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ncurses(3)                      Library calls                     ncurses(3)


       ncurses - character-cell terminal interface with optimized output


       #include <curses.h>


       The "new curses" library offers the programmer a terminal-independent
       means of reading keyboard and mouse input and updating character-cell
       terminals with output optimized to minimize screen updates.  ncurses
       replaces the curses libraries from System V Release 4 Unix ("SVr4") and
       4.4BSD Unix, the development of which ceased in the 1990s.  This
       document describes ncurses version 6.5 (patch 20240427).

       ncurses permits control of the terminal screen's contents; abstraction
       and subdivision thereof with windows and pads; the reading of terminal
       input; control of terminal input and output options; environment query
       routines; color manipulation; the definition and use of soft label
       keys; terminfo capability access; a termcap compatibility interface;
       and an abstraction of the system's API for manipulating the terminal
       (such as termios(3)).

       ncurses implements the standard interface described by X/Open Curses
       Issue 7.  In many behavioral details not standardized by X/Open,
       ncurses emulates the curses library of SVr4 and provides numerous
       useful extensions.

       ncurses man pages employ several sections to clarify matters of usage
       and interoperability with other curses implementations.

       o   "NOTES" describes issues and caveats of which any user of the
           ncurses API should be aware, such as limitations on the size of an
           underlying integral type or the availability of a preprocessor
           macro exclusive of a function definition (which prevents its
           address from being taken).  This section also describes
           implementation details that will be significant to the programmer
           but which are not standardized.

       o   "EXTENSIONS" presents ncurses innovations beyond the X/Open Curses
           standard and/or the SVr4 curses implementation.  They are termed
           extensions to indicate that they cannot be implemented solely by
           using the library API, but require access to the library's internal

       o   "PORTABILITY" discusses matters (beyond the exercise of extensions)
           that should be considered when writing to a curses standard, or for
           multiple implementations.

       o   "HISTORY" examines points of detail in ncurses and other curses
           implementations over the decades of their development, particularly
           where precedent or inertia have frustrated better design (and, in a
           few cases, where such inertia has been overcome).

       A curses application must be linked with the library; use the -lncurses
       option to your compiler or linker.  A debugging version of the library
       may be available; if so, link with it using -lncurses_g.  (Your system
       integrator may have installed these libraries such that you can use the
       options -lcurses and -lcurses_g, respectively.)  The ncurses_g library
       generates trace logs (in a file called trace in the current directory)
       that describe ncurses actions.  See section "ALTERNATE CONFIGURATIONS"

   Application Structure
       A curses application uses information from the system locale;
       setlocale(3) prepares it for curses library calls.

           setlocale(LC_ALL, "");

       If the locale is not thus initialized, the library assumes that
       characters are printable as in ISO 8859-1, to work with certain legacy
       programs.  You should initialize the locale; do not expect consistent
       behavior from the library when the locale has not been set up.

       initscr(3X) or newterm(3X) must be called to initialize curses before
       use of any functions that deal with windows and screens.

       To get character-at-a-time input without echoing--most interactive,
       screen-oriented programs want this--use the following sequence.

           initscr(); cbreak(); noecho();

       Most applications perform further setup as follows.

           intrflush(stdscr, FALSE);
           keypad(stdscr, TRUE);

       A curses program then often enters an event loop of some sort.  Call
       endwin(3X) before exiting.

       A curses library abstracts the terminal screen by representing all or
       part of it as a WINDOW data structure.  A window is a rectangular grid
       of character cells, addressed by row and column coordinates (y, x),
       with the upper left corner as (0, 0).  A window called stdscr, the same
       size as the terminal screen, is always available.  Create others with

       A curses library does not manage overlapping windows (but see below).
       You can either use stdscr to manage one screen-filling window, or tile
       the screen into non-overlapping windows and not use stdscr at all.
       Mixing the two approaches will result in unpredictable and undesired

       Functions permit manipulation of a window and the cursor identifying
       the cell within it at which the next output operation will occur.
       Among those, the most basic are move(3X) and addch(3X): these place the
       cursor and write a character to stdscr, respectively.

       Frequent changes to the terminal screen can cause unpleasant flicker or
       inefficient use of the communication channel to the device, so the
       library does not generally update it automatically.  Therefore, after
       using curses functions to accumulate a set of desired updates that make
       sense to present together, call refresh(3X) to tell the library to make
       the user's screen look like stdscr.  The library optimizes its output
       by computing a minimal number of operations to mutate the screen from
       its state at the previous refresh to the new one.  Effective
       optimization demands accurate information about the terminal device:
       the management of such information is the province of the terminfo(3X)
       API, a feature of every standard curses implementation.

       Special windows called pads may also be manipulated.  These are windows
       that are not constrained to the size of the terminal screen and whose
       contents need not be completely displayed.  See curs_pad(3X).

