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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | EXTENSIONS | PORTABILITY | HISTORY | SEE ALSO | COLOPHON |
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curs_getch(3X) Library calls curs_getch(3X)
getch, wgetch, mvgetch, mvwgetch, ungetch, has_key - get (or push
back) characters from curses terminal keyboard buffer
#include <curses.h>
int getch(void);
int wgetch(WINDOW * win);
int mvgetch(int y, int x);
int mvwgetch(WINDOW * win, int y, int x);
int ungetch(int c);
/* extension */
int has_key(int c);
Reading Characters
wgetch gathers a key event from the terminal keyboard associated
with a curses window win. ncurses(3X) describes the variants of
this function.
When input is pending, wgetch returns an integer identifying the
key event; for alphanumeric and punctuation keys, the space bar,
and (usually) the Backspace, Tab, Return, and Escape keys, this
value corresponds to the character encoding used by the terminal.
Use of the control key as a modifier, by holding it down while
pressing and releasing another key, often results in a distinct
code. The behavior of other keys depends on whether win is in
keypad mode; see subsection “Keypad Mode” below.
If no input is pending, then if the no-delay flag is set in the
window (see nodelay(3X)), the function returns ERR; otherwise,
curses waits until the terminal has input. If cbreak(3X) or
raw(3X) has been called, this happens after curses reads one key
event. If nocbreak(3X) or noraw(3X) has been called, it occurs
when curses reads a newline. (Because the terminal's canonical or
“cooked” mode is line-buffered, multiple wgetch calls may then be
necessary to empty the input queue.) If halfdelay(3X) has been
called, curses waits until input is available or the specified
delay elapses.
If echo(3X) has been called, and the window is not a pad, curses
writes the returned character c to the window (at the cursor
position) per the following rules.
• If c matches the terminal's erase character (see
erasechar(3X)), and the cursor is not at the window's leftmost
column, the cursor moves leftward one position and the new
position is erased as if wmove(3X) and then wdelch(3X) were
called. When the window's keypad mode is enabled (see below),
KEY_LEFT and KEY_BACKSPACE are handled the same way.
• curses writes any other c to the window, as with
wechochar(3X).
• If the window win has been moved or modified since the last
call to wrefresh(3X), curses calls wrefresh on it.
If c is a carriage return and nl(3X) has been called, wgetch
returns the character code for line feed instead.
Keypad Mode
Call keypad(3X) on a window to configure keypad mode when reading
input from it. In keypad mode, curses treats key strokes not from
the alphabetic section of the keyboard (those corresponding to the
ECMA-6 character set — see ascii(7) — optionally modified by
either the control or shift keys) as function keys. (In curses,
the term “function key” includes but is not limited to keycaps
engraved with “F1”, “PF1”, and so on.) If a window is in keypad
mode, wgetch translates these key strokes to a numeric code
corresponding to the KEY_ symbols listed in subsection “Key Codes”
below. If the window is not in keypad mode, the input queue
populates with the characters of the function key's escape
sequence, which the application must collect individually with
multiple wgetch calls.
• The curses.h header file declares many function keys whose
names begin with KEY_; these object-like macros have integer
values outside the range of eight-bit character codes.
• In ncurses, user-defined function keys are configured with
define_key(3X); they have no names, but are also expected to
have integer values outside the range of eight-bit character
codes.
A variable intended to hold a function key code must thus be of
type short or larger.
Most terminals one encounters follow the ECMA-48 standard insofar
as their function keys produce character sequences prefixed with
the escape character ESC. This fact implies that curses cannot
distinguish a user's press of the escape key (assuming it sends
ESC) from the beginning of a function key's character sequence
without waiting to see if, and how soon, further input arrives.
• If the escape sequence matches a string capability defining a
function key for the terminal type (such as key_home (khome)
or key_up (kuu1)), wgetch returns the function key code
corresponding to the unique sequence defined by the terminal.
