Provided by: ncurses-doc_6.1+20190803-1ubuntu1_all bug

NAME

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

SYNOPSIS

       #include <curses.h>

       int cbreak(void);
       int nocbreak(void);
       int echo(void);
       int noecho(void);
       int halfdelay(int tenths);
       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 raw(void);
       int noraw(void);
       void noqiflush(void);
       void qiflush(void);
       int notimeout(WINDOW *win, bool bf);
       void timeout(int delay);
       void wtimeout(WINDOW *win, int delay);
       int typeahead(int fd);

DESCRIPTION

       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.

   cbreak
       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  getch(3NCURSES)
       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 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 getch(3NCURSES) 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 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 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 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.

   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.

       While interpreting an input 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.

   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 tty  driver  that  are
       not set by curses.

   noqiflush
       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, 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).

   typeahead
       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

       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,

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

PORTABILITY

       These functions are described in the XSI Curses standard, Issue 4.

       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 mode.

       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

       Note that  echo,  noecho,  halfdelay,  intrflush,  meta,  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

       ncurses(3NCURSES),       getch(3NCURSES),        initscr(3NCURSES),        util(3NCURSES),
       define_key(3NCURSES), termios(3)

                                                                                 inopts(3NCURSES)