TERMCAP(5) BSD TERMCAP(5)
NAME
termcap - terminal capability database
SYNOPSIS
/etc/termcap
DESCRIPTION
termcap is a database describing terminals, used, for example, by vi(1)
and curses(3X). 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 and is used by older systems which store the terminal
type in a 16-bit word in a system-wide database. 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 lowercase and contain no blanks; the last name may
well contain uppercase 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
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o indicates capability is obsolete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 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 of bs delay needed (default 0)
db bool Display may be retained below the 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 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 ~s (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 upper right
K3 str Sent by keypad center
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-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 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 non-function 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) 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 (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 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 Non-destructive space (cursor right)
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) 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) 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 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 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:\
: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
(thatis, 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 after the remainder of the string is sent to provide this delay.
The delay can be either a number, for example `20', or a number followed
by an `*', thatis, `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 \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
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 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 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.
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
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 switch-
selectable automatic margins, the termcap description usually assumes
that this feature is on, thatis, 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 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 (for example,
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
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. (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 (for example, 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. 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 mode-
setting 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
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
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
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
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, thatis,
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 terminal-dependent
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
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, 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 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:
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
ex(1), more(1), tset(1), ul(1), vi(1), curses(3X), printf(3S), term(7).
CAVEATS AND CAUTIONS
Note: termcap was replaced by terminfo in DOMAIN/IX BSD4.2. 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 termlib(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.