Table of Contents

representative of what a terminfo entry for a modern terminal typically looks like.
ansi|ansi/pc-term compatible with color,
mc5i,
colors#8, ncv#3, pairs#64,
cub=\E[%p1%dD, cud=\E[%p1%dB, cuf=\E[%p1%dC, cuu=\E[%p1%dA, dch=\E[%p1%dP, dl=\E[%p1%dM, ech=\E[%p1%dX, el1=\E[1K, hpa=\E[%p1%dG, ht=\E[I, ich=\E[%p1%d@, il=\E[%p1%dL, indn=\E[%p1%dS, kbs=^H, kcbt=\E[Z, kcub1=\E[D, kcud1=\E[B, kcuf1=\E[C, kcuu1=\E[A, kf1=\E[M, kf10=\E[V, kf11=\E[W, kf12=\E[X, kf2=\E[N, kf3=\E[O, kf4=\E[P, kf5=\E[Q, kf6=\E[R, kf7=\E[S, kf8=\E[T, kf9=\E[U, kich1=\E[L, mc4=\E[4i, mc5=\E[5i, nel=\r\E[S, op=\E[37;40m, rep=%p1%c\E[%p2%{1}%-%db,
rin=\E[%p1%dT, s0ds=\E(B, s1ds=\E)B, s2ds=\E*B, s3ds=\E+B, setab=\E[4%p1%dm, setaf=\E[3%p1%dm, setb=\E[4%?%p1%{1}%=%t4%e%p1%{3}%=%t6%e%p1%{4}%=%t1%e%p1%{6}%=%t3%e%p1%d%;m, setf=\E[3%?%p1%{1}%=%t4%e%p1%{3}%=%t6%e%p1%{4}%=%t1%e%p1%{6}%=%t3%e%p1%d%;m, sgr=\E[0;10%?%p1%t;7%;%?%p2%t;4%;%?%p3%t;7%;%?%p4%t;5%;%?%p6%t;1%;%?%p7%t;8%;%?%p8%t;11%;%?%p9%t;12%;m, sgr0=\E[0;10m, tbc=\E[2g, u6=\E[%d;%dR, u7=\E[6n, u8=\E[?%[;0123456789]c, u9=\E[c, vpa=\E[%p1%dd,

Entries may continue onto multiple lines by placing white space

at the beginning of each line except the first. Comments may be included on lines beginning with ``#''. Capabilities in terminfo 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 operations.

Types of Capabilities

All capabilities have names. For instance, the fact that ANSI-

standard terminals have automatic margins (i.e., an automatic return and line-feed when the end of a line is reached) is indi- cated by the capability am. Hence the description of ansi includes am. Numeric capabilities are followed by the character `#' and then the value. Thus cols, which indicates the number of columns the terminal has, gives the value `80' for ansi.

Finally, string valued capabilities, such as el (clear to end of

line sequence) are given by the two-character code, an `=', and then a string ending at the next following `,'.

A number of escape sequences are provided in the string valued

capabilities for easy encoding of characters there. Both \E and \e map to an ESCAPE character, ^x maps to a control-x for any appropriate x, and the sequences \n \l \r \t \b \f \s give a new- line, line-feed, return, tab, backspace, form-feed, and space.

Other escapes include \^ for ^, \\ for \, \, for comma, \: for :,

and \0 for null. (\0 will produce \200, which does not terminate a string but behaves as a null character on most terminals.)

Finally, characters may be given as three octal digits after a \.

A delay in milliseconds may appear anywhere in a string capabil-

ity, enclosed in $<..> brackets, as in el=\EK$<5>, and padding characters are supplied by tputs to provide this delay. The delay must be a number with at most one decimal place of preci- sion; it may be followed by suffixes `*' or `/' or both. 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. (In the case of insert char- acter, the factor is still the number of lines affected.) Nor- mally, padding is advisory if the device has the xon capability; it is used for cost computation but does not trigger delays. A `/' suffix indicates that the padding is mandatory and forces a delay of the given number of milliseconds even on devices for which xon is present to indicate flow control.

Sometimes individual capabilities must be commented out. To do

this, put a period before the capability name. For example, see the second ind in the example above.

Fetching Compiled Descriptions

If the environment variable TERMINFO is set, it is interpreted as

the pathname of a directory containing the compiled description you are working on. Only that directory is searched.

