termcap - terminal capability database
termcap
The termcap file is a database describing terminals, used,
for example,
by vi(1) and curses(3). 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 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 last
should be in
lower case and contain no blanks; the last name may well
contain upper
case characters 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 -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 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
The characters in the Notes function 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o Indicates capability is obsolete.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 equivalents,
since they were
considered useless, or are 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
(see BUGS section
below).
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
the screen.
dB num (o) Milliseconds bs delay needed
(default 0).
db bool Display may be retained below
the screen.
DC str (NP*) Delete n characters.
dC num (o) Milliseconds cr delay needed
(default 0).
dc str (P*) Delete character.
dF num (o) Milliseconds 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 nl delay needed
(default 0).
DO str (NP*) Move cursor down: n lines.
do str Down one line.
ds str Disable status line.
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 Can erase overstrikes with a
blank.
EP bool (o) Even parity.
es bool Escape can be used on the status line.
ff str (P*) Hardcopy terminal page eject.
fs str Return from status line.
gn bool Generic line type, for example
dialup,
switch).
hc bool Hardcopy terminal.
HD bool (o) Half-duplex.
hd str Half-line down (forward 1/2
linefeed).
ho str (P) Home cursor.
hs bool Has extra ``status line''.
hu str Half-line up (reverse 1/2
linefeed).
hz bool Cannot print ``~'' (Hazeltine).
i1-i3 str Terminal initialization
strings (terminfo
only)
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 Pathname of program for initialization
(terminfo only).
ip str (P*) Insert pad after character inserted.
is str Terminal initialization string
(termcap only).
it num Tabs initially every n positions.
K1 str Sent by keypad upper left.
K2 str Sent by keypad center.
K3 str Sent by keypad upper right.
K4 str Sent by keypad lower left.
K5 str Sent by keypad lower right.
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-insertmode
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 Has a ``meta'' key (shift,
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 nonfunction
keys.
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) Lower-case 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 (see BUGS
section below).
ll str Last line, first column.
lm num Lines of memory if > li (0
means varies).
ma str (o) Arrow key map (used by vi version 2 only).
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 attribute.
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 Non-destructive space (cursor
right).
NL bool (o) n is newline, not line feed.
nl str (o) Newline character if notn.
ns bool (o) Terminal is a CRT but doesn't
scroll.
nw str (P) Newline (behaves like cr followed by do).
OP bool (o) Odd parity.
os bool Terminal overstrikes.
pb num Lowest baud where delays are
required.
pc str Pad character (default NUL ).
pf str Turn off the printer.
pk str Program function key n to type
string s
(terminfo only).
pl str Program function key n to execute string s
(terminfo only).
pO str (N) Turn on the printer for n
bytes.
po str Turn on the printer.
ps str Print contents of the screen.
pt bool (o) Has hardware tabs (may need to
be set with
is).
px str Program function key n to
transmit string s
(terminfo only).
r1-r3 str Reset terminal completely to
sane modes
(terminfo only).
rc str (P) Restore cursor to position of
last sc.
rf str Name of file containing reset
codes.
RI str (NP) Move cursor right n positions.
rp str (NP*) Repeat character c n times.
rs str Reset terminal completely to
sane modes
(termcap only).
sa str (NP) Define the video attributes.
sc str (P) Save cursor position.
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.
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) Upper-case 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 Upline (cursor up).
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
columns (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 [Toc] [Back]
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*R:am:bl=^G:cd=16*C:ce=16U:cl=2*^L:cm=%+ %+ :
:co#80:.cr=9^M:db:dc=16A:dl=3*B:do=^J:ei=\200:eo:im=P:in:
:ip=16*:is=U758________________________________________________________________________________________________________________________________________________________________________________________________________
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 [Toc] [Back]
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 (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.
Boolean capabilities are defined by their name, fo. They
have no argument.
The presence of a boolean capability name sets its
value to true.
A capability value will be reverted to false, by appending a
@ char after
the name, such as fo@.
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-toend-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 after the remainder of the string is sent to provide
this delay.
The delay can be either a number, such as `20', or a number
followed by
an `*', such as `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 se- tbf map to linefeed, return, tab, backspace, and
quencesn
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 octal
as072. If it is necessary to place a NUL character in a
string capability
it must be encoded as200. (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 a000 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 [Toc] [Back]
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 with vi 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
or bugs in vi.
To easily test a new terminal description you are working on
you can put
it in your home directory in a file called .termcap and programs will
look there before looking in /usr/share/misc/termcap. You
can also set
the environment variable TERMPATH to a list of absolute file
pathnames
(separated by spaces or colons), one of which contains the
description
you are working on, and programs will search them in the order listed,
and nowhere else. See termcap(3). The TERMCAP environment
variable is
usually set to the termcap entry itself to avoid reading
files when
starting up a program.
To get the padding for insert-line right (if the terminal
manufacturer
did not document it), a severe test is to use vi to edit
/etc/passwd at
9600 baud, delete roughly 16 lines from the middle of the
screen, then
hit the `u' key several times quickly. If the display messes up, more
padding is usually needed. A similar test can be used for
insert-character.
