termcap.5

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They will be printed in the following order:
.Sy \&is ;
setting tabs using
.Sy \&ct
and
.Sy \&st ;
and finally
.Sy \&if .
.Pf ( Xr Terminfo
uses
.Sy \&i\&1-i2
instead of
.Sy \&is
and runs the program
.Sy \&iP
and prints
.Sy "\&i\&3"
after the other initializations.)
A pair of sequences that does a harder reset from a totally unknown state
can be analogously given as
.Sy \&rs
and
.Sy \&if .
These strings are output by the
.Xr reset
program, which is used when the terminal gets into a wedged state.
.Pf ( Xr Terminfo
uses
.Sy "\&r1-r3"
instead of
.Sy \&rs . )
Commands are normally placed in
.Sy \&rs
and
.Sy \&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
.Sy \&is ,
but it causes an annoying glitch of the screen and is not normally needed
since the terminal is usually already in 80-column mode.
.Pp
If the terminal has hardware tabs,
the command to advance to the next tab stop can be given as
.Sy \&ta
(usually
.Sy \&^I ) .
A
.Dq backtab
command which moves leftward to the previous tab stop
can be given as
.Sy \&bt .
By convention,
if the terminal driver modes indicate that tab stops are being expanded
by the computer rather than being sent to the terminal,
programs should not use
.Sy \&ta
or
.Sy \&bt
even if they are present,
since the user may not have the tab stops properly set.
If the terminal has hardware tabs that are initially set every
.Ar n
positions when the terminal is powered up, then the numeric parameter
.Sy \&it
is given, showing the number of positions between tab stops.
This is normally used by the
.Xr tset
command to determine whether to set the driver mode for hardware tab
expansion, and whether to set the tab stops.
If the terminal has tab stops that can be saved in nonvolatile memory, the
.Nm termcap
description can assume that they are properly set.
.Pp
If there are commands to set and clear tab stops, they can be given as
.Sy \&ct
(clear all tab stops) and
.Sy \&st
(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
.Sy \&is
or
.Sy \&if .
.Ss Delays
Certain capabilities control padding in the terminal driver.
These are primarily needed by hardcopy terminals and are used by the
.Xr tset
program to set terminal driver modes appropriately.
Delays embedded in the capabilities
.Sy \&cr ,
.Sy \&sf ,
.Sy \&le ,
.Sy \&ff ,
and
.Sy \&ta
will cause the appropriate delay bits to be set in the terminal driver.
If
.Sy \&pb
(padding baud rate) is given, these values can be ignored at baud rates
below the value of
.Sy \&pb .
For
.Bx 4.2
.Xr tset ,
the delays are given as numeric capabilities
.Sy \&dC ,
.Sy \&dN ,
.Sy \&dB ,
.Sy \&dF ,
and
.Sy \&dT
instead.
.Ss Miscellaneous
If the terminal requires other than a
.Dv NUL
(zero) character as a pad,
this can be given as
.Sy \&pc .
Only the first character of the
.Sy \&pc
string is used.
.Pp
If the terminal has commands to save and restore the position of the
cursor, give them as
.Sy \&sc
and
.Sy \&rc .
.Pp
If the terminal has an extra
.Dq status line
that is not normally used by
software, this fact can be indicated.
If the status line is viewed as an extra line below the bottom line,
then the capability
.Sy \&hs
should be given.
Special strings to go to a position in the status line and to return
from the status line can be given as
.Sy \&ts
and
.Sy \&fs .
.Pf ( Xr \&fs
must leave the cursor position in the same place that it was before
.Sy \&ts .
If necessary, the
.Sy \&sc
and
.Sy \&rc
strings can be included in
.Sy \&ts
and
.Sy \&fs
to get this effect.)
The capability
.Sy \&ts
takes one parameter, which is the column number of the status line
to which the cursor is to be moved.
If escape sequences and other special commands such as tab work while in
the status line, the flag
.Sy \&es
can be given.
A string that turns off the status line (or otherwise erases its contents)
should be given as
.Sy \&ds .
The status line is normally assumed to be the same width as the
rest of the screen,
.Em i.e . ,
.Sy \&co .
If the status line is a different width (possibly because the terminal
does not allow an entire line to be loaded), then its width in columns
can be indicated with the numeric parameter
.Sy \&ws .
.Pp
If the terminal can move up or down half a line, this can be
indicated with
.Sy \&hu
(half-line up) and
.Sy \&hd
(half-line down).
This is primarily useful for superscripts and subscripts on hardcopy
terminals.
If a hardcopy terminal can eject to the next page (form feed),
give this as
.Sy \&ff
(usually
.Sy \&^L ) .
.Pp
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
.Sy \&rp .
The first parameter is the character to be repeated and the second is
the number of times to repeat it.
(This is a
.Xr terminfo
feature that is unlikely to be supported by a program that uses
.Nm termcap . )
.Pp
If the terminal has a settable command character, such as the
Tektronix 4025, this can be indicated with
.Sy \&CC .
A prototype command character is chosen which is used in all capabilities.
This character is given in the
.Sy \&CC
capability to identify it.
The following convention is supported on some
.Ux
systems:
The environment is to be searched for a
.Ev \&CC
variable,
and if found,
all occurrences of the prototype character are replaced by the character
in the environment variable.
This use of the
.Ev \&CC
environment variable
is a very bad idea, as it conflicts with
.Xr make 1 .
.Pp
Terminal descriptions that do not represent a specific kind of known
terminal, such as
.Em switch ,
.Em dialup ,
.Em patch ,
and
.Xr network ,
should include the
.Sy \&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
.Em virtual
terminal descriptions for which the escape sequences are known.)
