to delete characters on the same line (e.g., if there is a tab
after the insertion position). If your terminal allows motion
while in insert mode, you can give the capability mi to speed up
inserting in this case. Omitting mi will affect only speed.
Some terminals (notably Datamedia's) must not have mi because of
the way their insert mode works.
Finally, you can specify dc to delete a single character, DC with
one parameter n to delete n characters, and delete mode by giving
dm and ed to enter and exit delete mode (which is any mode the
terminal needs to be placed in for dc to work).
Highlighting, Underlining, and Visible Bells
If your terminal has one or more kinds of display attributes,
these can be represented in a number of different ways. You
should choose one display form as standout mode, representing a
good high-contrast, easy-on-the-eyes format for highlighting
error messages and other attention getters. (If you have a
choice, reverse video plus half-bright is good, or reverse video
alone.) The sequences to enter and exit standout mode are given
as so and se, respectively. If the code to change into or out of
standout mode leaves one or even two blank spaces or garbage
characters on the screen, as the TVI 912 and Teleray 1061 do,
then sg should be given to tell how many characters are left.
Codes to begin underlining and end underlining can be given as us
and ue, respectively. If changing the underlining mode leaves
garabage characters on the screen, specify ug, similar to sg. If
the terminal has a code to underline the current character and
move the cursor one position to the right, such as the Microterm
Mime, this can be given as uc.
Other capabilities to enter various highlighting modes include mb
(blinking), md (bold or extra bright), mh (dim or half-bright),
mk (blanking or invisible text), mp (protected), mr (reverse
video), me (turn off all attribute modes), as (enter alternate
character set mode), and ae (exit alternate character set mode).
Turning on any of these modes singly may or may not turn off
other modes.
If there is a sequence to set arbitrary combinations of
attributes, this should be given as sa (set attributes), taking 9
parameters. Each parameter is either 0 or 1, as the
corresponding attributes is on or off. The 9 parameters are, in
order: standout, underline, reverse, blink, dim, bold, blank,
protect, and alternate character set. Not all modes need be
supported by sa, only those for which corresponding attribute
commands exist.
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Some terminals, such as the Hewlett-Packard 2621, automatically
leave standout mode when the cursor is moved to a new line or is
addressed. Programs using standout mode should exit standout
mode on such terminals before moving the cursor or sending a
newline. On terminals where this is not a problem, the ms
capability should be present to say that this overhead is
unnecessary.
If the terminal has a way of flashing the screen to indicate an
error quietly (a bell replacement), this can be given as vb; it
must not move the cursor.
If the cursor needs to be made more visible than normal when it
is not on the bottom line (to change, for example, a non-blinking
underline into an easier-to-find block or blinking underline),
give this sequence as vs. If there is a way to make the cursor
completely invisible, give that as vi. The capability ve, which
undoes the effects of both of these modes, should also be given.
If your terminal correctly displays underlined characters (with
no special codes needed) even though it does not overstrike, then
you should give the capability ul. If overstrikes are erasable
with a blank, this should be indicated by giving eo.
Keypad
If the terminal has a keypad that transmits codes when the keys
are pressed, this information can be given. Note that it is not
possible to handle terminals where the keypad only works in local
mode (this applies, for example, to the unshifted Hewlett-Packard
2621 keys). If the keypad can be set to transmit or not
transmit, give these codes as ks and ke. Otherwise the keypad is
assumed to always transmit. The codes sent by the left-arrow,
right-arrow, up-arrow, down-arrow, and home keys can be given as
kl, kr, ku, kd, and kh, respectively. If there are function keys
such as f0, f1, ..., f9, the codes they send can be given as k0,
k1,..., k9. If these keys have labels other than the default f0
through f9, the labels can be given as l0, l1,..., l9. The codes
transmitted by certain other special keys can be given: kH (home
down), kb (backspace), ka (clear all tabs), kt (clear the tab
stop in the current column), kC (clear screen or erase), kD
(delete character), kL (delete line), kM (exit insert mode), kE
(clear to end of line), kS (clear to end of screen), kI (insert
character or enter insert mode), kA (insert line), kN (next
page), kP (previous page), kF (scroll forward/down), kR (scroll
backward/up), and kT (set a tab stop in the current column). In
addition, if the keypad has a 3 by 3 array of keys including the
four arrow keys, then the other five keys can be given as K1, K2,
K3, K4, and K5. These keys are useful when the effects of a 3 by
3 directional pad are needed. The obsolete ko capability
formerly used to describe "other" function keys has been
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completely supplanted by the above capabilities.
