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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | EXTENSIONS | PORTABILITY | SEE ALSO | COLOPHON |
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curs_kernel(3X) Library calls curs_kernel(3X)
def_prog_mode, def_shell_mode, reset_prog_mode, reset_shell_mode,
resetty, savetty, getsyx, setsyx, curs_set, mvcur, napms,
ripoffline - low-level curses routines
#include <curses.h>
int def_prog_mode(void);
int def_shell_mode(void);
int reset_prog_mode(void);
int reset_shell_mode(void);
int resetty(void);
int savetty(void);
void getsyx(int y, int x);
void setsyx(int y, int x);
int curs_set(int visibility);
int mvcur(int oldrow, int oldcol, int newrow, int newcol);
int napms(int ms);
int ripoffline(int line, int (*init)(WINDOW *, int));
The following routines give low-level access to various curses
capabilities. These routines typically are used inside library
routines.
def_prog_mode, def_shell_mode
The def_prog_mode and def_shell_mode routines save the current
terminal modes as the “program” (in curses) or “shell” (not in
curses) state for use by the reset_prog_mode and reset_shell_mode
routines. This is done automatically by initscr. There is one
such save area for each screen context allocated by newterm.
reset_prog_mode, reset_shell_mode
The reset_prog_mode and reset_shell_mode routines restore the
terminal to “program” (in curses) or “shell” (out of curses)
state. These are done automatically by endwin(3X) and, after an
endwin, by doupdate, so they normally are not called.
resetty, savetty
The resetty and savetty routines save and restore the state of the
terminal modes. savetty saves the current state in a buffer and
resetty restores the state to what it was at the last call to
savetty.
getsyx
getsyx stores the coordinates of virtual screen (newscr) cursor in
y and x. If newscr's leaveok(3X) output option is TRUE, getsyx
stores -1 in both y and x. If lines have been removed from the
top of the screen using ripoffline, y includes these lines;
therefore, y and x populated by getsyx should be used only as
arguments for setsyx.
Few applications use this feature; most call getyx(3X) instead.
setsyx
setsyx sets the virtual screen (newscr) cursor location to (y, x).
setsyx(-1, -1) is equivalent to leaveok(newscr, TRUE).
getsyx and setsyx are designed to be used by a function that
manipulates curses windows but seeks to avoid changing the cursor
position. Such a function would first call getsyx, modify its
windows' content, call wnoutrefresh(3X) on them, call setsyx, then
call doupdate(3X).
Few applications use this feature; most call wmove(3X) instead.
curs_set
curs_set adjusts the cursor visibility to “invisible”, “visible”,
“very visible”, as its argument is 0, 1, or 2, respectively. It
returns the previous visibility if the requested one is supported,
and ERR otherwise.
mvcur
mvcur provides low-level cursor motion. It takes effect
immediately, rather than at the next refresh. Unlike the other
low-level output functions, which either write to the standard
output stream or are passed a function pointer to perform output,
mvcur uses a file descriptor derived from the output stream
parameter of newterm(3X).
One application of mvcur accompanies the temporary use of another
program to write to the terminal screen. For example, first call
refresh(3X) to ensure that the screen and the library's model of
it are up to date; then call reset_shell_mode; write to the screen
with the external application; call reset_prog_mode; and finally
call mvcur(..., ..., -1, -1) to move the terminal cursor to where
curses thinks it is, since the library has no knowledge of how the
external application moved it.
napms
napms sleeps for ms milliseconds. If ms exceeds 30,000 (thirty
seconds), ncurses caps it at that value.
ripoffline
ripoffline provides access to the same facility that slk_init(3X)
uses to reduce the size of the screen. The application must call
ripoffline before initscr(3X) or newterm(3X) so that the latter
functions prepare a stdscr of the correct size.
• If line is positive, ripoffline removes a line from the top of
what will become stdscr.
• If line is negative, ripoffline removes a line from the bottom
of what will become stdscr.
When initscr initializes curses, it calls the init function
supplied to ripoffline by the application with two arguments:
• a pointer to the one-line WINDOW that it allocates, and
• an integer with the number of columns in the window.
Inside this init function, the values of the integer variables
LINES and COLS (see curs_variables(3X)) are not guaranteed to be
reliable; it must not call wrefresh(3X) or doupdate(3X). A
wnoutrefresh(3X) call is permissible.
ripoffline can be called up to five times before initscr or
newterm.
Except for curs_set, these functions return OK on success and ERR
on failure.
curs_set returns the previous cursor visibility, and returns ERR
if the terminal type does not support the requested visibility.
napms always succeeds.
mvcur fails if the position (newrow, newcol) is outside the screen
boundaries.
In ncurses,
• def_prog_mode, def_shell_mode, reset_prog_mode, and
reset_shell_mode return ERR if the terminal was not
initialized, or if the operating system's function for
obtaining terminal settings fails.
• ripoffline returns ERR if the accumulated quantity of ripped-
off lines would exceed the maximum (5).
getsyx is a macro; use of the & operator before its arguments is
unnecessary.
The endwin function of both ncurses and SVr4 curses calls curs_set
if the latter has previously been called to set the cursor
visibility to a value other than normal; that is, either invisible
or very visible. There is no way for ncurses to determine the
initial cursor visibility to restore it.
ncurses imposes a limit of 30 seconds on a delay requested of
napms.
While the init function called by ripoffline is specified to
return an int, ncurses pays no attention to its return value.
If ripoffline cannot allocate memory for the required WINDOW
structure backing the ripped-off line, it stores a null pointer to
the WINDOW pointer argument supplied by the init function the
application specifies. The application must check this argument
for validity after calling initscr and prior to performing curses
operations on that window.
In ncurses, mvcur accepts -1 for either or both old coordinates.
This value tells ncurses that the old location is unknown, and
that it must use only absolute motion, as with the cursor_address
(cup) capability, rather than the least costly combination of
absolute and relative motion.
Applications employing ncurses extensions should condition their
use on the visibility of the NCURSES_VERSION preprocessor macro.
The virtual screen functions setsyx and getsyx are not described
in X/Open Curses Issue 4. SVr4 documents each of them as
returning an int. This is misleading, as they are macros with no
documented semantics for returning values.
All other functions are as described in X/Open Curses. It
specifies no error conditions for them, except as described for
curs_set in section “RETURN VALUE” above.
The System V Interface Definition, Version 4 (1995), specified all
of these functions except curs_set as returning OK.
Older SVr4 man pages warn that the return value of curs_set “is
currently incorrect”. This implementation gets it right, but
counting on its correctness anywhere else may be unwise.
X/Open Curses specifies ripoffline as returning OK with no
possibility of failure (“[c]alls to ripoffline above this limit
[five lines] have no effect but report success”).
X/Open Curses notes:
After use of mvcur(), the model Curses maintains of the
state of the terminal might not match the actual state of
the terminal. An application should touch and refresh the
window before resuming conventional use of Curses.
Both ncurses and SVr4 curses implement mvcur using the SCREEN
object allocated in either initscr(3X) or newterm(3X). X/Open
Curses states that the old location must be given for mvcur to
accommodate terminals that lack absolute cursor positioning.
If interrupted by a signal, ncurses restarts napms. That, and the
limitation to 30 seconds, differ from other implementations.
curses(3X), curs_initscr(3X), curs_outopts(3X), curs_refresh(3X),
curs_scr_dump(3X), curs_slk(3X), curs_variables(3X)
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... 2025-08-16 curs_kernel(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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