If TERMINFO is not set, the ncurses version of the terminfo

reader code will instead look in the directory $HOME/.terminfo for a compiled description. If it fails to find one there, and the environment variable TERMINFO_DIRS is set, it will interpret the contents of that variable as a list of colon- separated directories to be searched (an empty entry is interpreted as a command to search ). If no description is found in any of the

TERMINFO_DIRS directories, the fetch fails.

If neither TERMINFO nor TERMINFO_DIRS is set, the last place

tried will be the system terminfo directory, . (Neither the $HOME/.terminfo lookups nor TERMINFO_DIRS extensions are supported under stock System V terminfo/curses.)

Preparing Descriptions

We now outline how to prepare descriptions of terminals. The

most effective way to prepare a terminal description is by imi- tating the description of a similar terminal in terminfo and to build up a description gradually, using partial descriptions with vi or some other screen-oriented program to check that they are correct. Be aware that a very unusual terminal may expose defi- ciencies in the ability of the terminfo file to describe it or bugs in the screen-handling code of the test program.

To get the padding for insert line right (if the terminal manu-

facturer did not document it) a severe test is to edit /etc/passwd at 9600 baud, delete 16 or so lines from the middle of the screen, then hit the `u' key several times quickly. If the terminal messes up, more padding is usually needed. A simi- lar test can be used for insert character.

Basic Capabilities

The number of columns on each line for the terminal is given by

the cols numeric capability. If the terminal is a CRT, then the number of lines on the screen is given by the lines 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 terminal can clear its screen, leaving the cursor in the home position, then this is given by the clear string capability. If the terminal overstrikes (rather than clearing a position when a character is struck over) then 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 TEKTRONIX 4010 series, as well as 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, control M.)

If there is a code to produce an audible signal (bell, beep, etc)

give this as bel.

If there is a code to move the cursor one position to the left

(such as backspace) that capability should be given as cub1.

Similarly, codes to move to the right, up, and down should be

given as cuf1, cuu1, and cud1. These local cursor motions should not alter the text they pass over, for example, you would not normally use `cuf1= ` because the space would erase the character moved over.

A very important point here is that the local cursor motions

encoded in terminfo are undefined at the left and top edges of a

CRT terminal. Programs should never attempt to backspace around

the left edge, unless bw is given, and never attempt to go up locally off the top. In order to scroll text up, a program will go to the bottom left corner of the screen and send the ind (index) string.

To scroll text down, a program goes to the top left corner of the

screen and sends the ri (reverse index) string. The strings ind and ri are undefined when not on their respective corners of the screen.

Parameterized versions of the scrolling sequences are indn and

rin which have the same semantics as ind and ri except that they take one parameter, and scroll that many lines. They are also undefined except at the appropriate edge of the screen.

The am capability tells whether the cursor sticks at the right

edge of the screen when text is output, but this does not neces- sarily apply to a cuf1 from the last column. The only local motion which is defined from the left edge is if bw is given, then a cub1 from the left edge will move to the right edge of the previous row. If bw is not given, the effect is undefined. This is useful for drawing a box around the edge of the screen, for example. If the terminal has switch selectable automatic mar- gins, the terminfo file usually assumes that this is on; i.e., am. If the terminal has a command which moves to the first col- umn of the next line, that command can be given as nel (newline).

It does not matter if the command clears the remainder of the

current line, so if the terminal has no cr and lf it may still be possible to craft a working nel out of one or both of them.

These capabilities suffice to describe hard-copy and «glass-tty"

terminals. Thus the model 33 teletype is described as 33|tty33|tty|model 33 teletype,
bel=^G, cols#72, cr=^M, cud1=^J, hc, ind=^J, os, while the Lear Siegler ADM-3 is described as adm3|3|lsi adm3,
am, bel=^G, clear=^Z, cols#80, cr=^M, cub1=^H, cud1=^J, ind=^J, lines#24,

Parameterized Strings

Cursor addressing and other strings requiring parameters in the

terminal are described by a parameterized string capability, with printf(3S) like escapes %x in it. For example, to address the cursor, the cup capability is given, using two parameters: the row and column to address 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 mrcup.

The parameter mechanism uses a stack and special % codes to

manipulate it. Typically a sequence will push one of the parame- ters onto the stack and then print it in some format. Often more complex operations are necessary.

