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curs_inopts(3)                  Library calls                 curs_inopts(3)


NAME

       cbreak, echo, halfdelay, intrflush, is_cbreak, is_echo, is_nl, is_raw,
       keypad, meta, nl, nocbreak, nodelay, noecho, nonl, noqiflush, noraw,
       notimeout, qiflush, raw, timeout, wtimeout, typeahead - get and set
       curses terminal input options


SYNOPSIS

       #include <curses.h>

       int cbreak(void);
       int nocbreak(void);

       int echo(void);
       int noecho(void);

       int intrflush(WINDOW *win, bool bf);
       int keypad(WINDOW *win, bool bf);
       int meta(WINDOW *win, bool bf);
       int nodelay(WINDOW *win, bool bf);
       int notimeout(WINDOW *win, bool bf);

       int nl(void);
       int nonl(void);

       int raw(void);
       int noraw(void);

       void qiflush(void);
       void noqiflush(void);

       int halfdelay(int tenths);
       void timeout(int delay);
       void wtimeout(WINDOW *win, int delay);

       int typeahead(int fd);

       /* extensions */
       int is_cbreak(void);
       int is_echo(void);
       int is_nl(void);
       int is_raw(void);


DESCRIPTION

       ncurses provides several functions that let an application change the
       way input from the terminal is handled.  Some are global, applying to
       all windows.  Others apply only to a specific window.  Window-specific
       settings are not automatically applied to new or derived windows.  An
       application must apply these to each window if the same behavior is
       desired.

   cbreak, nocbreak
       Normally, the terminal driver buffers typed characters until a newline
       or carriage return is typed.  The cbreak routine disables line
       buffering and erase/kill character-processing (interrupt and flow
       control characters are unaffected), making characters typed by the user
       immediately available to the program.  The nocbreak routine returns the
       terminal to normal (cooked) mode.

       Initially the terminal may or may not be in cbreak mode, as the mode is
       inherited; therefore, a program should call cbreak or nocbreak
       explicitly.  Most interactive programs using curses set the cbreak
       mode.  Note that cbreak overrides raw.  [See curs_getch(3X) for a
       discussion of how these routines interact with echo and noecho.]

   echo, noecho
       The echo and noecho routines control whether characters typed by the
       user are echoed by getch(3X) as they are typed.  Echoing by the
       terminal driver is always disabled, but initially getch is in echo
       mode, so characters typed are echoed.  Authors of most interactive
       programs prefer to do their own echoing in a controlled area of the
       screen, or not to echo at all, so they disable echoing by calling
       noecho.  [See curs_getch(3X) for a discussion of how these routines
       interact with cbreak and nocbreak.]

   halfdelay
       The halfdelay routine is used for half-delay mode, which is similar to
       cbreak mode in that characters typed by the user are immediately
       available to the program.  However, after blocking for tenths tenths of
       seconds, ERR is returned if nothing has been typed.  The value of
       tenths must be a number between 1 and 255.  Use nocbreak to leave half-
       delay mode.

   intrflush
       If the intrflush option is enabled (bf is TRUE), and an interrupt key
       is pressed on the keyboard (interrupt, break, quit), all output in the
       terminal driver queue is flushed, giving the effect of faster response
       to the interrupt, but causing curses to have the wrong idea of what is
       on the screen.  Disabling the option (bf is FALSE), prevents the flush.
       The default for the option is inherited from the terminal driver
       settings.  The win argument is ignored.

   keypad
       The keypad option enables the keypad of the user's terminal.  If
       enabled (bf is TRUE), the user can press a function key (such as an
       arrow key) and wgetch(3X) returns a single value representing the
       function key, as in KEY_LEFT.  If disabled (bf is FALSE), curses does
       not treat function keys specially and the program has to interpret the
       escape sequences itself.  If the keypad in the terminal can be turned
       on (made to transmit) and off (made to work locally), turning on this
       option causes the terminal keypad to be turned on when wgetch(3X) is
       called.  The default value for keypad is FALSE.

