termcap.5

早期freebsd实现

(like the VT100),
the command to set this can be described with the
.Sy \&cs
capability,
which takes two parameters: the top and bottom lines of the scrolling region.
The cursor position is, alas, undefined after using this command.
It is possible to get the effect of insert or delete line
using this command \(em the
.Sy \&sc
and
.Sy \&rc
(save and restore cursor) commands are also useful.
Inserting lines at the top or bottom of the screen can also be done using
.Sy \&sr
or
.Sy \&sf
on many terminals without a true insert/delete line,
and is often faster even on terminals with those features.
.Pp
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
.Sy \&wi .
The four parameters are the starting and ending lines in memory
and the starting and ending columns in memory, in that order.
(This
.Xr terminfo
capability is described for completeness.
It is unlikely that any
.Nm termcap Ns \- using
program will support it.)
.Pp
If the terminal can retain display memory above the screen, then the
.Sy \&da
capability should be given;
if display memory can be retained
below, then
.Sy \&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
.Sy \&sr
may bring down non-blank lines.
.Ss Insert/Delete Character
There are two basic kinds of intelligent terminals with respect to
insert/delete character that can be described using
.Nm termcap .
The most common insert/delete character operations affect only the characters
on the current line and shift characters off the end of the line rigidly.
Other terminals, such as the Concept\-100 and the Perkin Elmer Owl, make
a distinction between typed and untyped blanks on the screen, shifting
upon an insert or delete only to an untyped blank on the screen which is
either eliminated or expanded to two untyped blanks.
You can determine
the kind of terminal you have by clearing the screen then typing
text separated by cursor motions.
Type
.Dq Li abc\ \ \ \ def
using local
cursor motions (not spaces) between the
.Dq abc
and the
.Dq def .
Then position the cursor before the
.Dq 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
.Dq abc
shifts over to the
.Dq def
which then move together around the end of the
current line and onto the next as you insert, then you have the second type of
terminal and should give the capability
.Sy \&in ,
which stands for
.Dq insert null .
While these are two logically separate attributes
(one line
.Em \&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.
.Pp
.Nm Termcap
can describe both terminals that have an insert mode and terminals
that send a simple sequence to open a blank position on the current line.
Give as
.Sy \&im
the sequence to get into insert mode.
Give as
.Sy \&ei
the sequence to leave insert mode.
Now give as
.Sy \&ic
any sequence that needs to be sent just before
each character to be inserted.
Most terminals with a true insert mode
will not give
.Sy \&ic ;
terminals that use a sequence to open a screen
position should give it here.
(If your terminal has both,
insert mode is usually preferable to
.Sy \&ic .
Do not give both unless the terminal actually requires both to be used
in combination.)
If post-insert padding is needed, give this as a number of milliseconds
in
.Sy \&ip
(a string option).
Any other sequence that may need to be
sent after insertion of a single character can also be given in
.Sy \&ip .
If your terminal needs to be placed into an `insert mode'
and needs a special code preceding each inserted character,
then both
.Sy \&im Ns / Sy \&ei
and
.Sy \&ic
can be given, and both will be used.
The
.Sy \&IC
capability, with one parameter
.Em n ,
will repeat the effects of
.Sy \&ic
.Em n
times.
.Pp
It is occasionally necessary to move around while in insert mode
to delete characters on the same line
.Pf ( Em 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
.Sy \&mi
to speed up inserting
in this case.
Omitting
.Sy \&mi
will affect only speed.
Some terminals
(notably Datamedia's) must not have
.Sy \&mi
because of the way their
insert mode works.
.Pp
Finally, you can specify
.Sy \&dc
to delete a single character,
.Sy \&DC
with one parameter
.Em n
to delete
.Em n
characters,
and delete mode by giving
.Sy \&dm
and
.Sy \&ed
to enter and exit delete mode
(which is any mode the terminal needs to be placed in for
.Sy \&dc
to work).
.Ss 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
.Em 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
.Sy \&so
and
.Sy \&se ,
respectively.
If the code to change into or out of standout
mode leaves one or even two blank spaces or garbage characters on the screen,
as the
.Tn TVI
912 and Teleray 1061 do,
then
.Sy \&sg
should be given to tell how many characters are left.
.Pp
Codes to begin underlining and end underlining can be given as
.Sy \&us
and
.Sy \&ue ,
respectively.
Underline mode change garbage is specified by
.Sy \&ug ,
similar to
.Sy \&sg .
If the terminal has a code to underline the current character and move
the cursor one position to the right,
such as the Microterm Mime,
this can be given as
.Sy \&uc .
.Pp
Other capabilities to enter various highlighting modes include
.Sy \&mb
(blinking),
.Sy \&md
(bold or extra bright),
.Sy \&mh
(dim or half-bright),
.Sy \&mk
(blanking or invisible text),
.Sy \&mp
(protected),
.Sy \&mr
(reverse video),
.Sy \&me
(turn off
.Em all
attribute modes),
.Sy \&as
(enter alternate character set mode), and
.Sy \&ae
(exit alternate character set mode).
Turning on any of these modes singly may or may not turn off other modes.
.Pp
If there is a sequence to set arbitrary combinations of mode,
this should be given as
.Sy \&sa
(set attributes), taking 9 parameters.
Each parameter is either 0 or 1,
as the corresponding attributes is on or off.
The 9 parameters are, in order: standout, underline, reverse, blink,
dim, bold, blank, protect, and alternate character set.
Not all modes need be supported by
.Sy \&sa ,
only those for which corresponding attribute commands exist.