The % encodings have the following meanings:

%%
outputs `%'
%d
print pop() as in printf
%2d
print pop() like %2d
%3d
print pop() like %3d %02d
%03d
as in printf
%x
print pop() as in printf
%2x
print pop() like %2x
%3x
print pop() like %3x %02x
%03x
as in printf
%c
print pop() gives %c
%s
print pop() gives %s
%p[1-9]
push i'th parm
%P[a-z]
set variable [a-z] to pop()
%g[a-z]
get variable [a-z] and push it
%'c'
char constant c
%{nn}
integer constant nn

%+ %- %* %/ %m
arithmetic (%m is mod): push(pop() op pop()) %& %| %^ bit operations: push(pop() op pop()) %= %> %< logical operations: push(pop() op pop())

%A, %O
logical and & or operations (for conditionals)
%! %~
unary operations push(op pop())
%i
add 1 to first two parms (for ANSI terminals)

%? expr %t thenpart %e elsepart %;
if-then-else, %e elsepart is optional. else-if's are possible a la Algol 68: %? c1 %t b1 %e c2 %t b2 %e c3 %t b3 %e c4 %t b4 %e %; ci are conditions, bi are bodies.

Binary operations are in postfix form with the operands in the

usual order. That is, to get x-5 one would use «%gx%{5}%-". %P and %g variables are persistent across escape-string evaluations.

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 cup capability is «cup=6\E&%p2%2dc%p1%2dY".

The Microterm ACT-IV needs the current row and column sent pre-

ceded by a ^T, with the row and column simply encoded in binary, «cup=^T%p1%c%p2%c". Terminals which use «%c» need to be able to backspace the cursor (cub1), and to move the cursor up one line on the screen (cuu1). This is necessary because it is not always safe to transmit \n ^D and \r, as the system may change or dis- card them. (The library routines dealing with terminfo set tty modes so that tabs are never expanded, so \t is safe to send.

This turns out to be essential for the Ann Arbor 4080.)

A final example is the LSI ADM-3a, which uses row and column off-

set by a blank character, thus «cup=\E=%p1%' `%+%c%p2%' `%+%c".

After sending `\E=', this pushes the first parameter, pushes the

ASCII value for a space (32), adds them (pushing the sum on the

stack in place of the two previous values) and outputs that value as a character. Then the same is done for the second parameter.

More complex arithmetic is possible using the stack.

If the terminal has row or column absolute cursor addressing,

these can be given as single parameter capabilities hpa (horizon- tal position absolute) and vpa (vertical position absolute).

Sometimes these are shorter than the more general two parameter

sequence (as with the hp2645) and can be used in preference to cup . If there are parameterized local motions (e.g., move n spaces to the right) these can be given as cud, cub, cuf, and cuu with a single parameter indicating how many spaces to move.

These are primarily useful if the terminal does not have cup,

such as the TEKTRONIX 4025.

Cursor Motions

If the terminal has a fast way to home the cursor (to very upper

left corner of screen) then this can be given as home; similarly a fast way of getting to the lower left-hand corner can be given as ll; this may involve going up with cuu1 from the home posi- tion, 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 addressing to (0,0): to the top left corner of the screen, not of memory. (Thus, the \EH sequence on HP terminals cannot be used for home.)

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 el. If the terminal can clear from the current position to the end of the display, then this should be given as ed. Ed is only defined from the first column of a line. (Thus, it can be simu- lated by a request to delete a large number of lines, if a true ed is not available.)

Insert/delete line and vertical motions

If the terminal can open a new blank line before the line where

the cursor is, this should be given as il1; 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 dl1; this is done only from the first position on the line to be deleted.

Versions of il1 and dl1 which take a single parameter and insert

or delete that many lines can be given as il and dl. If the ter- minal has a settable scrolling region (like the vt100) the com- mand to set this can be described with the csr 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

csr on a properly chosen region; the sc and rc (save and restore cursor) commands may be useful for ensuring that your synthesized insert/delete string does not move the cursor. (Note that the ncurses(3X) library does this synthesis automatically, so you need not compose insert/delete strings for an entry with csr).

Yet another way to construct insert and delete might be to use a

combination of index with the memory-lock feature found on some terminals (like the HP-700/90 series, which however also has insert/delete).

Inserting lines at the top or bottom of the screen can also be

done using ri or ind on many terminals without a true insert/delete line, and is often faster even on terminals with those features.

