Ubuntu Manpage: cbreak, nocbreak, echo, noecho, halfdelay, intrflush, keypad, meta, nodelay, notimeout, raw, noraw,

Provided by: ncurses-doc_5.9+20140118-1ubuntu1_all

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

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.]

The echo and noecho routines control whether characters typed by the user are echoed by getch 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.]

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), when 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
(bf is FALSE), the option prevents the flush. The default for the option is inherited from the tty
driver settings. The window argument is ignored.

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 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 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 termio(7)]. 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 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 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 curses.

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 termio(7)]. 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 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