termcap.5

<B>Digital的Unix操作系统VAX 4.2源码</B>

The Microterm 2ACT-IV needs the current row and column sent
preceded by a ^T, 
with the row and column simply encoded in binary,
``cm=^T%.%.''.
Terminals that use ``%.'' need to be able to
backspace the cursor (\f(CWbs\fR or \f(CWbc\fR),
and to move the cursor up
one line on the screen (\f(CWup\fR introduced in the following section).
This is necessary
because it is not always safe to transmit \f(CW\et\fR, \f(CW\en\fR
\f(CW^D\fR, and \f(CW\er\fR, as the system may change or discard them.
.PP
A final example is the LSI ADM-3a, which uses row and column
offset by a blank character; thus \*(lqcm=\eE=%+ %+ \*(rq.
.PP
.B Cursor Motions
.PP
If the terminal can move the cursor one position to the right, leaving
the character at the current position unchanged,
this sequence should
be given as \f(CWnd\fR (non-destructive space).  If it can move the cursor
up a line
on the screen in the same column, this should be given as \f(CWup\fR.
If the terminal has no cursor addressing capability,
but can home the cursor
(to very upper left corner of screen), this can be given as
\f(CWho\fR. Similarly a fast way of getting to the lower left hand corner
can be given as \f(CWll\fR. This may involve going up with \f(CWup\fR
from the home position,
but the editor will never do
this itself, unless \f(CWll\fR does, because it
makes no assumption about the effect of
moving up from the home position.
.PP
.B Area Clears
.PP
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 \f(CWce\fR.
If the terminal can clear from the current position to the end of the
display, this should be given as \f(CWcd\fR.
The editor only uses
\f(CWcd\fR from the first column of a line.
.PP
.B Insert/Delete Line
.PP
If the terminal can open a new
blank line before the line where the cursor
is, this should be given as \f(CWal\fR; 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, this
should be given as \f(CWdl\fR.
This is done only from the first position on
the line to be deleted.
If the terminal can scroll
the screen backwards, this can be given as
\f(CWsb\fR, but just \f(CWal\fR suffices.
If the terminal can retain display memory above, the
\f(CWda\fR capability should be given; if display memory can be retained
below, \f(CWdb\fR should be given.  These let the editor understand
that deleting a line on the
screen may bring nonblank lines up from below
or that scrolling back with \f(CWsb\fR may bring down nonblank lines.
.PP
.B Insert/Delete Character
.PP
There are two basic kinds of intelligent terminals with respect to
the insert/delete character that can be described using
.PN 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 2 untyped blanks.  You can find out
which kind of terminal you have by clearing the screen and typing
text separated by cursor motions.
Type \*(lqabc\ \ \ \ def\*(rq using local
cursor motions (not spaces) between
the \*(lqabc\*(rq and the \*(lqdef\*(rq.
Then, position the cursor before
the \*(lqabc\*(rq 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, your terminal does
not distinguish between blanks and untyped
positions.  If the \*(lqabc\*(rq
shifts over to the \*(lqdef\*(rq
and then moves with it around the end of the
current line and onto
the next line as you insert, you have the second type of
terminal, and should give the capability \f(CWin\fR, which stands for
\*(lqinsert null\*(rq.
If your terminal does something different and unusual,
you may have to modify the editor to get it to use the insert
mode your terminal defines.
Virtually all terminals that have an insert
mode fall into one of these two classes.
.PP
The editor can handle both terminals 
that have an insert mode and terminals
that send a simple sequence
to open a blank position on the current line.
Give as \f(CWim\fR 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 \f(CWei\fR the sequence to leave insert mode (give this with
an empty value also, if you gave \f(CWim\fR so).
Give as \f(CWic\fR any sequence needed to be sent just before sending
the character to be inserted.  Most terminals with a true insert mode
will not give \f(CWic\fR.  Terminals that 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 \f(CWip\fR (a string option).  Any other sequence that may need to be
sent after an insert of a single
character can also be given in \f(CWip\fR.
.PP
It is occasionally necessary to move around while in insert mode
to delete characters on the same line (for example, if there is a tab after
the insertion position).  If your terminal allows motion while in
insert mode, you can give the capability \f(CWmi\fR to speed up inserting
in this case.
Omitting \f(CWmi\fR affects only speed.   Some terminals
(notably Datamedia's) must not have \f(CWmi\fR because of the way their
insert mode works.
.PP
Finally, you can specify delete mode by giving \f(CWdm\fR and \f(CWed\fR
to enter and exit delete mode, and \f(CWdc\fR to delete a single character
while in delete mode.
.PP
.B "Highlighting, Underlining, and Visible Bells"
.PP
If your terminal has sequences to enter and exit standout mode, these
can be given as \f(CWso\fR and \f(CWse\fR, respectively.
If there are several kinds of standout mode,
such as inverse video, blinking, or underlining.
Half-bright is not usually an acceptable \*(lqstandout\*(rq mode,
unless the terminal is in inverse video mode constantly.
The preferred mode is inverse video by itself.
If the code to change into or out of standout
mode leaves 1 or even 2 blank spaces on the screen,
as the TVI 912 and Teleray 1061 do,
\f(CWug\fR should be given to tell how many spaces are left.
.PP
Codes to begin underlining and end underlining can be given as \f(CWus\fR
and \f(CWue\fR, 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 \f(CWuc\fR.
(If the underline code does not move the cursor to the right,
give the code followed by a nondestructive space.)