Basic Capabilities [Toc] [Back]
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.
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 goes to the bottom
left corner of
the screen and sends the sf (index) string. To scroll text
down, a program
goes 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 switchselectable
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 ``glasstty'' 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 [Toc] [Back]
Cursor addressing and other strings requiring parameters are
described by
a parameterized string capability, with printf(3)-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 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 ``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%r%2c%2Y''.
The Datamedia 2500 needs the current row and column sent encoded in binary
using ``%.''. 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 transmitn, ^D, asdthe system may change or discard them. (Programs using
termcap
must set terminal modes so that tabs are not expanded, st 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==%+ %+ ''.
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, such as the
Tektronix
4025.
Cursor Motions [Toc] [Back]
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 `` sequence on
HewlettPackard
terminals cannot be used for ho.)
Area Clears [Toc] [Back]
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.
(This terminfo
capability is described for completeness. It is unlikely
that any
termcap- using program will support it.)
If the terminal can retain display memory above the screen,
then 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.
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-onthe-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. Underline mode change garbage is specified by
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
mode, 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.
(It is unlikely that a termcap-using program will support this capability,
which is defined for compatibility with terminfo.)
Terminals with the ``magic cookie'' glitches (sg and ug),
rather than
maintaining extra attribute bits for each character cell,
instead deposit
special ``cookies'', or ``garbage characters ,,'' when they
receive modesetting
sequences, which affect the display algorithm.
Some terminals, such as the Hewlett-Packard 2621, automatically leave
standout mode when they move to a new line or when the cursor 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 [Toc] [Back]
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 this 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 this 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
completely
supplanted by the above capabilities.
The ma entry is also used to indicate arrow keys on terminals that have
single-character arrow keys. It is obsolete but still in
use in version
2 of vi which must be run on some minicomputers due to memory limitations.
This field is 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 vi command.
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 [Toc] [Back]
If the terminal needs to be in a special mode when running a
program that
uses these 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 and not screen-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 are normally sent to
the terminal
by the tset program each time the user logs in. They will
be printed in
the following order: is; setting tabs using ct and st; and
finally if.
(Terminfo uses i1-i2 instead of is and runs the program iP
and prints i3
after the other initializations.) A pair of sequences that
does a harder
reset from a totally unknown state can be analogously given
as rs and if.
These strings are output by the reset program, which is used
when the
terminal gets into a wedged state. (Terminfo uses r1-r3 instead of rs.)
Commands are normally placed in rs and rf only if they produce annoying
effects on the screen and are not necessary when logging in.
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. This is normally used by the tset command to determine
whether to set the driver mode for hardware tab expansion,
and whether to
set the tab stops. If the terminal has tab stops that 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 [Toc] [Back]
Certain capabilities control padding in the terminal driver.
These are
primarily needed by hardcopy terminals and are used by the
tset program
to set terminal driver modes appropriately. Delays embedded
in the capabilities
cr, sf, le, ff, and ta will cause the appropriate
delay bits to
be set in the terminal driver. If pb (padding baud rate) is
given, these
values can be ignored at baud rates below the value of pb.
For 4.2BSD
tset, the delays are given as numeric capabilities dC, dN,
dB, dF, and dT
instead.
Miscellaneous [Toc] [Back]
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 (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. (This is a terminfo feature that is unlikely to
be supported
by a program that uses termcap.)
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. 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.
Strings to program function keys can be given as pk, pl, and
px. Each of
these strings takes two parameters: the function key number
to program
(from 0 to 9) and the string to program it with. Function
key numbers
out of this range may program undefined keys in a terminaldependent manner.
The differences among the capabilities are that pk
causes pressing
the given key to be the same as the user typing the given
string; pl
causes the string to be executed by the terminal in local
mode; and px
causes the string to be transmitted to the computer. Unfortunately, due
to lack of a definition for string parameters in termcap,
only terminfo
supports these capabilities.
Glitches and Braindamage [Toc] [Back]
Hazeltine terminals, which do not allow `~' characters to be
displayed,
should indicate hz.
The nc capability, now obsolete, formerly indicated Datamedia terminals,rn for carriage return then ignore a following
which echo
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, has 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 x x.
Similar Terminals [Toc] [Back]
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 cancelled 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:
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.
/usr/share/misc/termcap File containing terminal descriptions.
/usr/share/misc/termcap.db Hash database file containing
terminal descriptions
(see cap_mkdb(1)).
cap_mkdb(1), ex(1), more(1), tset(1), ul(1), vi(1), curses(3), printf(3),
termcap(3), term(7)
The termcap file format appeared in 3BSD.
The Note: termcap functions were replaced by terminfo in
AT&T System V
UNIX Release 2.0. 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. Most programs now use the kernel information primarily; the information
in this file is used only if the kernel does not
have any information.
Vi allows only 256 characters for string capabilities, and
the routines
in termcap(3) do not check for overflow of this buffer. The
total length
of a single entry (excluding only escaped newlines) may not
exceed 1024.
Not all programs support all entries.
OpenBSD 3.6 March 6, 1993
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