The boolean non_dest_scroll_region should be set if each

scrolling window is effectively a view port on a screen-sized canvas. To test for this capability, create a scrolling region in the middle of the screen, write something to the bottom line, move the cursor to the top of the region, and do ri followed by dl1 or ind. If the data scrolled off the bottom of the region by the ri re-appears, then scrolling is non-destructive. System V and XSI Curses expect that ind, ri, indn, and rin will simulate destructive scrolling; their documentation cautions you not to define csr unless this is true. This curses implementation is more liberal and will do explicit erases after scrolling if ndstr is defined.

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 wind. The four parameters are the starting and ending lines in memory and the starting and ending columns in memory, in that order.

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 indicate that deleting a line or scrolling may bring non-blank lines up from below or that scrolling back with ri 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 terminfo.

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 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".

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.

Terminfo can describe both terminals which have an insert mode,

and terminals which send a simple sequence to open a blank posi- tion on the current line. Give as smir the sequence to get into insert mode. Give as rmir the sequence to leave insert mode.

Now give as ich1 any sequence needed to be sent just before send-

ing the character to be inserted. Most terminals with a true insert mode will not give ich1; terminals which send a sequence to open a screen position should give it here.

If your terminal has both, insert mode is usually preferable to

ich1. Technically, you should not give both unless the terminal actually requires both to be used in combination. Accordingly, some non-curses applications get confused if both are present; the symptom is doubled characters in an update using insert.

This requirement is now rare; most ich sequences do not require

previous smir, and most smir insert modes do not require ich1 before each character. Therefore, the new curses actually assumes this is the case and uses either rmir/smir or ich/ich1 as appropriate (but not both). If you have to write an entry to be used under new curses for a terminal old enough to need both, include the rmir/smir sequences in ich1.

If post insert padding is needed, give this as a number of mil-

liseconds 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. If your terminal needs both to be placed into an `insert mode' and a special code to precede each inserted charac- ter, then both smir/rmir and ich1 can be given, and both will be used. The ich capability, with one parameter, n, will repeat the effects of ich1 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 mir to speed up inserting in this case. Omitting mir will affect only speed.

Some terminals (notably Datamedia's) must not have mir because of

the way their insert mode works.

Finally, you can specify dch1 to delete a single character, dch

with one parameter, n, to delete n characters, and delete mode by giving smdc and rmdc to enter and exit delete mode (any mode the terminal needs to be placed in for dch1 to work).

A command to erase n characters (equivalent to outputting n

blanks without moving the cursor) can be given as ech with one parameter.

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 smso and rmso, respectively. 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 xmc should be given to tell how many spaces are left.

Codes to begin underlining and end underlining can be given as

smul and rmul respectively. If the terminal has a code to under- line the current character and move the cursor one space to the right, such as the Microterm Mime, this can be given as uc.

Other capabilities to enter various highlighting modes include

blink (blinking) bold (bold or extra bright) dim (dim or half- bright) invis (blanking or invisible text) prot (protected) rev (reverse video) sgr0 (turn off all attribute modes) smacs (enter alternate character set mode) and rmacs (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 modes,

this should be given as sgr (set attributes), taking 9 parame- ters. Each parameter is either 0 or 1, as the corresponding attribute is on or off. The 9 parameters are, in order: stand- out, underline, reverse, blink, dim, bold, blank, protect, alter- nate character set. Not all modes need be supported by sgr, only those for which corresponding separate attribute commands exist.

Terminals with the ``magic cookie'' glitch (xmc) deposit special

``cookies'' when they receive mode-setting sequences, which affect the display algorithm rather than having extra bits for each character. Some terminals, such as the HP 2621, automati- cally leave standout mode when they move to a new line or the cursor is addressed. Programs using standout mode should exit standout mode before moving the cursor or sending a newline, unless the msgr capability, asserting that it is safe to move in standout mode, is present.

If the terminal has a way of flashing the screen to indicate an

error quietly (a bell replacement) then this can be given as flash; 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 make, for example, a non-blinking underline into an easier to find block or blinking underline) give this sequence as cvvis. If there is a way to make the cur- sor completely invisible, give that as civis. The capability cnorm should be given which undoes the effects of both of these modes.

If the terminal needs to be in a special mode when running a pro-

gram that uses these capabilities, the codes to enter and exit this mode can be given as smcup and rmcup. 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. This is also used for the TEKTRONIX 4025, where smcup sets the command character to be the one used by terminfo.