.PP
Many terminals, such as the HP 2621, automatically 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.
.PP
If the terminal has
a way of flashing the screen to indicate
an error quietly (a bell replacement),
this can be given as \f(CWvb\fR; it must not move the cursor.
If the terminal should be placed in a different mode during
open and visual modes of
.PN ex ,
this can be given as
\f(CWvs\fR and \f(CWve\fR, sent at the start and end of these modes
respectively.  These can be used to change, for example, from an underline
to a block cursor and back.
.PP
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 \f(CWti\fR and \f(CWte\fR.
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.
.PP
If your terminal correctly generates underlined characters,
with no special codes needed,
even though it does not overstrike,
you should give the capability \f(CWul\fR.
If overstrikes are erasable with a blank,
this should be indicated by giving \f(CWeo\fR.
.PP
.B Keypad
.PP
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 \f(CWks\fR and \f(CWke\fR.
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
\f(CWkl\fR, \f(CWkr\fR, \f(CWku\fR, \f(CWkd\fR, and \f(CWkh\fR,
respectively.
If there are function keys such as f0, f1, ..., f9, the codes they send
can be given as \f(CWk0\fR, \f(CWk1\fR, ..., \f(CWk9\fR.
If these keys have labels other than
the default f0 through f9, the labels
can be given as \f(CWl0\fR, \f(CWl1\fR, ..., \f(CWl9\fR.
If there are other keys that
transmit the same code as the terminal expects
for the corresponding function, such as clear screen, the 
.PN termcapP
2-letter codes can be given in the \f(CWko\fR capability,
for example, \*(lq:ko=cl,ll,sf,sb:\*(rq,
which says that the terminal has
clear, home down, scroll down, and scroll up keys that transmit
the same thing as the 
.PN cl , 
.PN ll , 
.PN sf , 
and 
.PN sb 
entries.
.PP
The
.PN ma
entry is also used to indicate arrow keys on terminals that have
single-character arrow keys.  It is obsolete, but still in use in
Version 2 of 
.PN vi ,
which must be run on some minicomputers due to
memory limitations.
This field is redundant with
\f(CWkl\fR, \f(CWkr\fR, \f(CWku\fR, \f(CWkd\fR, and \f(CWkh\fR.
It consists of groups of 2 characters.
In each group, the first character is what an arrow key sends; the
second character is the corresponding
.PN vi 
command.
These commands are
.PN h
for
.PN kl ,
.PN j
for
.PN kd ,
.PN k
for
.PN ku ,
.PN l
for
.PN kr ,
and
.PN H
for
.PN kh .
For example, the Microterm 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.)
.PP
.B Miscellaneous
.PP
If the terminal requires other than a null (zero) character as a pad,
this can be given as \f(CWpc\fR.
.PP
If tabs on the terminal require padding, or if the terminal uses a
character other than \f(CW^I\fR to tab,
this can be given as \f(CWta\fR.
.PP
Hazeltine terminals, which do not allow tildes (~)
to be printed, should indicate \f(CWhz\fR.
Datamedia terminals, which echo
carriage-return linefeed for a carriage return
and then ignore a following linefeed, should indicate \f(CWnc\fR.
Early Concept terminals,
which ignore a linefeed immediately after an \f(CWam\fR
wrap, should indicate \f(CWxn\fR.
If an erase-eol is required to get rid of standout
(instead of merely writing on top of it),
\f(CWxs\fP should be given.
Teleray terminals, where tabs turn all characters moved over to blanks,
should indicate \f(CWxt\fR.
Other specific terminal problems may be corrected by adding more
capabilities of the form \f(CWx\fIx\fR.
.PP
Other capabilities
include \f(CWis\fR, an initialization string for the terminal,
and \f(CWif\fR, 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, \f(CWis\fR is printed before \f(CWif\fR.
This is useful where \f(CWif\fR is
.PN /usr/lib/tabset/std
but \f(CWis\fR
clears the tabs first.
.PP
.B Similar Terminals
.PP
If there are two very similar terminals,
one can be defined as being just like the other with certain exceptions.
The string capability \f(CWtc\fR can be given
with the name of the similar terminal.
This capability must be \fIlast\fP and
the combined length of the two entries
must not exceed 1024. Since
.PN termlib
routines search the entry from left to right,
and since the tc capability is
replaced by the corresponding entry, the capabilities given at the left
override the ones in the similar terminal.
A capability can be canceled with \f(CWxx@\fR, where xx is the capability.
For example, the following entry
defines a 2621nl that does not have the
\f(CWks\fR or \f(CWke\fR capabilities,
and hence does not turn on the function key labels when in visual mode:
.EX
hn\||\|2621nl:ks@:ke@:tc=2621:
.EE
.PP
This is useful for different modes for a terminal or for different
user preferences.
.SH Restrictions
The
.PN vi
and
.PN ex
commands
allow only 256 characters for string capabilities, and the routines
in 
.MS termcap 3x
do not check for overflow of this buffer.
The total length of a single entry (excluding only escaped newlines)
cannot exceed 1024.
.PP
The
.PN ma ,
.PN vs ,
and
.PN ve
entries are specific to the 
.PN vi
program.
.SH Files
.TP 20
.PN /etc/termcap
File containing terminal descriptions
.SH See Also
ex(1), more(1), tset(1), ul(1), vi(1), curses(3x), termcap(3x)
.NXE "termcap file" "format"
.NXE "terminal" "creating capability data base"