(It is unlikely that a
.Nm termcap Ns \-using
program will support this capability, which is defined for compatibility
with
.Xr terminfo . )
.Pp
Terminals with the
.Dq magic cookie
glitches
.Pf ( Sy \&sg
and
.Sy \&ug ) ,
rather than maintaining extra attribute bits for each character cell,
instead deposit special
.Dq cookies ,
or
.Dq garbage characters ,,
when they receive mode-setting sequences,
which affect the display algorithm.
.Pp
Some terminals,
such as the Hewlett-Packard 2621,
automatically leave standout
mode when they move to a new line or when the cursor is addressed.
Programs using standout mode
should exit standout mode on such terminals
before moving the cursor or sending a newline.
On terminals where this is not a problem,
the
.Sy \&ms
capability should be present
to say that this overhead is unnecessary.
.Pp
If the terminal has
a way of flashing the screen to indicate an error quietly
(a bell replacement),
this can be given as
.Sy \&vb ;
it must not move the cursor.
.Pp
If the cursor needs to be made more visible than normal
when it is not on the bottom line
(to change, for example, a non-blinking underline into an easier-to-find
block or blinking underline),
give this sequence as
.Sy \&vs .
If there is a way to make the cursor completely invisible, give that as
.Sy \&vi .
The capability
.Sy \&ve ,
which undoes the effects of both of these modes,
should also be given.
.Pp
If your terminal correctly displays underlined characters
(with no special codes needed)
even though it does not overstrike,
then you should give the capability
.Sy \&ul .
If overstrikes are erasable with a blank,
this should be indicated by giving
.Sy \&eo .
.Ss Keypad
If the terminal has a keypad that transmits codes when the keys are pressed,
this information can be given.
Note that it is not possible to handle
terminals where the keypad only works in local mode
(this applies, for example, to the unshifted Hewlett-Packard 2621 keys).
If the keypad can be set to transmit or not transmit,
give these codes as
.Sy \&ks
and
.Sy \&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
.Sy \&kl ,
.Sy \&kr ,
.Sy \&ku ,
.Sy \&kd ,
and
.Sy \&kh ,
respectively.
If there are function keys such as f0, f1, ..., f9, the codes they send
can be given as
.Sy \&k0 ,
.Sy \&k1 ,
...,
.Sy \&k9 .
If these keys have labels other than the default f0 through f9, the labels
can be given as
.Sy \&l0 ,
.Sy \&l1 ,
...,
.Sy \&l9 .
The codes transmitted by certain other special keys can be given:
.Sy \&kH
(home down),
.Sy \&kb
(backspace),
.Sy \&ka
(clear all tabs),
.Sy \&kt
(clear the tab stop in this column),
.Sy \&kC
(clear screen or erase),
.Sy \&kD
(delete character),
.Sy \&kL
(delete line),
.Sy \&kM
(exit insert mode),
.Sy \&kE
(clear to end of line),
.Sy \&kS
(clear to end of screen),
.Sy \&kI
(insert character or enter insert mode),
.Sy \&kA
(insert line),
.Sy \&kN
(next page),
.Sy \&kP
(previous page),
.Sy \&kF
(scroll forward/down),
.Sy \&kR
(scroll backward/up), and
.Sy \&kT
(set a tab stop in this column).
In addition, if the keypad has a 3 by 3 array of keys
including the four arrow keys, then the other five keys can be given as
.Sy \&K1 ,
.Sy \&K2 ,
.Sy \&K3 ,
.Sy \&K4 ,
and
.Sy \&K5 .
These keys are useful when the effects of a 3 by 3 directional pad are needed.
The obsolete
.Sy \&ko
capability formerly used to describe
.Dq other
function keys has been
completely supplanted by the above capabilities.
.Pp
The
.Sy \&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
.Sy \&vi
which must be run on some minicomputers due to
memory limitations.
This field is redundant with
.Sy \&kl ,
.Sy \&kr ,
.Sy \&ku ,
.Sy \&kd ,
and
.Sy \&kh .
It consists of groups of two characters.
In each group, the first character is what an arrow key sends, and the
second character is the corresponding
.Sy \&vi
command.
These commands are
.Ar h
for
.Sy \&kl ,
.Ar j
for
.Sy \&kd ,
.Ar k
for
.Sy \&ku ,
.Ar l
for
.Sy \&kr ,
and
.Ar H
for
.Sy \&kh .
For example, the Mime would have
.Dq Li ma=^Hh^Kj^Zk^Xl
indicating arrow keys left (^H), down (^K), up (^Z), and right (^X).
(There is no home key on the Mime.)
.Ss Tabs and Initialization
If the terminal needs to be in a special mode when running
a program that uses these capabilities,
the codes to enter and exit this mode can be given as
.Sy \&ti
and
.Sy \&te .
This arises, for example, from terminals like the Concept with more than
one page of memory.
If the terminal has only memory-relative cursor addressing and not
screen-relative cursor addressing,
a screen-sized window must be fixed into
the display for cursor addressing to work properly.
This is also used for the Tektronix 4025, where
.Sy \&ti
sets the command character to be the one used by
.Nm termcap .
.Pp
Other capabilities
include
.Sy \&is ,
an initialization string for the terminal,
and
.Sy \&if ,
the name of a file containing long initialization strings.
These strings are expected to set the terminal into modes
consistent with the rest of the
.Nm termcap
description.
They are normally sent to the terminal by the
.Xr tset
program each time the user logs in.