• If the escape sequence matches no function keys defined for
the terminal type, call wgetch repeatedly to obtain the codes
of the individual characters of the sequence, in the order
they occurred in the input.
• If wgetch cannot decide the validity of the input as a
function key because it has not read enough characters to
disambiguate it, the function waits until it has this
information or the escape delay elapses. Configure the escape
delay with the global variable ESCDELAY, an extension (see
section “EXTENSIONS” below), or the environment variable of
the same name (see section “ENVIRONMENT” of ncurses(3X)), also
an extension.
Consequently, a user of a curses application that employs keypad
mode may experience a pause or “hang” after pressing the escape
key while curses collects sufficient characters to disambiguate
the input. If the window is in “no time-out” mode, the escape
delay is effectively infinite; see notimeout(3X). In the event of
such a pause, further typing “awakens” curses.
Ungetting Characters
ungetch places c into the input queue to be returned by the next
call to wgetch. A single input queue serves all windows
associated with the screen.
Key Codes
The header file curses.h defines the following function key codes.
• Except for the special case of KEY_RESIZE, a window's keypad
mode must be enabled for wgetch to read these codes from it.
• 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 terminfo capability names for the keys, and
were standardized before the IBM PC/AT keyboard layout
achieved a dominant position in industry.
Symbol Key name
────────────────────────────────────────────────────────────
KEY_BREAK Break key
KEY_DOWN
KEY_UP Arrow keys
KEY_LEFT
KEY_RIGHT
KEY_HOME Home key (upward+left arrow)
KEY_BACKSPACE Backspace
KEY_F0 Function keys; space for 64 keys is
reserved
KEY_F(n) Function key n where 0 ≤ n ≤ 63
KEY_DL Delete line
KEY_IL Insert line
KEY_DC Delete character
KEY_IC Insert character/Enter insert mode
KEY_EIC Exit insert character mode
KEY_CLEAR Clear screen
KEY_EOS Clear to end of screen
KEY_EOL Clear to end of line
KEY_SF Scroll one line forward
KEY_SR Scroll one line backward (reverse)
KEY_NPAGE Next page/Page up
KEY_PPAGE Previous page/Page down
KEY_STAB Set tab
KEY_CTAB Clear tab
KEY_CATAB Clear all tabs
KEY_ENTER Enter/Send
KEY_SRESET Soft (partial) reset
KEY_RESET (Hard) reset
KEY_PRINT Print/Copy
KEY_LL Home down/Bottom (lower left)
KEY_A1 Upper left of keypad
KEY_A3 Upper right of keypad
KEY_B2 Center of keypad
KEY_C1 Lower left of keypad
KEY_C3 Lower right of keypad
KEY_BTAB Back tab key
KEY_BEG Beg(inning) key
KEY_CANCEL Cancel key
KEY_CLOSE Close key
KEY_COMMAND Cmd (command) key
KEY_COPY Copy key
KEY_CREATE Create key
KEY_END End key
KEY_EXIT Exit key
KEY_FIND Find key
KEY_HELP Help key
KEY_MARK Mark key
KEY_MESSAGE Message key
KEY_MOUSE Mouse event occurred
KEY_MOVE Move key
KEY_NEXT Next object key
KEY_OPEN Open key
KEY_OPTIONS Options key
KEY_PREVIOUS Previous object key
KEY_REDO Redo key
KEY_REFERENCE Ref(erence) key
KEY_REFRESH Refresh key
KEY_REPLACE Replace key
KEY_RESIZE Screen resized
KEY_RESTART Restart key
KEY_RESUME Resume key
KEY_SAVE Save key
KEY_SELECT Select key
KEY_SUSPEND Suspend key
KEY_UNDO Undo key
────────────────────────────────────────────────────────────
KEY_SBEG Shifted beginning key
KEY_SCANCEL Shifted cancel key
KEY_SCOMMAND Shifted command key
KEY_SCOPY Shifted copy key
KEY_SCREATE Shifted create key
KEY_SDC Shifted delete character key
KEY_SDL Shifted delete line key
KEY_SEND Shifted end key
KEY_SEOL Shifted clear line key
KEY_SEXIT Shifted exit key
KEY_SFIND Shifted find key
KEY_SHELP Shifted help key
KEY_SHOME Shifted home key
KEY_SIC Shifted insert key
KEY_SLEFT Shifted left arrow key
KEY_SMESSAGE Shifted message key
KEY_SMOVE Shifted move key
KEY_SNEXT Shifted next object key
KEY_SOPTIONS Shifted options key
KEY_SPREVIOUS Shifted previous object key
KEY_SPRINT Shifted print key
KEY_SREDO Shifted redo key
KEY_SREPLACE Shifted replace key
KEY_SRIGHT Shifted right arrow key
KEY_SRSUME Shifted resume key
KEY_SSAVE Shifted save key
KEY_SSUSPEND Shifted suspend key
KEY_SUNDO Shifted undo key
Many keyboards feature a nine-key directional pad.