   meta
       Initially, whether the terminal returns 7 or 8 significant bits on
       input depends on the control mode of the terminal driver [see
       termios(3)].  To force 8 bits to be returned, invoke meta(win, TRUE);
       this is equivalent, under POSIX, to setting the CS8 flag on the
       terminal.  To force 7 bits to be returned, invoke meta(win, FALSE);
       this is equivalent, under POSIX, to setting the CS7 flag on the
       terminal.  The window argument, win, is always ignored.  If the
       terminfo capabilities smm (meta_on) and rmm (meta_off) are defined for
       the terminal, smm is sent to the terminal when meta(win, TRUE) is
       called and rmm is sent when meta(win, FALSE) is called.

   nl, nonl
       The nl and nonl routines control whether the underlying display device
       translates the return key into newline on input.

   nodelay
       The nodelay option causes getch to be a non-blocking call.  If no input
       is ready, getch returns ERR.  If disabled (bf is FALSE), getch waits
       until a key is pressed.

   notimeout
       When interpreting an escape sequence, wgetch(3X) sets a timer while
       waiting for the next character.  If notimeout(win, TRUE) is called,
       then wgetch does not set a timer.  The purpose of the timeout is to
       distinguish sequences produced by a function key from those typed by a
       user.

   raw, noraw
       The raw and noraw routines place the terminal into or out of raw mode.
       Raw mode is similar to cbreak mode, in that characters typed are
       immediately passed through to the user program.  The differences are
       that in raw mode, the interrupt, quit, suspend, and flow control
       characters are all passed through uninterpreted, instead of generating
       a signal.  The behavior of the BREAK key depends on other bits in the
       terminal driver that are not set by curses.

   qiflush, nqiflush
       When the noqiflush routine is used, normal flush of input and output
       queues associated with the INTR, QUIT and SUSP characters will not be
       done [see termios(3)].  When qiflush is called, the queues will be
       flushed when these control characters are read.  You may want to call
       noqiflush in a signal handler if you want output to continue as though
       the interrupt had not occurred, after the handler exits.

   timeout, wtimeout
       The timeout and wtimeout routines set blocking or non-blocking read for
       a given window.  If delay is negative, a blocking read is used (i.e.,
       waits indefinitely for input).  If delay is zero, then a non-blocking
       read is used (i.e., read returns ERR if no input is waiting).  If delay
       is positive, then read blocks for delay milliseconds, and returns ERR
       if there is still no input.  Hence, these routines provide the same
       functionality as nodelay, plus the additional capability of being able
       to block for only delay milliseconds (where delay is positive).

   typeahead
       curses does "line-breakout optimization" by looking for typeahead
       periodically while updating the screen.  If input is found, and it is
       coming from a terminal, the current update is postponed until
       refresh(3X) or doupdate is called again.  This allows faster response
       to commands typed in advance.  Normally, the input FILE pointer passed
       to newterm, or stdin in the case that initscr was used, will be used to
       do this typeahead checking.  The typeahead routine specifies that the
       file descriptor fd is to be used to check for typeahead instead.  If fd
       is -1, then no typeahead checking is done.


RETURN VALUE

       All routines that return an integer return ERR upon failure and OK
       (SVr4 specifies only "an integer value other than ERR") upon successful
       completion, unless otherwise noted in the preceding routine
       descriptions.

       X/Open Curses does not specify any error conditions.  In this
       implementation, functions with a window parameter will return an error
       if it is null.  Any function will also return an error if the terminal
       was not initialized.  Also,

          halfdelay
               returns an error if its parameter is outside the range 1..255.


NOTES

       echo, noecho, halfdelay, intrflush, meta, nl, nonl, nodelay, notimeout,
       noqiflush, qiflush, timeout, and wtimeout may be implemented as macros.

       noraw and nocbreak follow historical practice in that they attempt to
       restore normal ("cooked") mode from raw and cbreak modes respectively.
       Mixing raw/noraw and cbreak/nocbreak calls leads to terminal driver
       control states that are hard to predict or understand; doing so is not
       recommended.


