term% cat index.txt TERMCAP(5) File Formats 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 capa‐
bilities which they have, and by describing how operations are per‐
formed. 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 con‐
tain 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
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)
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 particu‐
lar 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 read‐
ability (here between the last field on a line and the first field on
the next). Capabilities in termcap are of three types: Boolean capa‐
bilities 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 operations.
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 line‐
feed when the end of a line is reached) is indicated by the capability
am. Hence the description of the Concept includes am. Numeric capa‐
bilities 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 a
string ending at the next following ‘:'. A delay in milliseconds may
appear after the ‘=' in such a capability, and padding characters 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 re‐
quired. When a ‘*' is specified, it is sometimes useful to give a de‐
lay of the form ‘3.5' specify a delay per unit to tenths of millisec‐
onds.
A number of escape sequences are provided in the string valued capabil‐
ities 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 se‐
quences \n \r \t \b \f give a newline, return, tab, backspace and form‐
feed. Finally, characters may be given as three octal digits after a
\, and the characters ^ and \ may be given as \^ and \\. If it is nec‐
essary to place a : in a capability it must be escaped in octal as
\072. If it is necessary to place a null character in a string capa‐
bility it must be encoded as \200. The routines which deal with term‐
cap 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 ef‐
fective way to prepare a terminal description is by imitating the de‐
scription of a similar terminal in termcap and to build up a descrip‐
tion gradually, using partial descriptions with ex to check that they
are correct. Be aware that a very unusual terminal may expose defi‐
ciencies 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 environ‐
ment variable TERMCAP to a pathname of a file containing the descrip‐
tion 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 mar‐
gin, then it should have the am capability. If the terminal can clear
its screen, then this is given by the cl string capability. 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 position when a character is struck
over) then it should have the os capability.
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 terminal. 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 feed‐
ing 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 mar‐
gins, the termcap file usually assumes that this is on, i.e. am.
These capabilities suffice to describe hardcopy and “glass-tty” termi‐
nals. 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 capabil‐
ity, with printf(3s) like escapes %x in it. These substitute to encod‐
ings of the current line or column position, while other characters 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 following 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 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, leaving
the character at the current position unchanged, then this sequence
should be given as nd (non-destructive space). If it can move the cur‐
sor 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 getting to the lower left hand corner
can be given as ll; this may involve going up with up from the home po‐
sition, but the editor will never do this itself (unless ll does) be‐
cause 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 dis‐
play, 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 back‐
wards, then this can be given as sb, but just al suffices. If the ter‐
minal 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 in‐
sert/delete character which 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 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 po‐
sition 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 mod‐
ify 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 se‐
quence needed to be sent just before sending the character to be in‐
serted. Most terminals with a true insert mode will not give ic, ter‐
minals 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 sin‐
gle 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 Datame‐
dia'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 flavors
of standout mode (such as inverse video, blinking, or underlining -
half bright is not usually an acceptable “standout” mode unless the
terminal is in inverse video mode constantly) the preferred mode is in‐
verse video by itself. If the code to change into or out of standout
mode leaves one or even two blank spaces on the 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 Mi‐
croterm 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 nondestruc‐
tive space.)
Many terminals, such as the HP 2621, automatically leave standout mode
when they move to a new line or the cursor is addressed. Programs us‐
ing 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 cursor 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 ad‐
dressing, 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 terminal expects for the correspond‐
ing function, such as clear screen, the termcap 2 letter codes can be
given in the ko capability, for 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 charac‐
ter is what an arrow key sends, the second character is the correspond‐
ing 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: indi‐
cating 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 char‐
acters moved over to blanks, should indicate xt. Other specific termi‐
nal problems may be corrected by adding more capabilities of the form
xx.
Other capabilities include is, an initialization string for the termi‐
nal, 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/tab‐
set/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 capability
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 corresponding entry, the ca‐
pabilities 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
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)
AUTHOR
William Joy
Mark Horton added underlining and keypad support
BUGS
Ex allows only 256 characters for string capabilities, and the routines
in termcap(3) do not check for overflow of this buffer. The total
length of a single entry (excluding only escaped newlines) may not ex‐
ceed 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.
5 5/10/80 TERMCAP(5)