NAME
termcap - terminal capability data base

SYNOPSIS
/etc/termcap

DESCRIPTION
Termcap is a data base describing terminals, used, e.g., 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 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o indicates capability is obsolete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 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) is newline, not line feed
nl str (o) Newline character if not
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*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________________________________________________________________________________________________________________________________________________________________________________________________________ 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. maps to an ESC character, ^X maps to a control-X for any m ato linefeed,
appropriate X, and the sequences p
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 72.
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 00 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(1) 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(1). 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 /etc/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(1) 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(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 ‘%’
%doutput value as in printf %d
%2output value as in printf %2d
%3output value as in printf %3d
%.output value as in printf %c
%+xadd x to value, then do %.
%>xyif value > x then add y, no output
%rreverse order of two parameters, no output
%iincrement by one, no output
%nexclusive-or all parameters with 0140 (Datamedia 2500)
%BBCD (16*(value/10)) + (value%10), no output
%DReverse 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 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 , as
because it is not always safe to transmit 0 ^D, and the
system may change or discard them. (Programs using termcap must
set terminal modes so that tabs are not expanded, so 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

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 "equence 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(1). 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(1) 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(1) 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 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. 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. 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.

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 for carriage return then ignore
terminals, which echo 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 ALSO
ex(1), more(1), ul(1)*, vi(1), curses(3), printf(3), termcap(3),
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(1) 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.

__________
* Not currently supported under MachTen