TERMCAP(5) GENIX Programmer's Manual TERMCAP(5)
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 which 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 which are known for
the terminal, separated by `|' characters. The first name is always
2 characters long and is used by older version 6 systems which store
the terminal type in a 16 bit word in a systemwide data base. The
second name given is the most common abbreviation for the terminal,
and the last name given should be a long name fully identifying the
terminal. The second name should contain no blanks; the last name
may well contain blanks for readability.
CAPABILITIES
(P) indicates padding may be specified
(P*) indicates that padding may be based on no. lines affected
Name Type Pad? Description
ae str (P) End alternate character set
al str (P*) Add new blank line
am bool Terminal has automatic margins
as str (P) Start alternate character set
bc str Backspace if not ^H
bs bool Terminal can backspace with ^H
bt str (P) Back tab
bw bool Backspace wraps from column 0 to last column
CC str Command character in prototype if terminal settable
cd str (P*) Clear to end of display
ce str (P) Clear to end of line
ch str (P) Like cm but horizontal motion only, line stays same
cl str (P*) Clear screen
cm str (P) Cursor motion
co num Number of columns in a line
cr str (P*) Carriage return, (default ^M)
cs str (P) Change scrolling region (vt100), like cm
cv str (P) Like ch but vertical only.
da bool Display may be retained above
dB num Number of millisec of bs delay needed
db bool Display may be retained below
dC num Number of millisec of cr delay needed
dc str (P*) Delete character
dF num Number of millisec of ff delay needed
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dl str (P*) Delete line
dm str Delete mode (enter)
dN num Number of millisec of nl delay needed
do str Down one line
dT num Number of millisec of tab delay needed
ed str End delete mode
ei str End insert mode; give ":ei=:" if ic
eo str Can erase overstrikes with a blank
ff str (P*) Hardcopy terminal page eject (default ^L)
hc bool Hardcopy terminal
hd str Half-line down (forward 1/2 linefeed)
ho str Home cursor (if no cm)
hu str Half-line up (reverse 1/2 linefeed)
hz str Hazeltine; can't print ~'s
ic str (P) Insert character
if str Name of file containing is
im bool Insert mode (enter); give ":im=:" if ic
in bool Insert mode distinguishes nulls on display
ip str (P*) Insert pad after character inserted
is str Terminal initialization string
k0-k9 str Sent by "other" function keys 0-9
kb str Sent by backspace key
kd str Sent by terminal down arrow key
ke str Out of "keypad transmit" mode
kh str Sent by home key
kl str Sent by terminal left arrow key
kn num Number of "other" keys
ko str Termcap entries for other non-function keys
kr str Sent by terminal right arrow key
ks str Put terminal in "keypad transmit" mode
ku str Sent by terminal up arrow key
l0-l9 str Labels on "other" function keys
li num Number of lines on screen or page
ll str Last line, first column (if no cm)
ma str Arrow key map, used by vi version 2 only
mi bool Safe to move while in insert mode
ml str Memory lock on above cursor.
ms bool Safe to move while in standout and underline mode
mu str Memory unlock (turn off memory lock).
nc bool No correctly working carriage return (DM2500,H2000)
nd str Non-destructive space (cursor right)
nl str (P*) Newline character (default \n)
ns bool Terminal is a CRT but doesn't scroll.
os bool Terminal overstrikes
pc str Pad character (rather than null)
pt bool Has hardware tabs (may need to be set with is)
se str End stand out mode
sf str (P) Scroll forwards
sg num Number of blank chars left by so or se
so str Begin stand out mode
sr str (P) Scroll reverse (backwards)
ta str (P) Tab (other than ^I or with padding)
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tc str Entry of similar terminal - must be last
te str String to end programs that use cm
ti str String to begin programs that use cm
uc str Underscore one char and move past it
ue str End underscore mode
ug num Number of blank chars left by us or ue
ul bool Terminal underlines even though it doesn't overstrike
up str Upline (cursor up)
us str Start underscore mode
vb str Visible bell (may not move cursor)
ve str Sequence to end open/visual mode
vs str Sequence to start open/visual mode
xb bool Beehive (f1=escape, f2=ctrl C)
xn bool A newline is ignored after a wrap (Concept)
xr bool Return acts like ce \r \n (Delta Data)
xs bool Standout not erased by writing over it (HP 264?)
