# curs_inopts 3x 2024-04-13 ncurses 6.5 Library calls

    curs_inopts(3x)                  Library calls                 curs_inopts(3x)

## 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(3x)