TERMCAP(5)TERMCAP(5)NAMEtermcap - terminal capability data base
SYNOPSIS
/etc/termcap
DESCRIPTION
Termcap is a data base describing terminals, used, e.g., 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 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
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o indicates capability is obsolete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 (e.g. 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) 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 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) 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 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 (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 after the remainder of the string is sent to
provide this delay. The delay can be either a number, e.g. `20', or a
number followed by an `∗', i.e., `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, 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 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,
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 (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. 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, 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 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.
AUTHOR
William Joy
Mark Horton added underlining and keypad support
FILES
/etc/termcap file containing terminal descriptions
SEE ALSOex(1), more(1), tset(1), ul(1), vi(1), curses(3X), printf(3S), term(7).
CAVEATS AND BUGS
Note: termcap was replaced by terminfo in UNIX System V 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 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.
3rd Berkeley Distribution 1 November 1985 TERMCAP(5)