┌──────┬──────┬───────┐
│ A1 │ up │ A3 │
├──────┼──────┼───────┤
│ left │ B2 │ right │
├──────┼──────┼───────┤
│ C1 │ down │ C3 │
└──────┴──────┴───────┘
Two of the symbols in the list above do not correspond to a
physical key.
• wgetch returns KEY_RESIZE, even if the window's keypad mode is
disabled, if ncurses has handled a SIGWINCH signal since
wgetch was called; see initscr(3X) and resizeterm(3X).
• wgetch returns KEY_MOUSE to indicate that a mouse event is
pending collection; see curs_mouse(3X). Receipt of this code
requires a window's keypad mode to be enabled, because to
interpret mouse input (as with xterm(1)'s mouse protocol),
ncurses must read an escape sequence, as with a function key.
Testing Key Codes
In ncurses, has_key returns a Boolean value indicating whether the
terminal type recognizes its parameter as a key code value. See
also define_key(3X) and key_defined(3X).
wgetch returns a key code identifying the key event as described
above, which may include KEY_RESIZE or KEY_MOUSE indicating non-
key events, or ERR on failure. wgetch fails if its timeout
expires without any data arriving, which cannot happen if
nodelay(3X) is in effect on the window.
In ncurses, wgetch also fails if
• the curses screen has not been initialized,
• (for functions taking a WINDOW pointer argument) win is a null
pointer, or
• execution was interrupted by a signal, in which case the
library sets errno to EINTR.
Functions prefixed with “mv” first perform cursor movement and
fail if the position (y, x) is outside the window boundaries.
ungetch returns OK on success and ERR on failure. In ncurses,
ungetch fails if
• the curses screen has not been initialized, or
• there is no more room in the input queue.
has_key returns TRUE or FALSE.
getch, mvgetch, and mvwgetch may be implemented as macros.
curses discourages assignment of the ESC key to a discrete
function by the programmer because the library requires a delay
while it awaits the potential remainder of a terminal escape
sequence.
Some key strokes are indistinguishable from control characters;
for example, KEY_ENTER may be the same as ^M, and KEY_BACKSPACE
may be the same as ^H or ^?. Consult the terminfo entry for the
terminal type to determine whether this is the case; see
infocmp(1). Some curses implementations, including ncurses, honor
the terminfo key definitions; others treat such control characters
specially.
curses distinguishes the Enter keys in the alphabetic and numeric
keypad sections of a keyboard because (most) terminals do.
KEY_ENTER refers to the key on the numeric keypad and, like other
function keys, is reliably recognized only if the window's keypad
mode is enabled.
• The terminfo key_enter (kent) capability describes the
character (sequence) sent by the Enter key of a terminal's
numeric (or similar) keypad.
• “Enter or send” is X/Open Curses's description of this key.
curses treats the Enter or Return key in the alphabetic section of
the keyboard differently.
• It usually produces a control code for carriage return (^M) or
line feed (^J).