xt bool Tabs are destructive, magic so char (Teleray 1061)
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. (This
particular concept entry is outdated, and is used as an example
only.)
c1|c100|concept100:is=\EU\Ef\E7\E5\E8\El\ENH\EK\E\200\Eo&\200:\
:al=3*\E^R:am:bs:cd=16*\E^C:ce=16\E^S:cl=2*^L:cm=\Ea%+ %+ :co#80:\
:dc=16\E^A:dl=3*\E^B:ei=\E\200:eo:im=\E^P:in:ip=16*:li#24:mi:nd=\E=:\
:se=\Ed\Ee:so=\ED\EE:ta=8\t:ul:up=\E;:vb=\Ek\EK:xn:
Entries may continue onto multiple lines by giving a \ as the last
character of a line, and that empty fields may be included for rea-
dability (here between the last field on a line and the first field
on the next). Capabilities in termcap are of three types: Boolean
capabilities which indicate that the terminal has some particular
feature, numeric capabilities giving the size of the terminal or the
size of particular delays, and string capabilities, which give a
sequence which can be used to perform particular terminal opera-
tions.
Types of Capabilities
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
capability am. Hence the description of the Concept includes am.
Numeric capabilities are followed by the character `#' and then the
value. Thus co which indicates the number of columns the terminal
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 character code, an `=', and then
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a string ending at the next following `:'. A delay in milliseconds
may appear after the `=' in such a capability, and padding charac-
ters are supplied by the editor after the remainder of the string is
sent to provide this delay. The delay can be either a integer, e.g.
`20', or an integer followed by an `*', i.e. `3*'. A `*' indicates
that the padding required is proportional to the number of lines
affected by the operation, and the amount given is the per-
affected-unit padding required. When a `*' is specified, it is
sometimes useful to give a delay of the form `3.5' specify a delay
per unit to tenths of milliseconds.
A number of escape sequences are provided in the string valued capa-
bilities for easy encoding of characters there. A \E maps to an
ESCAPE character, ^x maps to a control-x for any appropriate x, and
the sequences \n \r \t \b \f give a newline, return, tab, backspace
and formfeed. 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 null char-
acter in a string capability it must be encoded as \200. The rou-
tines which 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.
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 ex 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 ex. To easily test a new terminal description you can
set the environment variable TERMCAP to a pathname of a file con-
taining the description you are working on and the editor 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 the
editor. (This only works on version 7 systems.)
Basic capabilities
The number of columns on each line for the terminal is given by the
co numeric capability. If the terminal is a CRT, then the number of
lines on the screen is given by the li capability. If the terminal
wraps around to the beginning of the next line when it reaches the
right margin, then it should have the am capability. If the termi-
nal can clear its screen, then this is given by the cl string capa-
bility. If the terminal can backspace, then it should have the bs
capability, unless a backspace is accomplished by a character other
than ^H (ugh) in which case you should give this character as the bc
string capability. If it overstrikes (rather than clearing a posi-
tion when a character is struck over) then it should have the os
capability.
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A very important point here is that the local cursor motions encoded
in termcap are undefined at the left and top edges of a CRT termi-
nal. The editor will never attempt to backspace around the left
edge, nor will it attempt to go up locally off the top. The editor
assumes that feeding off the bottom of the screen will cause the
screen to scroll up, and the am capability tells whether the cursor
sticks at the right edge of the screen. If the terminal has switch
selectable automatic margins, the termcap file usually assumes that
this is on, i.e. am.
These capabilities suffice to describe hardcopy and "glass-tty" ter-
minals. Thus the model 33 teletype is described as
t3|33|tty33:co#72:os
while the Lear Siegler ADM-3 is described as
cl|adm3|3|lsi adm3:am:bs:cl=^Z:li#24:co#80
Cursor addressing
Cursor addressing in the terminal is described by a cm string capa-
bility, with printf(3s) like escapes %x in it. These substitute to
encodings of the current line or column position, while other char-
acters are passed through unchanged. If the cm string is thought of
as being a function, then its arguments are the line and then the
column to which motion is desired, and the % encodings have the fol-
lowing meanings:
%d as in printf, 0 origin
%2 like %2d
%3 like %3d
%. like %c
%+x adds x to value, then %.