EXTENSIONS

       ncurses provides four "is_" functions that may be used to detect if the
       corresponding flags were set or reset.

                            Query       Set      Reset
                            ------------------------------
                            is_cbreak   cbreak   nocbreak
                            is_echo     echo     noecho
                            is_nl       nl       nonl
                            is_raw      raw      noraw

       In each case, the function returns

       1   if the flag is set,

       0   if the flag is reset, or

       -1  if the library is not initialized.

       They were designed for ncurses(3X), and are not found in SVr4 curses,
       4.4BSD curses, or any other previous curses implementation.


PORTABILITY

       Applications employing ncurses extensions should condition their use on
       the visibility of the NCURSES_VERSION preprocessor macro.

       Except as noted in section "EXTENSIONS" above, X/Open Curses, Issue 4,
       Version 2 describes these functions.

       ncurses follows X/Open Curses and the historical practice of AT&T
       curses implementations, in that the echo bit is cleared when curses
       initializes the terminal state.  BSD curses differed from this
       slightly; it left the echo bit on at initialization, but the BSD raw
       call turned it off as a side effect.  For best portability, set echo or
       noecho explicitly just after initialization, even if your program
       remains in cooked mode.

       X/Open Curses is ambiguous regarding whether raw should disable the
       CR/LF translations controlled by nl and nonl.  BSD curses did turn off
       these translations; AT&T curses (at least as late as SVr1) did not.
       ncurses does so, on the assumption that a programmer requesting raw
       input wants a clean (ideally, 8-bit clean) connection that the
       operating system will not alter.

       When keypad is first enabled, ncurses loads the key definitions for the
       current terminal description.  If the terminal description includes
       extended string capabilities, e.g., from using the -x option of tic,
       then ncurses also defines keys for the capabilities whose names begin
       with "k".  The corresponding keycodes are generated and (depending on
       previous loads of terminal descriptions) may differ from one execution
       of a program to the next.  The generated keycodes are recognized by the
       keyname(3X) function (which will then return a name beginning with "k"
       denoting the terminfo capability name rather than "K", used for curses
       key names).  On the other hand, an application can use define_key(3X)
       to establish a specific keycode for a given string.  This makes it
       possible for an application to check for an extended capability's
       presence with tigetstr, and reassign the keycode to match its own
       needs.

       Low-level applications can use tigetstr to obtain the definition of any
       particular string capability.  Higher-level applications which use the
       curses wgetch and similar functions to return keycodes rely upon the
       order in which the strings are loaded.  If more than one key definition
       has the same string value, then wgetch can return only one keycode.
       Most curses implementations (including ncurses) load key definitions in
       the order defined by the array of string capability names.  The last
       key to be loaded determines the keycode which will be returned.  In
       ncurses, you may also have extended capabilities interpreted as key
       definitions.  These are loaded after the predefined keys, and if a
       capability's value is the same as a previously-loaded key definition,
       the later definition is the one used.


HISTORY

       Formerly, ncurses used nl and nonl to control the conversion of
       newlines to carriage return/line feed on output as well as input.
       X/Open Curses documents the use of these functions only for input.
       This difference arose from converting the pcurses source (1986), which
       used ioctl(2) calls and the sgttyb structure, to termios (the POSIX
       terminal API).  In the former, both input and output were controlled
       via a single option CRMOD, while the latter separates these features.
       Because that conversion interferes with output optimization, ncurses
       6.2 (2020) amended nl and nonl to eliminate their effect on output.


SEE ALSO

       curses(3X), curs_getch(3X), curs_initscr(3X), curs_util(3X),
       define_key(3X), termios(3)

ncurses 6.5                       2024-04-13                   curs_inopts(3)

ncurses 6.5 - Generated Wed May 1 15:44:14 CDT 2024
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