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 Handling

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 smkx and rmkx. 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 kcub1, kcuf1, kcuu1, kcud1, and khome respectively. If there are function keys such as f0, f1, ..., f10, the codes they send can be given as kf0, kf1, ..., kf10. If these keys have labels other than the default f0 through f10, the labels can be given as lf0, lf1, ..., lf10. The codes transmitted by certain other special keys can be given: kll (home down), kbs (backspace), ktbc (clear all tabs), kctab (clear the tab stop in this column), kclr (clear screen or erase key), kdch1 (delete character), kdl1 (delete line), krmir (exit insert mode), kel (clear to end of line), ked (clear to end of screen), kich1 (insert character or enter insert mode), kil1 (insert line), knp (next page), kpp (previous page), kind (scroll forward/down), kri (scroll backward/up), khts (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, the other five keys can be given as ka1, ka3, kb2, kc1, and kc3. These keys are useful when the effects of a 3 by 3 directional pad are needed.

Tabs and Initialization

If the terminal has hardware tabs, the command to advance to the

next tab stop can be given as ht (usually control I). A ``back- tab'' command which moves leftward to the next tab stop can be given as cbt. By convention, if the teletype modes indicate that tabs are being expanded by the computer rather than being sent to the terminal, programs should not use ht or cbt even if they are present, since the user may not have the tab stops properly set.

If the terminal has hardware tabs which are initially set every n

spaces when the terminal is powered up, the numeric parameter it is given, showing the number of spaces the tabs are set to. This is normally used by the tset command to determine whether to set the mode for hardware tab expansion, and whether to set the tab stops. If the terminal has tab stops that can be saved in non- volatile memory, the terminfo description can assume that they are properly set.

Other capabilities include is1, is2, and is3, initialization

strings for the terminal, iprog, the path name of a program to be run to initialize the terminal, and if, the name of a file con- taining long initialization strings. These strings are expected to set the terminal into modes consistent with the rest of the terminfo 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: is1; is2; setting tabs using tbc and hts; if; running the program iprog; and finally is3. Most initialization is done with is2. Special terminal modes can be set up without duplicating strings by putting the common sequences in is2 and special cases in is1 and is3. A pair of sequences that does a harder reset from a totally unknown state can be analogously given as rs1, rs2, rf, and rs3, analogous to is2 and if. These strings are output by the reset program, which is used when the terminal gets into a wedged state. Commands are normally placed in rs2 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 is2, 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 there are commands to set and clear tab stops, they can be

given as tbc (clear all tab stops) and hts (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 is2 or if.

Delays and Padding

Many older and slower terminals don't support either XON/XOFF or

DTR handshaking, including hard copy terminals and some very

archaic CRTs (including, for example, DEC VT100s). These may require padding characters after certain cursor motions and screen changes.

If the terminal uses xon/xoff handshaking for flow control (that

is, it automatically emits ^S back to the host when its input buffers are close to full), set xon. This capability suppresses the emission of padding. You can also set it for memory-mapped console devices effectively that don't have a speed limit.

Padding information should still be included so that routines can

make better decisions about relative costs, but actual pad char- acters will not be transmitted.

If pb (padding baud rate) is given, padding is suppressed at baud

rates below the value of pb. If the entry has no padding baud rate, then whether padding is emitted or not is completely con- trolled by xon.

If the terminal requires other than a null (zero) character as a

pad, then this can be given as pad. Only the first character of the pad string is used.

Status Lines

Some terminals have an extra `status line' which is not normally

used by software (and thus not counted in the terminal's lines capability).

The simplest case is a status line which is cursor-addressable

but not part of the main scrolling region on the screen; the

Heathkit H19 has a status line of this kind, as would a 24-line

VT100 with a 23-line scrolling region set up on initialization.

This situation is indicated by the hs capability.

Some terminals with status lines need special sequences to access

the status line. These may be expressed as a string with single parameter tsl which takes the cursor to a given zero-origin col- umn on the status line. The capability fsl must return to the main-screen cursor positions before the last tsl. You may need to embed the string values of sc (save cursor) and rc (restore cursor) in tsl and fsl to accomplish this.

The status line is normally assumed to be the same width as the

width of the terminal. If this is untrue, you can specify it with the numeric capability wsl.

A command to erase or blank the status line may be specified as

dsl.

The boolean capability eslok specifies that escape sequences,

tabs, etc. work ordinarily in the status line.

The ncurses implementation does not yet use any of these capabil-

ities. They are documented here in case they ever become impor- tant.

Line Graphics

Many terminals have alternate character sets useful for forms-

drawing. Terminfo and curses build in support for the drawing characters supported by the VT100, with some characters from the

AT&T 4410v1 added. This alternate character set may be specified

by the acsc capability.
center expand; c l l c c l l c lw25 lw6 lw2 lw20.