The ma entry is also used to indicate arrow keys on terminals
that have single-character arrow keys. This field is obsolete
and redundant with kl, kr, ku, kd, and kh. It consists of groups
of two characters. In each group, the first character is what an
arrow key sends, and the second character is the corresponding
cursor movement from vi(1). These commands are h for kl, j for
kd, k for ku, l for kr, and H for kh. For example, the Mime
would have "ma=^Hh^Kj^Zk^Xl" indicating arrow keys left (^H),
down (^K), up (^Z), and right (^X). (There is no home key on the
Mime.)
Tabs and Initialization
If the terminal needs to be in a special mode when running a
program that uses termcap capabilities, the codes to enter and
exit this mode can be given as ti and te. This arises, for
example, from terminals like the Concept with more than one page
of memory. If the terminal has only memory-relative cursor
addressing, a screen-sized window must be fixed into the display
for cursor addressing to work properly. This is also used for
the Tektronix 4025, where ti sets the command character to be the
one used by termcap.
Other capabilities include is, an initialization string for the
terminal, and if, the name of a file containing long
initialization strings. These strings are expected to set the
terminal into modes consistent with the rest of the termcap
description. They should be printed in the following order: is;
setting tabs using ct and st; and finally if. A pair of
sequences that does a harder reset from a totally unknown state
can be analogously given as rs and if. Commands are normally
placed in rs and rf only if they produce annoying effects on the
screen and are not usually necessary. For example, the command
to set the VT100 into 80-column mode would normally be part of
is, but it causes an annoying glitch of the screen and is not
normally needed since the terminal is usually already in 80-
column mode.
If the terminal has hardware tabs, the command to advance to the
next tab stop can be given as ta (usually ^I). A "backtab"
command which moves leftward to the previous tab stop can be
given as bt. By convention, if the terminal driver modes
indicate that tab stops are being expanded by the computer rather
than being sent to the terminal, programs should not use ta or bt
even if they are present, since the user may not have the tab
stops properly set. If the terminal has hardware tabs that are
initially set every n positions when the terminal is powered up,
then the numeric parameter it is given, showing the number of
positions between tab stops. If the terminal has tab stops that
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can be saved in nonvolatile memory, the termcap description can
assume that they are properly set.
If there are commands to set and clear tab stops, they can be
given as ct (clear all tab stops) and st (set a tab stop in the
current column of every row). If a more complex sequence is
needed to set the tabs than can be described by this, the
sequence can be placed in is or if.
Delays
Certain capabilities control padding in the terminal driver.
These are primarily needed by hardcopy terminals. The delays
should be embedded as padding information in the cr, sf, le, ff,
and ta capabilities. If pb (padding baud rate) is given, these
values can be ignored at baud rates below the value of pb. The
delays can also be given as (obsolete) numeric capabilities
instead: dC, dN, dB, dF, and dT.
Miscellaneous
If the terminal requires other than a NUL (zero) character as a
pad, this can be given as pc. Only the first character of the pc
string is used.
If the terminal has commands to save and restore the position of
the cursor, give them as sc and rc.
If the terminal has an extra "status line" that is not normally
used by software, this fact can be indicated. If the status line
is viewed as an extra line below the bottom line, then the
capability hs should be given. Special strings to go to a
position in the status line and to return from the status line
can be given as ts and fs. (fs must leave the cursor position in
the same place that it was before ts. If necessary, the sc and
rc strings can be included in ts and fs to get this effect.) The
capability ts takes one parameter, which is the column number of
the status line to which the cursor is to be moved. If escape
sequences and other special commands such as tab work while in
the status line, the flag es can be given. A string that turns
off the status line (or otherwise erases its contents) should be
given as ds. The status line is normally assumed to be the same
width as the rest of the screen, i.e., co. If the status line is
a different width (possibly because the terminal does not allow
an entire line to be loaded), then its width in columns can be
indicated with the numeric parameter ws.
If the terminal can move up or down half a line, this can be
indicated with hu (half-line up) and hd (half-line down). This
is primarily useful for superscripts and subscripts on hardcopy
terminals. If a hardcopy terminal can eject to the next page
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(form feed), give this as ff (usually ^L).