%>xy if value > x adds y, no output.
%r reverses order of line and column, no output
%i increments line/column (for 1 origin)
%% gives a single %
%n exclusive or row and column with 0140 (DM2500)
%B BCD (16*(x/10)) + (x%10), no output.
%D Reverse coding (x-2*(x%16)), no output. (Delta Data).
Consider the HP2645, 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 rows and columns is inverted here, and that the row and
column are printed as two digits. Thus its cm capability is
"cm=6\E&%r%2c%2Y". The Microterm ACT-IV needs the current row and
column sent preceded by a ^T, with the row and column simply encoded
in binary, "cm=^T%.%.". Terminals which use "%." need to be able to
backspace the cursor (bs or bc), and to move the cursor up one line
on the screen (up introduced below). This is necessary because it
is not always safe to transmit \t, \n ^D and \r, as the system may
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change or discard them.
A final example is the LSI ADM-3a, which uses row and column offset
by a blank character, thus "cm=\E=%+ %+ ".
Cursor motions
If the terminal can move the cursor one position to the right, leav-
ing the character at the current position unchanged, then this
sequence should be given as nd (non-destructive space). If it can
move the cursor up a line on the screen in the same column, this
should be given as up. If the terminal has no cursor addressing
capability, but can home the cursor (to very upper left corner of
screen) then this can be given as ho; similarly a fast way of get-
ting to the lower left hand corner can be given as ll; this may
involve going up with up from the home position, but the editor will
never do this itself (unless ll does) because it makes no assumption
about the effect of moving up from the home position.
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, then this should be given as cd. The editor only
uses cd from the first column of a line.
Insert/delete line
If the terminal can open a new blank line before the line where the
cursor is, this should be given as al; this is done only from the
first position of a line. The cursor must then appear on the newly
blank line. If the terminal can delete the line which the cursor is
on, then this should be given as dl; this is done only from the
first position on the line to be deleted. If the terminal can
scroll the screen backwards, then this can be given as sb, but just
al suffices. If the terminal can retain display memory above then
the da capability should be given; if display memory can be retained
below then db should be given. These let the editor understand that
deleting a line on the screen may bring non-blank lines up from
below or that scrolling back with sb may bring down non-blank lines.
Insert/delete character
There are two basic kinds of intelligent terminals with respect to
insert/delete character which can be described using termcap. The
most common insert/delete character operations affect only the char-
acters on the current line and shift characters off the end of the
line rigidly. Other terminals, such as the Concept 100 and the Per-
kin 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
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untyped blanks. You can find out which kind of terminal you have by
clearing the screen and 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, you have the second type of terminal, and should
give the capability in, which stands for "insert null". If your
terminal does something different and unusual then you may have to
modify the editor to get it to use the insert mode your terminal
defines. We have seen no terminals which have an insert mode not
not falling into one of these two classes.
The editor can handle both terminals which have an insert mode, and
terminals which send a simple sequence to open a blank position on
the current line. Give as im the sequence to get into insert mode,
or give it an empty value if your terminal uses a sequence to insert
a blank position. Give as ei the sequence to leave insert mode
(give this, with an empty value also if you gave im so). Now give
as ic any sequence needed to be sent just before sending the charac-
ter to be inserted. Most terminals with a true insert mode will not
give ic, terminals which send a sequence to open a screen position
should give it here. (Insert mode is preferable to the sequence to
open a position on the screen if your terminal has both.) If post
insert padding is needed, give this as a number of milliseconds in
ip (a string option). Any other sequence which may need to be sent
after an insert of a single character may also be given in ip.
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 delete mode by giving dm and ed to enter
and exit delete mode, and dc to delete a single character while in
delete mode.