Glyph ACSAsciiVT100 Name Name DefaultName upper

left cornerACS_ULCORNER+l lower left cornerACS_LLCORNER+m upper right cornerACS_URCORNER+k lower right cornerACS_LRCORNER+j tee pointing rightACS_LTEE+t tee pointing leftACS_RTEE+u tee pointing up ACS_BTEE+v tee pointing downACS_TTEE+w horizontal line

ACS_HLINE-q vertical line ACS_VLINE|x large plus or crossover-

ACS_PLUS+n scan line 1 ACS_S1 ~o scan line 9 ACS_S9 _s

diamond ACS_DIAMOND+` checker board (stip- ple)ACS_CKBOARD:a degree symbol ACS_DEGREE\f plus/minus

ACS_PLMINUS#g bullet ACS_BULLETo~ arrow pointing left-

ACS_LARROW<, arrow pointing rightACS_RARROW>+ arrow pointing dow-

nACS_DARROWv. arrow pointing upACS_UARROW^- board of square- sACS_BOARD#h lantern symbol ACS_LANTERN#I solid square block-

Acs_block#0

The best way to define a new device's graphics set is to add a

column to a copy of this table for your terminal, giving the character which (when emitted between smacs/rmacs switches) will be rendered as the corresponding graphic. Then read off the

VT100/your terminal character pairs right to left in sequence;

these become the ACSC string.

Color Handling

Most color terminals are either `Tektronix-like' or `HP-like'.

Tektronix-like terminals have a predefined set of N colors (where

N usually 8), and can set character-cell foreground and back-

ground characters independently, mixing them into N * N color- pairs. On HP-like terminals, the use must set each color pair up separately (foreground and background are not independently set- table). Up to M color-pairs may be set up from 2*M different colors. ANSI-compatible terminals are Tektronix-like.

Some basic color capabilities are independent of the color

method. The numeric capabilities colors and pairs specify the maximum numbers of colors and color-pairs that can be displayed simultaneously. The op (original pair) string resets foreground and background colors to their default values for the terminal.

The oc string resets all colors or color-pairs to their default

values for the terminal. Some terminals (including many PC ter- minal emulators) erase screen areas with the current background color rather than the power-up default background; these should have the boolean capability bce.

To change the current foreground or background color on a Tek-

tronix-type terminal, use setaf (set ANSI foreground) and setab (set ANSI background) or setf (set foreground) and setb (set background). These take one parameter, the color number. The

SVr4 documentation describes only setaf/setab; the XPG4 draft

says that «If the terminal supports ANSI escape sequences to set background and foreground, they should be coded as setaf and setab, respectively. If the terminal supports other escape sequences to set background and foreground, they should be coded as setf and setb, respectively. The vidputs() function and the refresh functions use setaf and setab if they are defined."

The setaf/setab and setf/setb capabilities take a single numeric

argument each. Argument values 0-7 are portably defined as fol- lows (the middle column is the symbolic #define available in the header for the curses or ncurses libraries). The terminal hard- ware is free to map these as it likes, but the RGB values indi- cate normal locations in color space.
center; l c c c l l n l. Color #define ValueRGB black COLOR_BLACK00, 0, 0 red COLOR_RED 1max,0,0 green COLOR_GREEN20,max,0
yellow COLOR_YELLOW3max,max,0 blue COLOR_BLUE40,0,max magenta COLOR_MAGENTA5max,0,max cyan COLOR_CYAN60,max,max white COLOR_WHITE7max,max,max

On an HP-like terminal, use scp with a color-pair number parame-

ter to set which color pair is current.

On a Tektronix-like terminal, the capability ccc may be present

to indicate that colors can be modified. If so, the initc capa- bility will take a color number (0 to colors - 1)and three more parameters which describe the color. These three parameters default to being interpreted as RGB (Red, Green, Blue) values.

If the boolean capability hls is present, they are instead as HLS

(Hue, Lightness, Saturation) indices. The ranges are terminal- dependent.

On an HP-like terminal, initp may give a capability for changing

a color-pair value. It will take seven parameters; a color-pair number (0 to max_pairs - 1), and two triples describing first background and then foreground colors. These parameters must be (Red, Green, Blue) or (Hue, Lightness, Saturation) depending on hls.

