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.,
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
When resizing the windows, resize_term blank-fills the areas that
are extended. The calling application should fill in these areas
with appropriate data.
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
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 or grown.
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 FALSE otherwise.
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 to wgetch.
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 2021-08-27. (At
that time, the date of the most recent commit that was found in
the repository was 2021-05-23.) If you discover any rendering
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