This is an extension to the curses library. It provides callers with
a hook into the ncurses data to resize windows, primarily for use by
programs running in an X Window terminal (e.g., xterm).
The function resizeterm resizes the standard and current windows to
the specified dimensions, and adjusts other bookkeeping data used by
the ncurses library that record the window dimensions such as the
LINES and COLS variables.
Most of the work is done by the inner function resize_term. The
outer function resizeterm adds bookkeeping for the SIGWINCH handler,
as well as repainting the soft-key area (see slk_touch(3X)).
When resizing the windows, resize_term blank-fills the areas that are
extended. The calling application should fill in these areas with
The resize_term function attempts to resize all windows. However,
due to the calling convention of pads, it is not possible to resize
these without additional interaction with the application.
When resizing windows, resize_term recursively adjusts subwindows,
keeping them within the updated parent window's limits. If a top-
level window happens to extend to the screen's limits, then on
resizing the window, resize_term will keep the window extending to
the corresponding limit, regardless of whether the screen has shrunk
A support function is_term_resized is provided so that applications
can check if the resize_term function would modify the window
structures. It returns TRUE if the windows would be modified, and
Except as noted, these functions return the integer ERR upon failure
and OK on success. They will fail if either of the dimensions are
less than or equal to zero, or if an error occurs while
(re)allocating memory for the windows.
While these functions are intended to be used to support a signal
handler (i.e., for SIGWINCH), care should be taken to avoid invoking
them in a context where malloc or realloc may have been interrupted,
since it uses those functions.
If ncurses is configured to supply its own SIGWINCH handler,
· on receipt of a SIGWINCH, the handler sets a flag
· which is tested in wgetch(3X) and doupdate,
· in turn, calling the resizeterm function,
· which ungetch's a KEY_RESIZE which will be read on the next call
The KEY_RESIZE alerts an application that the screen size has
changed, and that it should repaint special features such as pads
that cannot be done automatically.
Calling resizeterm or resize_term directly from a signal handler
is unsafe. This indirect method is used to provide a safe way to
resize the ncurses data structures.
If the environment variables LINES or COLUMNS are set, this overrides
the library's use of the window size obtained from the operating
system. Thus, even if a SIGWINCH is received, no screen size change
may be recorded.
It is possible to resize the screen with SVr4 curses, by
· exiting curses with endwin(3X) and
· resuming using refresh(3X).
Doing that clears the screen and is visually distracting.
This extension of ncurses was introduced in mid-1995. It was adopted
in NetBSD curses (2001) and PDCurses (2003).
This page is part of the ncurses (new curses) project. Information
about the project can be found at
⟨https://www.gnu.org/software/ncurses/ncurses.html⟩. If you have a
bug report for this manual page, send it to
firstname.lastname@example.org. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-09.) If you discover any rendering problems in
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