curs_inopts(3x) — Linux manual page


curs_inopts(3X)                                          curs_inopts(3X)

NAME         top

       cbreak, nocbreak, echo, noecho, halfdelay, intrflush, keypad,
       meta, nl, nonl, nodelay, notimeout, raw, noraw, qiflush,
       noqiflush, timeout, wtimeout, typeahead - curses input options

SYNOPSIS         top

       #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);

DESCRIPTION         top

       The ncurses library provides several functions which 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 needed.

       Normally, the tty 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.]

       The echo and noecho routines control whether characters typed by
       the user are echoed by getch(3X) as they are typed.  Echoing by
       the tty 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

       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.

       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 tty driver queue will be 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 tty driver settings.  The window argument is

       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.

       Initially, whether the terminal returns 7 or 8 significant bits
       on input depends on the control mode of the tty 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.

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

       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.

       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 differentiate between sequences received from a
       function key and those typed by a user.

       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 tty driver that are not set by

       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.

       The timeout and wtimeout routines set blocking or non-blocking
       read for a given window.  If delay is negative, blocking read is
       used (i.e., waits indefinitely for input).  If delay is zero,
       then 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).

       The curses library does “line-breakout optimization” by looking
       for typeahead periodically while updating the screen.  If input
       is found, and it is coming from a tty, 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         top

       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 does not define 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,

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

PORTABILITY         top

       These functions are described in the XSI Curses standard, Issue

       The ncurses library obeys the XPG4 standard and the historical
       practice of the 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

       The XSI Curses standard is ambiguous on the question of whether
       raw should disable the CRLF translations controlled by nl and
       nonl.  BSD curses did turn off these translations; AT&T curses
       (at least as late as SVr1) did not.  We chose to do so, on the
       theory 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 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 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.

NOTES         top

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

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

SEE ALSO         top

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

COLOPHON         top

       This page is part of the ncurses (new curses) project.
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