.Pp
If the terminal uses xoff/xon
.Pq Tn DC3 Ns / Ns Tn DC1
handshaking for flow control, give
.Sy \&xo .
Padding information should still be included so that routines can make
better decisions about costs, but actual pad characters will not be
transmitted.
.Pp
If the terminal has a
.Dq meta key
which acts as a shift key, setting the
8th bit of any character transmitted, then this fact can be indicated with
.Sy \&km .
Otherwise, software will assume that the 8th bit is parity and it will
usually be cleared.
If strings exist to turn this
.Dq meta mode
on and off, they can be given as
.Sy \&mm
and
.Sy \&mo .
.Pp
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
.Sy \&lm .
An explicit value of 0 indicates that the number of lines is not fixed,
but that there is still more memory than fits on the screen.
.Pp
If the terminal is one of those supported by the
.Ux
system virtual
terminal protocol, the terminal number can be given as
.Sy \&vt .
.Pp
Media copy strings which control an auxiliary printer
connected to the terminal can be given as
.Sy \&ps :
print the contents of the screen;
.Sy \&pf :
turn off the printer; and
.Sy \&po :
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 variation
.Sy \&pO
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
.Sy \&pf ,
is transparently passed to the printer while
.Sy \&pO
is in effect.
.Pp
Strings to program function keys can be given as
.Sy \&pk ,
.Sy \&pl ,
and
.Sy \&px .
Each of these strings takes two parameters: the function key number
to program (from 0 to 9) and the string to program it with.
Function key numbers out of this range may program undefined keys
in a terminal-dependent manner.
The differences among the capabilities are that
.Sy \&pk
causes pressing the given key to be the same as the user typing the given
string;
.Sy \&pl
causes the string to be executed by the terminal in local mode;
and
.Sy \&px
causes the string to be transmitted to the computer.
Unfortunately, due to lack of a definition for string parameters in
.Nm termcap ,
only
.Xr terminfo
supports these capabilities.
.Ss Glitches and Braindamage
Hazeltine terminals, which do not allow `~' characters to be displayed,
should indicate
.Sy \&hz .
.Pp
The
.Sy \&nc
capability, now obsolete, formerly indicated Datamedia terminals,
which echo
.Sy \&\er \en
for
carriage return then ignore a following linefeed.
.Pp
Terminals that ignore a linefeed immediately after an
.Sy \&am
wrap, such as the Concept, should indicate
.Sy \&xn .
.Pp
If
.Sy \&ce
is required to get rid of standout
(instead of merely writing normal text on top of it),
.Sy \&xs
should be given.
.Pp
Teleray terminals, where tabs turn all characters moved over to blanks,
should indicate
.Sy \&xt
(destructive tabs).
This glitch is also taken to mean that it is not possible
to position the cursor on top of a \*(lqmagic cookie\*(rq, and that
to erase standout mode it is necessary to use delete and insert line.
.Pp
The Beehive Superbee, which is unable to correctly transmit the
.Dv ESC
or
.Sy \&^C
characters, has
.Sy \&xb ,
indicating that the
.Dq \&f\&1
key is used for
.Dv ESC
and
.Dq \&f\&2
for ^C.
(Only certain Superbees have this problem, depending on the
.Tn ROM . )
.Pp
Other specific terminal problems may be corrected by adding more
capabilities of the form
.Sy x Em x .
.Ss 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
.Sy \&tc
can be given
with the name of the similar terminal.
This capability must be
.Em last ,
and the combined length of the entries
must not exceed 1024.
The capabilities given before
.Sy \&tc
override those in the terminal type invoked by
.Sy \&tc .
A capability can be canceled by placing
.Sy \&xx@
to the left of the
.Sy \&tc
invocation, where
.Sy \&xx
is the capability.
For example, the entry
.Bd -literal -offset indent
hn\||\|2621\-nl:ks@:ke@:tc=2621:
.Ed
.Pp
defines a
.Dq 2621\-nl
that does not have the
.Sy \&ks
or
.Sy \&ke
capabilities,
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.
.Sh FILES
.Bl -tag -width /usr/share/misc/termcap.db -compact
.It Pa /usr/share/misc/termcap
File containing terminal descriptions.
.It Pa /usr/share/misc/termcap.db
Hash database file containing terminal descriptions (see 
.Xr cap_mkdb 1 ) .
.El
.Sh SEE ALSO
.Xr \&ex 1 ,
.Xr cap_mkdb 1 ,
.Xr more 1 ,
.Xr tset 1 ,
.Xr \&ul 1 ,
.Xr vi 1 ,
.Xr curses 3 ,
.Xr printf 3 ,
.Xr termcap 3 ,
.Xr term 7
.Sh CAVEATS AND BUGS
The
.Em Note :
.Nm termcap
functions
were replaced by
.Xr terminfo
in
.At V
Release 2.0.
The transition will be relatively painless if capabilities flagged as
.Dq obsolete
are avoided.
.Pp
Lines and columns are now stored by the kernel as well as in the termcap
entry.
Most programs now use the kernel information primarily; the information
in this file is used only if the kernel does not have any information.
.Pp
.Xr \&Vi
allows only 256 characters for string capabilities, and the routines
in
.Xr termlib 3
do not check for overflow of this buffer.
The total length of a single entry (excluding only escaped newlines)
may not exceed 1024.
.Pp
Not all programs support all entries.
.Sh HISTORY
The
.Nm
file format appeared in
.Bx 3 .