Highlighting, underlining, and visible bells
If your terminal has sequences to enter and exit standout mode these
can be given as so and se respectively. If there are several fla-
vors of standout mode (such as inverse video, blinking, or underlin-
ing - half bright is not usually an acceptable "standout" mode
unless the terminal is in inverse video mode constantly) the pre-
ferred mode is inverse video by itself. If the code to change into
or out of standout mode leaves one or even two blank spaces on the
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screen, as the TVI 912 and Teleray 1061 do, then ug should be given
to tell how many spaces are left.
Codes to begin underlining and end underlining can be given as us
and ue respectively. If the terminal has a code to underline the
current character and move the cursor one space to the right, such
as the Microterm Mime, this can be given as uc. (If the underline
code does not move the cursor to the right, give the code followed
by a nondestructive space.)
Many terminals, such as the HP 2621, automatically leave standout
mode when they move to a new line or the cursor is addressed. Pro-
grams using standout mode should exit standout mode before moving
the cursor or sending a newline.
If the terminal has a way of flashing the screen to indicate an
error quietly (a bell replacement) then this can be given as vb; it
must not move the cursor. If the terminal should be placed in a
different mode during open and visual modes of ex, this can be given
as vs and ve, sent at the start and end of these modes respectively.
These can be used to change, e.g., from a underline to a block cur-
sor and back.
If the terminal needs to be in a special mode when running a program
that addresses the cursor, 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 one screen-sized window must be fixed into the
terminal for cursor addressing to work properly.
If your terminal correctly generates 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, then 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 (this
applies, for example, to the unshifted HP 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. If there are other keys that transmit the same code as the ter-
minal expects for the corresponding function, such as clear screen,
the termcap 2 letter codes can be given in the ko capability, for
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example, ":ko=cl,ll,sf,sb:", which says that the terminal has clear,
home down, scroll down, and scroll up keys that transmit the same
thing as the cl, ll, sf, and sb entries.
The ma entry is also used to indicate arrow keys on terminals which
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, 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
be :ma=^Kj^Zk^Xl: indicating arrow keys left (^H), down (^K), up
(^Z), and right (^X). (There is no home key on the mime.)
Miscellaneous
If the terminal requires other than a null (zero) character as a
pad, then this can be given as pc.
If tabs on the terminal require padding, or if the terminal uses a
character other than ^I to tab, then this can be given as ta.
Hazeltine terminals, which don't allow `~' characters to be printed
should indicate hz. Datamedia terminals, which echo carriage-return
linefeed for carriage return and then ignore a following linefeed
should indicate nc. Early Concept terminals, which ignore a
linefeed immediately after an am wrap, should indicate xn. If an
erase-eol is required to get rid of standout (instead of merely
writing on top of it), xs should be given. Teleray terminals, where
tabs turn all characters moved over to blanks, should indicate xt.
Other specific terminal problems may be corrected by adding more
capabilities of the form xx.
Other capabilities include is, an initialization string for the ter-
minal, and if, the name of a file containing long initialization
strings. These strings are expected to properly clear and then set
the tabs on the terminal, if the terminal has settable tabs. If
both are given, is will be printed before if. This is useful where
if is /usr/lib/tabset/std but is clears the tabs first.
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 capa-
bility must be last and the combined length of the two entries must
not exceed 1024. Since termlib routines search the entry from left
to right, and since the tc capability is replaced by the correspond-
ing entry, the capabilities given at the left override the ones in
the similar terminal. A capability can be cancelled with xx@ where
xx is the capability. For example, the entry
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hn|2621nl:ks@:ke@:tc=2621:
defines a 2621nl that does not have the ks or ke capabilities, and
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), curses(3), termcap(3), tset(1), vi(1), ul(1), more(1)
AUTHOR
William Joy
Mark Horton added underlining and keypad support
BUGS
Ex allows only 256 characters for string capabilities, and the rou-
tines in termcap(3) do not check for overflow of this buffer. The
total length of a single entry (excluding only escaped newlines) may
not exceed 1024.
The ma, vs, and ve entries are specific to the vi program.
Not all programs support all entries. There are entries that are
not supported by any program.
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