curs_variables(3x) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | NOTES | PORTABILITY | SEE ALSO | COLOPHON

curs_variables(3X)                                    curs_variables(3X)

NAME         top

       COLORS, COLOR_PAIRS, COLS, ESCDELAY, LINES, TABSIZE, curscr,
       newscr, stdscr - curses global variables

SYNOPSIS         top

       #include <curses.h>

       int COLOR_PAIRS;
       int COLORS;
       int COLS;
       int ESCDELAY;
       int LINES;
       int TABSIZE;
       WINDOW * curscr;
       WINDOW * newscr;
       WINDOW * stdscr;

DESCRIPTION         top

       This page summarizes variables provided by the curses library.  A
       more complete description is given in the curses(3X) manual page.

       Depending on the configuration, these may be actual variables, or
       macros (see curs_threads(3X) and curs_opaque(3X)) which provide
       read-only access to curses's state.  In either case, applications
       should treat them as read-only to avoid confusing the library.

   COLOR_PAIRS
       After initializing curses, this variable contains the number of
       color pairs which the terminal can support.  Usually the number
       of color pairs will be the product COLORS*COLORS, however this is
       not always true:

       •   a few terminals use HLS colors, which do not follow this rule

       •   terminals supporting a large number of colors are limited by
           the number of color pairs that can be represented in a signed
           short value.

   COLORS
       After initializing curses, this variable contains the number of
       colors which the terminal can support.

   COLS
       After initializing curses, this variable contains the width of
       the screen, i.e., the number of columns.

   ESCDELAY
       This variable holds the number of milliseconds to wait after
       reading an escape character, to distinguish between an individual
       escape character entered on the keyboard from escape sequences
       sent by cursor- and function-keys (see curses(3X)).

   LINES
       After initializing curses, this variable contains the height of
       the screen, i.e., the number of lines.

   TABSIZE
       This variable holds the number of columns used by the curses
       library when converting a tab character to spaces as it adds the
       tab to a window (see curs_addch(3X).

   The Current Screen
       This implementation of curses uses a special window curscr to
       record its updates to the terminal screen.

       This is referred to as the “physical screen” in the
       curs_refresh(3X) and curs_outopts(3X) manual pages.

   The New Screen
       This implementation of curses uses a special window newscr to
       hold updates to the terminal screen before applying them to
       curscr.

       This is referred to as the “virtual screen” in the
       curs_kernel(3X), curs_refresh(3X) and curs_outopts(3X) manual
       pages.

   The Standard Screen
       Upon initializing curses, a default window called stdscr, which
       is the size of the terminal screen, is created.  Many curses
       functions use this window.

NOTES         top

       The curses library is initialized using either initscr(3X), or
       newterm(3X).

       If curses is configured to use separate curses/terminfo
       libraries, most of these variables reside in the curses library.

PORTABILITY         top

       TABSIZE is a feature of SVr4 curses which is not documented by
       X/Open curses.

       •   In SVr4 curses, TABSIZE is initially set from the terminal
           description's init_tabs capability.  After that, it can be
           altered by the applications using SVr4 curses.

           SVr4 curses uses the current value of TABSIZE to compute the
           position of tabstops for updating both the virtual screen
           with addch(3X) as well as the physical screen with mvcur(3X).

       •   This implementation uses the current value of TABSIZE only
           for updating the virtual screen.  It uses the terminal
           description's it (init_tabs) capability for computing
           hardware tabs (i.e., tab stops on the physical screen).

       •   Other implementations differ.  For instance, NetBSD curses
           allows TABSIZE to be set through an environment variable.
           This implementation does not.

           NetBSD curses does not support hardware tabs; it uses the
           init_tabs capability and the TABSIZE variable only for
           updating the virtual screen.

       ESCDELAY is an extension in AIX curses:

       •   In AIX, the units for ESCDELAY are fifths of a millisecond.

       •   The default value for AIX's ESCDELAY is 0.1 seconds.

       •   AIX also enforces a limit of 10,000 seconds for ESCDELAY;
           this implementation currently has no upper limit.

       This implementation has long used ESCDELAY with units of
       milliseconds, making it impossible to be completely compatible
       with AIX.  Likewise, most users have either decided to override
       the value, or rely upon its default value.

SEE ALSO         top

       curses(3X), curs_opaque(3X), curs_terminfo(3X), curs_threads(3X),
       term_variables(3X), terminfo(5).

COLOPHON         top

       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
       bug-ncurses-request@gnu.org.  This page was obtained from the
       project's upstream Git mirror of the CVS repository
       ⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2021-06-20.  (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
       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

                                                      curs_variables(3X)