Provided by: ncurses-doc_6.3-2ubuntu0.1_all bug

NAME

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

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/nocbreak
       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.

   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 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.

   qiflush/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.

       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

       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

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

                                                                                 inopts(3NCURSES)