Diffstat (limited to 'man/curs_getch.3x')
1 files changed, 112 insertions, 41 deletions
diff --git a/man/curs_getch.3x b/man/curs_getch.3x
index a8b2ffea1868..fbebd45d0b15 100644
@@ -1,6 +1,6 @@
-.\" Copyright (c) 1998-2011,2012 Free Software Foundation, Inc. *
+.\" Copyright (c) 1998-2018,2019 Free Software Foundation, Inc. *
.\" Permission is hereby granted, free of charge, to any person obtaining a *
.\" copy of this software and associated documentation files (the *
@@ -27,12 +27,17 @@
.\" authorization. *
-.\" $Id: curs_getch.3x,v 1.37 2012/07/07 20:04:56 tom Exp $
+.\" $Id: curs_getch.3x,v 1.54 2019/11/30 21:06:30 tom Exp $
.TH curs_getch 3X ""
+.ie \n(.g .ds `` \(lq
+.el .ds `` ``
+.ie \n(.g .ds '' \(rq
+.el .ds '' ''
-.IP \(bu 4
+.ie n .IP \(bu 4
+.el .IP \(bu 2
@@ -48,17 +53,18 @@
-\fBint wgetch(WINDOW *win);\fR
+\fBint wgetch(WINDOW *\fP\fIwin);\fR
-\fBint mvgetch(int y, int x);\fR
+\fBint mvgetch(int \fP\fIy\fP\fB, int \fP\fIx\fP\fB);\fR
-\fBint mvwgetch(WINDOW *win, int y, int x);\fR
+\fBint mvwgetch(WINDOW *\fP\fIwin\fP\fB, int \fP\fIy\fP\fB, int \fP\fIx\fP\fB);\fR
-\fBint ungetch(int ch);\fR
+\fBint ungetch(int \fP\fIch\fP\fB);\fR
-\fBint has_key(int ch);\fR
+\fBint has_key(int \fP\fIch\fP\fB);\fR
+.SS Reading characters
The \fBgetch\fR, \fBwgetch\fR, \fBmvgetch\fR and \fBmvwgetch\fR, routines read
a character from the window.
In no-delay mode, if no input is waiting, the value \fBERR\fR is returned.
@@ -71,25 +77,42 @@ In half-delay mode,
the program waits until a character is typed or the
specified timeout has been reached.
-Unless \fBnoecho\fR has been set,
+If \fBecho\fR is enabled, and the window is not a pad,
then the character will also be echoed into the
designated window according to the following rules:
-if the character is the current erase character, left arrow, or backspace,
+If the character is the current erase character, left arrow, or backspace,
the cursor is moved one space to the left and that screen position is erased
as if \fBdelch\fR had been called.
If the character value is any other \fBKEY_\fR define, the user is alerted
with a \fBbeep\fR call.
+If the character is a carriage-return,
+and if \fBnl\fP is enabled,
+it is translated to a line-feed after echoing.
Otherwise the character is simply output to the screen.
If the window is not a pad, and it has been moved or modified since the last
call to \fBwrefresh\fR, \fBwrefresh\fR will be called before another character
+.SS Keypad mode
If \fBkeypad\fR is \fBTRUE\fR, and a function key is pressed, the token for
-that function key is returned instead of the raw characters.
-keys are defined in \fB<curses.h>\fR as macros with values outside the range
-of 8-bit characters whose names begin with \fBKEY_\fR. Thus, a variable
+that function key is returned instead of the raw characters:
+The predefined function
+keys are listed in \fB<curses.h>\fR as macros with values outside the range
+of 8-bit characters.
+Their names begin with \fBKEY_\fR.
+Other (user-defined) function keys which may be defined
+have no names, but also are expected to have values outside the range of
+Thus, a variable
intended to hold the return value of a function key must be of short size or
@@ -102,21 +125,37 @@ otherwise, the function key value is returned.
For this reason, many terminals experience a delay between the time
a user presses the escape key and the escape is returned to the program.
+In \fBncurses\fP, the timer normally expires after
+the value in \fBESCDELAY\fP (see \fBcurs_variables\fP(3X)).
+If \fBnotimeout\fP is \fBTRUE\fP, the timer does not expire;
+it is an infinite (or very large) value.
+Because function keys usually begin with an escape character,
+the terminal may appear to hang in notimeout mode after pressing the escape key
+until another key is pressed.
+.SS Ungetting characters
The \fBungetch\fR routine places \fIch\fR back onto the input queue to be
returned by the next call to \fBwgetch\fR.
There is just one input queue for all windows.
-.SS Function Keys
-The following function keys, defined in \fB<curses.h>\fR, might be returned by
-\fBgetch\fR if \fBkeypad\fR has been enabled.
-Note that not all of these are
-necessarily supported on any particular terminal.
+.SS Predefined key-codes
+The following special keys are defined in \fB<curses.h>\fR.
+Except for the special case \fBKEY_RESIZE\fP,
+it is necessary to enable \fBkeypad\fR for \fBgetch\fP to return these codes.
+Not all of these are necessarily supported on any particular terminal.