If there is a command to repeat a given character a given number
of times (to save time transmitting a large number of identical
characters), this can be indicated with the parameterized string
rp. The first parameter is the character to be repeated and the
second is the number of times to repeat it.
If the terminal has a settable command character, such as the
Tektronix 4025, this can be indicated with CC. A prototype
command character is chosen which is used in all capabilities.
This character is given in the CC capability to identify it. The
following convention is supported on some UNIX systems: The
environment is to be searched for a CC variable, and if found,
all occurrences of the prototype character are replaced by the
character in the environment variable. This use of the CC
environment variable is a very bad idea, as it conflicts with
make(1).
Terminal descriptions that do not represent a specific kind of
known terminal, such as switch, dialup, patch, and network,
should include the gn (generic) capability so that programs can
complain that they do not know how to talk to the terminal.
(This capability does not apply to virtual terminal descriptions
for which the escape sequences are known.)
If the terminal uses xoff/xon (DC3/DC1) handshaking for flow
control, give xo. Padding information should still be included
so that routines can make better decisions about costs, but
actual pad characters will not be transmitted.
If the terminal has a "meta key" which acts as a shift key,
setting the 8th bit of any character transmitted, then this fact
can be indicated with km. Otherwise, software will assume that
the 8th bit is parity and it will usually be cleared. If strings
exist to turn this "meta mode" on and off, they can be given as
mm and mo.
If the terminal has more lines of memory than will fit on the
screen at once, the number of lines of memory can be indicated
with lm. An explicit value of 0 indicates that the number of
lines is not fixed, but that there is still more memory than fits
on the screen.
If the terminal is one of those supported by the UNIX system
virtual terminal protocol, the terminal number can be given as
vt.
Media copy strings which control an auxiliary printer connected
to the terminal can be given as ps: print the contents of the
screen; pf: turn off the printer; and po: turn on the printer.
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When the printer is on, all text sent to the terminal will be
sent to the printer. It is undefined whether the text is also
displayed on the terminal screen when the printer is on. A
variation pO takes one parameter and leaves the printer on for as
many characters as the value of the parameter, then turns the
printer off. The parameter should not exceed 255. All text,
including pf, is transparently passed to the printer while pO is
in effect.
Glitches and Braindamage
Hazeltine terminals, which do not allow `~' characters to be
displayed, should indicate hz.
The nc capability, now obsolete, formerly indicated Datamedia
terminals, which echo \r \n for carriage return then ignore a
following linefeed.
Terminals that ignore a linefeed immediately after an am wrap,
such as the Concept, should indicate xn.
If ce is required to get rid of standout (instead of merely
writing normal text on top of it), xs should be given.
Teleray terminals, where tabs turn all characters moved over to
blanks, should indicate xt (destructive tabs). This glitch is
also taken to mean that it is not possible to position the cursor
on top of a "magic cookie", and that to erase standout mode it is
necessary to use delete and insert line.
The Beehive Superbee, which is unable to correctly transmit the
ESC or ^C characters, should specify xb, indicating that the "f1"
key is used for ESC and "f2" for ^C. (Only certain Superbees
have this problem, depending on the ROM.)
Other specific terminal problems may be corrected by adding more
capabilities of the form xx.
Similar Terminals
If there are two very similar terminals, one can be defined as
being just like the other with certain exceptions. The string
capability tc can be given with the name of the similar terminal.
This capability must be last, and the combined length of the
entries must not exceed 1024. The capabilities given before tc
override those in the terminal type invoked by tc. A capability
can be canceled by placing xx@ to the left of the tc invocation,
where xx is the capability. For example, the entry
hn|2621-nl:ks@:ke@:tc=2621:
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defines a "2621-nl" that does not have the ks or ke capabilities,
hence does not turn on the function key labels when in visual
mode. This is useful for different modes for a terminal, or for
different user preferences.
FILES
/etc/termcap file containing terminal descriptions
SEE ALSO
termcap(3X), vi(1), curses(3X), printf(3S), term(5), terminfo(4),
captoinfo(1M), infocmp(1M) in the System Manager's Reference for
the DG/UX System.
CAVEATS AND BUGS
Note: termcap is obsoleted by terminfo(4) . The transition will
be relatively painless if capabilities flagged as "obsolete" are
avoided.
Lines and columns are now stored by the kernel as well as in the
termcap entry.
The total length of a single entry (excluding only escaped
newlines) may not exceed 1024.
Not all programs support all entries.
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