On some color terminals, colors collide with highlights. You can

register these collisions with the ncv capability. This is a bit-mask of attributes not to be used when colors are enabled.

The correspondence with the attributes understood by curses is as

follows:
center; l c c lw25 lw2 lw10. Attribute BitDecimal

A_standout 01 A_underline 12 A_reverse 24 A_blink

38 A_DIM 416 A_BOLD 532 A_INVIS 664

A_protect 7128 A_altcharset 8256

For example, on many IBM PC consoles, the underline attribute

collides with the foreground color blue and is not available in color mode. These should have an ncv capability of 2.

Miscellaneous

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 hard-copy terminals. If a hard-copy terminal can eject to the next page (form feed), give this as ff (usually control 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 rep. The first parameter is the character to be repeated and the second is the number of times to repeat it. Thus, tparm(repeat_char, `x', 10) is the same as `xxxxxxxxxx'.

If the terminal has a settable command character, such as the

TEKTRONIX 4025, this can be indicated with cmdch. A prototype

command character is chosen which is used in all capabilities.

This character is given in the cmdch 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 with the character in the environment variable.

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 has a ``meta key'' which acts as a shift key,

setting the 8th bit of any character transmitted, 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 smm and rmm.

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. A value of lm#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 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 mc0: print the contents of the screen, mc4: turn off the printer, and mc5: 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 vari- ation mc5p 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 mc4, is transparently passed to the printer while an mc5p is in effect.

Strings to program function keys can be given as pfkey, pfloc,

and pfx. Each of these strings takes two parameters: the func- tion key number to program (from 0 to 10) and the string to pro- gram it with. Function key numbers out of this range may program undefined keys in a terminal dependent manner. The difference between the capabilities is that pfkey causes pressing the given key to be the same as the user typing the given string; pfloc causes the string to be executed by the terminal in local; and pfx causes the string to be transmitted to the computer.

Glitches and Braindamage

Hazeltine terminals, which do not allow `~' characters to be dis-

played should indicate hz.

Terminals which ignore a line-feed immediately after an am wrap,

such as the Concept and vt100, should indicate xenl.

If el is required to get rid of standout (instead of merely writ-

ing normal text on top of it), xhp should be given.

Teleray terminals, where tabs turn all characters moved over to

blanks, should indicate xt (destructive tabs). Note: the vari- able indicating this is now `dest_tabs_magic_smso'; in older ver- sions, it was teleray_glitch. This glitch is also taken to mean that it is not possible to position the cursor on top of a ``magic cookie'', that to erase standout mode it is instead necessary to use delete and insert line. The ncurses implementa- tion ignores this glitch.

The Beehive Superbee, which is unable to correctly transmit the

escape or control C characters, has xsb, indicating that the f1 key is used for escape and f2 for control C. (Only certain

Superbees have this problem, depending on the ROM.) Note that in

older terminfo versions, this capability was called `bee- hive_glitch'; it is now `no_esc_ctl_c'.

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 use can be given with the name of the similar termi- nal. The capabilities given before use override those in the terminal type invoked by use. A capability can be canceled by placing xx@ to the left of the capability definition, where xx is the capability. For example, the entry
2621-nl, smkx@, rmkx@, use=2621,
defines a 2621-nl that does not have the smkx or rmkx capabili- ties, 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.

Pitfalls of Long Entries

Long terminfo entries are unlikely to be a problem; to date, no

entry has even approached terminfo's 4K string-table maximum.

Unfortunately, the termcap translations are much more strictly

limited (to 1K), thus termcap translations of long terminfo entries can cause problems.

The man pages for 4.3BSD and older versions of tgetent() instruct

the user to allocate a 1K buffer for the termcap entry. The entry gets null-terminated by the termcap library, so that makes the maximum safe length for a termcap entry 1k-1 (1023) bytes.

Depending on what the application and the termcap library being

used does, and where in the termcap file the terminal type that tgetent() is searching for is, several bad things can happen.

Some termcap libraries print a warning message or exit if they

find an entry that's longer than 1023 bytes; others don't; others truncate the entries to 1023 bytes. Some application programs allocate more than the recommended 1K for the termcap entry; oth- ers don't.

Each termcap entry has two important sizes associated with it:

before «tc» expansion, and after «tc» expansion. «tc» is the capability that tacks on another termcap entry to the end of the current one, to add on its capabilities. If a termcap entry doesn't use the «tc» capability, then of course the two lengths are the same.

