инициализировать терминал или запросить базу данных terminfo (initialize a terminal or query terminfo database)
Описание (Description)
The @TPUT@
utility uses the terminfo
database to make the values
of terminal-dependent capabilities and information available to
the shell (see sh
(1)), to initialize or reset the terminal, or
return the long name of the requested terminal type. The result
depends upon the capability's type:
string
@TPUT@
writes the string to the standard output. No
trailing newline is supplied.
integer
@TPUT@
writes the decimal value to the standard output,
with a trailing newline.
boolean
@TPUT@
simply sets the exit code (0
for TRUE if the
terminal has the capability, 1
for FALSE if it does not),
and writes nothing to the standard output.
Before using a value returned on the standard output, the
application should test the exit code (e.g., $?
, see sh
(1)) to be
sure it is 0
. (See the EXIT CODES
and DIAGNOSTICS
sections.)
For a complete list of capabilities and the capname associated
with each, see terminfo(5).
Options
-S
allows more than one capability per invocation of @TPUT@
.
The capabilities must be passed to @TPUT@
from the
standard input instead of from the command line (see
example). Only one capname is allowed per line. The -S
option changes the meaning of the 0
and 1
boolean and
string exit codes (see the EXIT CODES section).
Because some capabilities may use string parameters rather
than numbers, @TPUT@
uses a table and the presence of
parameters in its input to decide whether to use
tparm
(3X), and how to interpret the parameters.
-T
type indicates the type of terminal. Normally this option is
unnecessary, because the default is taken from the
environment variable TERM
. If -T
is specified, then the
shell variables LINES
and COLUMNS
will also be ignored.
-V
reports the version of ncurses which was used in this
program, and exits.
-x
do not attempt to clear the terminal's scrollback buffer
using the extended 'E3' capability.
Commands
A few commands (init
, reset
and longname
) are special; they are
defined by the @TPUT@
program. The others are the names of
capabilities from the terminal database (see terminfo(5) for a
list). Although init
and reset
resemble capability names, @TPUT@
uses several capabilities to perform these special functions.
capname
indicates the capability from the terminal database.
If the capability is a string that takes parameters, the
arguments following the capability will be used as
parameters for the string.
Most parameters are numbers. Only a few terminal
capabilities require string parameters; @TPUT@
uses a
table to decide which to pass as strings. Normally @TPUT@
uses tparm
(3X) to perform the substitution. If no
parameters are given for the capability, @TPUT@
writes the
string without performing the substitution.
init
If the terminal database is present and an entry for the
user's terminal exists (see -T
type, above), the following
will occur:
(1) first, @TPUT@
retrieves the current terminal mode
settings for your terminal. It does this by
successively testing
• the standard error,
• standard output,
• standard input and
• ultimately '/dev/tty'
to obtain terminal settings. Having retrieved these
settings, @TPUT@
remembers which file descriptor to
use when updating settings.
(2) if the window size cannot be obtained from the
operating system, but the terminal description (or
environment, e.g., LINES
and COLUMNS
variables
specify this), update the operating system's notion
of the window size.
(3) the terminal modes will be updated:
• any delays (e.g., newline) specified in the entry
will be set in the tty driver,
• tabs expansion will be turned on or off according
to the specification in the entry, and
• if tabs are not expanded, standard tabs will be
set (every 8 spaces).
(4) if present, the terminal's initialization strings
will be output as detailed in the terminfo(5) section
on Tabs and Initialization,
(5) output is flushed.
If an entry does not contain the information needed for
any of these activities, that activity will silently be
skipped.
reset
This is similar to init
, with two differences:
(1) before any other initialization, the terminal modes
will be reset to a 'sane' state:
• set cooked and echo modes,
• turn off cbreak and raw modes,
• turn on newline translation and
• reset any unset special characters to their
default values
(2) Instead of putting out initialization strings, the
terminal's reset strings will be output if present
(rs1
, rs2
, rs3
, rf
). If the reset strings are not
present, but initialization strings are, the
initialization strings will be output.
Otherwise, reset
acts identically to init
.
longname
If the terminal database is present and an entry for the
user's terminal exists (see -T
type above), then the long
name of the terminal will be put out. The long name is
the last name in the first line of the terminal's
description in the terminfo
database [see term(5)].
Aliases
@TPUT@
handles the clear
, init
and reset
commands specially: it
allows for the possibility that it is invoked by a link with
those names.
If @TPUT@
is invoked by a link named reset
, this has the same
effect as @TPUT@ reset
. The @TSET@
(1) utility also treats a link
named reset
specially.
Before ncurses 6.1, the two utilities were different from each
other:
• @TSET@
utility reset the terminal modes and special
characters (not done with @TPUT@
).
• On the other hand, @TSET@
's repertoire of terminal
capabilities for resetting the terminal was more limited,
i.e., only reset_1string
, reset_2string
and reset_file
in
contrast to the tab-stops and margins which are set by this
utility.
• The reset
program is usually an alias for @TSET@
, because of
this difference with resetting terminal modes and special
characters.
With the changes made for ncurses 6.1, the reset feature of the
two programs is (mostly) the same. A few differences remain:
• The @TSET@
program waits one second when resetting, in case
it happens to be a hardware terminal.
• The two programs write the terminal initialization strings to
different streams (i.e., the standard error for @TSET@
and
the standard output for @TPUT@
).
Note:
although these programs write to different streams,
redirecting their output to a file will capture only part of
their actions. The changes to the terminal modes are not
affected by redirecting the output.
If @TPUT@
is invoked by a link named init
, this has the same
effect as @TPUT@ init
. Again, you are less likely to use that
link because another program named init
has a more well-
established use.
Terminal Size
Besides the special commands (e.g., clear
), @TPUT@ treats certain
terminfo capabilities specially: lines
and cols
. @TPUT@ calls
setupterm
(3X) to obtain the terminal size:
• first, it gets the size from the terminal database (which
generally is not provided for terminal emulators which do not
have a fixed window size)
• then it asks the operating system for the terminal's size
(which generally works, unless connecting via a serial line
which does not support NAWS: negotiations about window size).
• finally, it inspects the environment variables LINES
and
COLUMNS
which may override the terminal size.
If the -T
option is given @TPUT@ ignores the environment
variables by calling use_tioctl(TRUE)
, relying upon the operating
system (or finally, the terminal database).