• Depending on the terminal mode (raw, cbreak, or canonical),
and whether nl(3X) or nonl(3X) has been called, wgetch may
return either a carriage return or line feed upon an Enter or
Return key stroke.
Use of wgetch with echo(3X) and neither cbreak(3X) nor raw(3X) is
not well-defined.
Historically, the list of key code macros above was influenced by
the keyboard of the AT&T 7300 (also known variously as the “3B1”,
“Safari 4”, and “UNIX PC”), a 1985 machine rich in function keys.
Today's computer keyboards are based on that of the IBM PC/AT and
tend to have fewer. A curses application can expect such a
keyboard to transmit key codes KEY_UP, KEY_DOWN, KEY_LEFT,
KEY_RIGHT, KEY_HOME, KEY_END, KEY_PPAGE (Page Up), KEY_NPAGE (Page
Down), KEY_IC (Insert), KEY_DC (Delete), KEY_A1, KEY_A3, KEY_B2,
KEY_C1, KEY_C3, and KEY_F(n) for 1 ≤ n ≤ 12.
In ncurses, when a window's “no time-out” mode is not set, the
ESCDELAY variable configures the duration of the timer used to
disambiguate a function key character sequence from a series of
key strokes beginning with ESC typed by the user; see
curs_variables(3X).
has_key is an ncurses extension, and is not found in SVr4 curses,
4.4BSD curses, or any other previous curses implementation.
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 describes these functions. It specifies no error
conditions for them.
SVr4 describes a successful return value only as “an integer value
other than ERR”.
wgetch reads only single-byte characters.
The echo behavior of these functions on input of KEY_ or backspace
characters is not documented in SVr4 curses.
The behavior of wgetch in the presence of signal handlers is not
documented in SVr4 curses and is unspecified by X/Open Curses. In
historical curses implementations, it varied depending on whether
the operating system's dispatch of a signal to a handler
interrupted a read(2) call in progress, and also (in some
implementations) whether an input timeout or non-blocking mode had
been set. A portable curses application prepares for two cases:
(a) signal receipt does not interrupt wgetch; and (b) signal
receipt interrupts wgetch and causes it to return ERR with errno
set to EINTR.
KEY_MOUSE is mentioned in X/Open Curses, along with a few related
terminfo capabilities, but no higher-level functions use the
feature. The implementation in ncurses is an extension.
KEY_RESIZE and has_key are extensions first implemented for
ncurses. By 2022, PDCurses and NetBSD curses had added them along
with KEY_MOUSE.
4BSD (1980) introduced wgetch and its variants.
SVr3 (1987) added ungetch.
ncurses 1.9.9g (1996) furnished the has_key extension.
ECMA-6 “7-bit coded Character Set” <https://ecma-international
.org/publications-and-standards/standards/ecma-6/>
ECMA-48 “Control Functions for Coded Character Sets” <https://
ecma-international.org/publications-and-standards/standards/
ecma-48/>
curs_get_wch(3X) describes comparable functions of the ncurses
library in its wide-character configuration (ncursesw).
curses(3X), curs_addch(3X), curs_inopts(3X), curs_mouse(3X),
curs_move(3X), curs_outopts(3X), curs_refresh(3X),
curs_variables(3X), resizeterm(3X), ascii(7)
This page is part of the ncurses (new curses) project.
Information about the project can be found at
⟨https://invisible-island.net/ncurses/ncurses.html⟩. If you have a
bug report for this manual page, send it to bug-ncurses@gnu.org.
This page was obtained from the tarball ncurses-6.6.tar.gz fetched
from ⟨https://ftp.gnu.org/gnu/ncurses/⟩ on 2026-01-16. If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for the
page, or you have corrections or improvements to the information
in this COLOPHON (which is not part of the original manual page),
send a mail to man-pages@man7.org
ncurses @NCURSES_MAJOR@.@NCU... 2025-11-11 curs_getch(3X)
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HTML rendering created 2026-01-16 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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