# curs_inopts 3x 2023-10-07 ncurses 6.4 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

           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 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 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 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.

## EXTENSIONS

           This implementation provides four functions which 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 curses library was not initialized.

           These  routines  are  specific  to ncurses.  They were not supported on
           Version 7, BSD or System V implementations.  It is recommended that any
           code   depending   on   ncurses   extensions   be   conditioned   using
           NCURSES_VERSION.

## PORTABILITY

           Except as noted in the  section  on  extensions,  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

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

    ncurses 6.4                       2023-10-07                   curs_inopts(3x)