The «before tc expansion» length is the most important one,

because it affects more than just users of that particular termi- nal. This is the length of the entry as it exists in /etc/termcap, minus the backslash-newline pairs, which tgetent() strips out while reading it. Some termcap libraries strip off the final newline, too (GNU termcap does not). Now suppose: * a termcap entry before expansion is more than 1023 bytes long,
* and the application has only allocated a 1k buffer, * and the termcap library (like the one in BSD/OS 1.1 and GNU) reads the whole entry into the buffer, no matter what its length, to see if it's the entry it wants, * and tgetent() is searching for a terminal type that either is the long entry, appears in the termcap file after the long entry, or doesn't appear in the file at all (so that tgetent() has to search the whole termcap file).

Then tgetent() will overwrite memory, perhaps its stack, and

probably core dump the program. Programs like telnet are partic- ularly vulnerable; modern telnets pass along values like the terminal type automatically. The results are almost as undesir- able with a termcap library, like SunOS 4.1.3 and Ultrix 4.4, that prints warning messages when it reads an overly long termcap entry. If a termcap library truncates long entries, like OSF/1 3.0, it is immune to dying here but will return incorrect data for the terminal.

The «after tc expansion» length will have a similar effect to the

above, but only for people who actually set TERM to that terminal type, since tgetent() only does «tc» expansion once it's found the terminal type it was looking for, not while searching.

In summary, a termcap entry that is longer than 1023 bytes can

cause, on various combinations of termcap libraries and applica- tions, a core dump, warnings, or incorrect operation. If it's too long even before «tc» expansion, it will have this effect even for users of some other terminal types and users whose TERM variable does not have a termcap entry.

When in -C (translate to termcap) mode, the ncurses implementa-

tion of tic(1) issues warning messages when the pre-tc length of a termcap translation is too long. The -c (check) option also checks resolved (after tc expansion) lengths.

Binary Compatibility

It is not wise to count on portability of binary terminfo entries

between commercial UNIX versions. The problem is that there are at least two versions of terminfo (under HP-UX and AIX) which diverged from System V terminfo after SVr1, and have added exten- sion capabilities to the string table that (in the binary format) collide with System V and XSI Curses extensions.

Extensions

The %x operator in parameterized strings is unique to the ncurses

implementation of tparm (it is required in order to support an unfortunate choice of initc format on the Linux console).

Some SVr4 curses implementations, and all previous to SVr4, don't

interpret the %A and %O operators in parameter strings.

SVr4/XPG4 do not specify whether msgr licenses movement while in

an alternate-character-set mode (such modes may, among other things, map CR and NL to characters that don't trigger local motions). The ncurses implementation ignores msgr in ALTCHARSET mode. This raises the possibility that an XPG4 implementation making the opposite interpretation may need terminfo entries made for ncurses to have msgr turned off.

The ncurses library handles insert-character and insert-character

modes in a slightly non-standard way in order to get better update efficiency. See the Insert/Delete Character subsection above.

The parameter substitutions for set_clock and display_clock are

not documented in SVr4 or the XSI Curses standard. They are deduced from the documentation for the AT&T 505 terminal.

Be careful assigning the kmous capability. The ncurses wants to

interpret it as KEY_MOUSE, for use by terminals and emulators like xterm that can return mouse-tracking information in the key- board-input stream.

Different commercial ports of terminfo and curses support differ-

ent subsets of the XSI Curses standard and (in some cases) dif- ferent extension sets. Here is a summary, accurate as of October 1995:

SVR4, Solaris, ncurses -- These support all SVr4 capabilities.

SGI -- Supports the SVr4 set, adds one undocumented extended

string capability (set_pglen).

SVr1, Ultrix -- These support a restricted subset of terminfo

capabilities. The booleans end with xon_xoff; the numerics with width_status_line; and the strings with prtr_non.

HP/UX -- Supports the SVr1 subset, plus the SVr[234] numerics

num_labels, label_height, label_width, plus function keys 11 through 63, plus plab_norm, label_on, and label_off, plus some incompatible extensions in the string table.

AIX -- Supports the SVr1 subset, plus function keys 11 through

63, plus a number of incompatible string table extensions.

OSF -- Supports both the SVr4 set and the AIX extensions.

Files

/?/* files containing terminal descriptions

See Also

tic(1M) , curses(3X) , printf(3S) , term().

Authors

Zeyd M. Ben-Halim, Eric S. Raymond. Descends from the original

pcurses by Pavel Curtis.


Table of Contents