ncurses 6.1 - patch 20190216

[ncurses.git] / man / curs_getch.3x

diff --git a/man/curs_getch.3x b/man/curs_getch.3x
index 642205a8c5f72082a9838c7a437371b265c065e8..53716beeff916deed4482bd309abb049a05e56c9 100644 (file)
--- a/man/curs_getch.3x
+++ b/man/curs_getch.3x
@@ -1,6 +1,6 @@
 '\" t
 .\"***************************************************************************
-.\" Copyright (c) 1998-2015,2016 Free Software Foundation, Inc.              *
+.\" Copyright (c) 1998-2017,2018 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 +27,13 @@
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"
-.\" $Id: curs_getch.3x,v 1.45 2016/05/15 01:05:18 tom Exp $
+.\" $Id: curs_getch.3x,v 1.53 2018/07/28 22:15:59 tom Exp $
 .TH curs_getch 3X ""
 .na
 .hy 0
 .de bP
-.IP \(bu 4
+.ie n  .IP \(bu 4
+.el    .IP \(bu 2
 ..
 .SH NAME
 \fBgetch\fR,
@@ -102,7 +103,8 @@ 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.
 .bP
-Other (user-defined) function keys which may be defined using \fBdefine_key\fP(3X)
+Other (user-defined) function keys which may be defined
+using \fBdefine_key\fP(3X)
 have no names, but also are expected to have values outside the range of
 8-bit characters.
 .PP
@@ -118,6 +120,14 @@ time, the character is passed through;
 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.
+.PP
+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
 .PP
 The \fBungetch\fR routine places \fIch\fR back onto the input queue to be
@@ -282,18 +292,20 @@ string (see \fBkey_defined\fP(3X)).
 .PP
 .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
 completion.
 .RS 3
 .TP 5
 \fBungetch\fP
-returns ERR
+returns \fBERR\fP
 if there is no more room in the FIFO.
 .TP
 \fBwgetch\fP
-returns ERR
+returns \fBERR\fP
 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
+\fBEINTR\fR).
 .RE
 .PP
 Functions with a "mv" prefix first perform a cursor movement using
@@ -305,7 +317,9 @@ discouraged, as it will cause a delay of up to one second while the
 keypad code looks for a following function-key sequence.
 .PP
 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.
+keys, e.g.,
+\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.
@@ -371,15 +385,13 @@ input timeout or non-blocking mode has been set.
 terminfo capabilities, but no higher-level functions use the feature.
 The implementation in ncurses is an extension.
 .PP
-\fBKEY_RESIZE\fP is an extension first implemented for ncurses. 
+\fBKEY_RESIZE\fP is an extension first implemented for ncurses.
 NetBSD curses later added this extension.
 .PP
 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
 \fBEINTR\fR.
-Under the \fBncurses\fR implementation, handled signals never
-interrupt \fBgetch\fR.
 .PP
 The \fBhas_key\fR function is unique to \fBncurses\fR.
 We recommend that
@@ -391,6 +403,7 @@ any code using it be conditionalized on the \fBNCURSES_VERSION\fR feature macro.
 \fBcurs_mouse\fR(3X),
 \fBcurs_move\fR(3X),
 \fBcurs_refresh\fR(3X),
+\fBcurs_variables\fR(3X),
 \fBresizeterm\fR(3X).
 .PP
 Comparable functions in the wide-character (ncursesw) library are