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curs_inopts(3X)						       curs_inopts(3X)

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

       #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);

       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 charac‐
       ters 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 explic‐
       itly.  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.]

       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 curs_getch(3X)
       for a discussion	 of  how  these	 routines  interact  with  cbreak  and

       The  halfdelay routine is used for half-delay mode, which is similar to
       cbreak mode in that characters typed by the user are immediately avail‐
       able to the program.  However, after blocking for tenths tenths of sec‐
       onds, 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

       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  en‐
       abled (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 func‐
       tion keys specially and the program has to  interpret  the  escape  se‐
       quences	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  in‐
       put  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  equiva‐
       lent, 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 termi‐
       nal 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	 imme‐
       diately	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 re‐
       fresh or doupdate is called again.  This allows faster response to com‐
       mands  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.

       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 descrip‐

       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 initial‐
       ized.  Also,

		   returns  an	error  if  its	parameter is outside the range

       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 pro‐
       gram remains in cooked mode.

       When keypad is first enabled, ncurses loads the key-definitions for the
       current terminal description.  If the terminal description includes ex‐
       tended 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 previ‐
       ous  loads of terminal descriptions) may differ from one execution of a
       program to the next.  The generated keycodes are recognized by the key‐
       name  function (which will then return a name beginning with "k" denot‐
       ing the terminfo capability name rather than "K", used for curses  key-
       names).	On the other hand, an application can use define_key to estab‐
       lish 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 ca‐
       pability's value is the same as a previously-loaded key definition, the
       later definition is the one used.

       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

       curses(3X),  curs_getch(3X),   curs_initscr(3X),	  curs_util(3X),   de‐
       fine_key(3X), termio(7)


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