+The naming convention may seem obscure, with some apparent
+misspellings (such as \*(``RSUME\*('' for \*(``resume\*('').
+The names correspond to the long terminfo capability names for the keys,
+and were defined long ago, in the 1980s.
center tab(/) ;
l l .
KEY_DOWN/The four arrow keys ...
@@ -216,7 +255,7 @@ KEY_UNDO/Undo key
Keypad is arranged like this:
center allbox tab(/) ;
c c c .
@@ -225,31 +264,55 @@ c c c .
-The \fBhas_key\fR routine takes a key value from the above list, and
-returns TRUE or FALSE according to whether
+A few of these predefined values do \fInot\fP correspond to a real key:
+is returned when the \fBSIGWINCH\fP signal has been detected
+(see \fBinitscr\fP(3X) and \fBresizeterm\fR(3X)).
+This code is returned whether or not \fBkeypad\fP has been enabled.
+is returned for mouse-events (see \fBcurs_mouse\fR(3X)).
+This code relies upon whether or not \fBkeypad\fP(3X) has been enabled,
+because (e.g., with \fIxterm\fP mouse prototocol) ncurses must
+read escape sequences,
+just like a function key.
+.SS Testing key-codes
+The \fBhas_key\fR routine takes a key-code value from the above list, and
+returns \fBTRUE\fP or \fBFALSE\fP according to whether
the current terminal type recognizes a key with that value.
-Note that a few values do not correspond to a real key,
-e.g., \fBKEY_RESIZE\fP and \fBKEY_MOUSE\fP.
-See \fBresizeterm\fR(3X) for more details about \fBKEY_RESIZE\fP, and
-\fBcurs_mouse\fR(3X) for a discussion of \fBKEY_MOUSE\fP.
+The library also supports these extensions:
+defines a key-code for a given string (see \fBdefine_key\fP(3X)).
+checks if there is a key-code defined for a given
+string (see \fBkey_defined\fP(3X)).
.SH RETURN VALUE
All routines return the integer \fBERR\fR upon failure and an integer value
-other than \fBERR\fR (\fBOK\fR in the case of ungetch()) upon successful
+other than \fBERR\fR (\fBOK\fR in the case of \fBungetch\fP) upon successful
if there is no more room in the FIFO.
if the window pointer is null, or
-if its timeout expires without having any data.
+if its timeout expires without having any data, or
+if the execution was interrupted by a signal (\fBerrno\fR will be set to
-Functions with a "mv" prefix first perform a cursor movement using
+Functions with a \*(``mv\*('' prefix first perform a cursor movement using
\fBwmove\fP, and return an error if the position is outside the window,
or if the window pointer is null.
@@ -257,8 +320,10 @@ Use of the escape key by a programmer for a single character function is
discouraged, as it will cause a delay of up to one second while the
keypad code looks for a following function-key sequence.
-Note that some keys may be the same as commonly used control
-keys, e.g., \fBKEY_ENTER\fP versus control/M, \fBKEY_BACKSPACE\fP versus control/H.
+Some keys may be the same as commonly used control
+\fBKEY_ENTER\fP versus control/M,
+\fBKEY_BACKSPACE\fP versus control/H.
Some curses implementations may differ according to whether they
treat these control keys specially (and ignore the terminfo), or
use the terminfo definitions.
@@ -276,10 +341,10 @@ the \fIEnter\fP key on the regular keyboard is already handled by
the standard ASCII characters for carriage-return and line-feed,
depending on whether \fBnl\fP or \fBnonl\fP was called,
-pressing "Enter" on the regular keyboard may return either a carriage-return
-or line-feed, and finally
+pressing \*(``Enter\*('' on the regular keyboard
+may return either a carriage-return or line-feed, and finally
-"Enter or send" is the standard description for this key.
+\*(``Enter or send\*('' is the standard description for this key.
When using \fBgetch\fR, \fBwgetch\fR, \fBmvgetch\fR, or
\fBmvwgetch\fR, nocbreak mode (\fBnocbreak\fR) and echo mode
@@ -320,12 +385,17 @@ implementation of handled signal receipt interrupts a \fBread\fR(2) call in
progress or not, and also (in some implementations) depending on whether an
input timeout or non-blocking mode has been set.
+\fBKEY_MOUSE\fP is mentioned in XSI Curses, along with a few related
+terminfo capabilities, but no higher-level functions use the feature.
+The implementation in ncurses is an extension.
+\fBKEY_RESIZE\fP is an extension first implemented for ncurses.
+NetBSD curses later added this extension.
Programmers concerned about portability should be prepared for either of two
cases: (a) signal receipt does not interrupt \fBgetch\fR; (b) signal receipt
-interrupts \fBgetch\fR and causes it to return ERR with \fBerrno\fR set to
+interrupts \fBgetch\fR and causes it to return \fBERR\fP with \fBerrno\fR set to
-Under the \fBncurses\fR implementation, handled signals never
The \fBhas_key\fR function is unique to \fBncurses\fR.
We recommend that
@@ -337,6 +407,7 @@ any code using it be conditionalized on the \fBNCURSES_VERSION\fR feature macro.
Comparable functions in the wide-character (ncursesw) library are