       In addition to drawing characters on the screen, rendering attributes
       and colors may be supported, causing the characters to show up in such
       modes as underlined, in reverse video, or in color on terminals that
       support such display enhancements.  See curs_attr(3X).

       curses predefines constants for a small set of forms-drawing graphics
       corresponding to the DEC Alternate Character Set (ACS), a feature of
       VT100 and other terminals.  See waddch(3X).

       curses is implemented using the operating system's terminal driver;
       keystroke events are received not as scan codes but as byte sequences.
       Graphical keycaps (alphanumeric and punctuation keys, and the space)
       appear as-is.  Everything else, including the tab, enter/return,
       keypad, arrow, and function keys, appears as a control character or a
       multibyte escape sequence.  curses translates these into unique key
       codes.  See getch(3X).

       ncurses provides reimplementations of the SVr4 panel(3X), form(3X), and
       menu(3X) libraries to ease construction of user interfaces with curses.

       The selection of an appropriate value of TERM in the process
       environment is essential to correct curses and terminfo library
       operation.  A well-configured system selects a correct TERM value
       automatically; tset(1) may assist with troubleshooting exotic

       If you change the terminal type, export the TERM environment variable
       in the shell, then run tset(1) or the "tput init" command.  See
       subsection "Tabs and Initialization" of terminfo(5).

       If the environment variables LINES and COLUMNS are set, or if the
       curses program is executing in a graphical windowing environment, the
       information obtained thence overrides that obtained by terminfo.  An
       ncurses extension supports resizable terminals; see wresize(3X).

       If the environment variable TERMINFO is defined, a curses program
       checks first for a terminal type description in the location it
       identifies.  TERMINFO is useful for developing experimental type
       descriptions or when write permission to /opt/local/share/terminfo is
       not available.

       See section "ENVIRONMENT" below.

   Naming Conventions
       curses offers many functions in variant forms using a regular set of
       alternatives to the name of an elemental one.  Those prefixed with "w"
       require a WINDOW pointer argument; those with a "mv" prefix first
       perform cursor movement using wmove(3X); a "mvw" prefix indicates both.
       The "w" function is typically the elemental one; the removal of this
       prefix usually indicates operation on stdscr.

       Four functions prefixed with "p" require a pad argument.

       In function synopses, ncurses man pages apply the following names to

                       bf    bool (TRUE or FALSE)
                       c     a char or int
                       ch    a chtype
                       wc    a wchar_t or wint_t
                       wch   a cchar_t
                       win   pointer to a WINDOW
                       pad   pointer to a WINDOW that is a pad

   Wide and Non-wide Character Configurations
       This manual page describes functions that appear in any configuration
       of the library.  There are two common configurations; see section

       ncurses   is the library in its "non-wide" configuration, handling only
                 eight-bit characters.  It stores a character combined with
                 attributes in a chtype datum, which is often an alias of int.

                 Attributes alone (with no corresponding character) can be
                 stored in variables of chtype or attr_t type.  In either
                 case, they are represented as an integral bit mask.

                 Each cell of a WINDOW is stored as a chtype.

       ncursesw  is the library in its "wide" configuration, which handles
                 character encodings requiring a larger data type than char (a
                 byte-sized type) can represent.  It adds about one third more
                 calls using additional data types that can store such
                 multibyte characters.

                 cchar_t  corresponds to the non-wide configuration's chtype.
                          It always a structure type, because it stores more
                          data than fit into a standard scalar type.  A
                          character code may not be representable as a char,
                          and moreover more than one character may occupy a
                          cell (as with accent marks and other diacritics).
                          Each character is of type wchar_t; a complex
                          character contains one spacing character and zero or
                          more non-spacing characters (see below).  Attributes
                          and color data are stored in separate fields of the
                          structure, not combined as in chtype.

                 Each cell of a WINDOW is stored as a cchar_t.

                 setcchar(3X) and getcchar(3X) store and retrieve cchar_t
                 data.  The wide library API of ncurses depends on two data
                 types standardized by ISO C95.

                 wchar_t  stores a wide character.  Like chtype, it may be an
                          alias of int.  Depending on the character encoding,
                          a wide character may be spacing, meaning that it
                          occupies a character cell by itself and typically
                          accompanies cursor advancement, or non-spacing,
                          meaning that it occupies the same cell as a spacing
                          character, is often regarded as a "modifier" of the
                          base glyph with which it combines, and typically
                          does not advance the cursor.

                 wint_t   can store a wchar_t or the constant WEOF,
                          analogously to the int-sized character manipulation
                          functions of ISO C and its constant EOF.

                 The wide library provides additional functions that
                 complement those in the non-wide library where the size of
                 the underlying character type is significant.  A somewhat
                 regular naming convention relates many of the wide variants
                 to their non-wide counterparts; where a non-wide function
                 name contains "ch" or "str", prefix it with "_w" to obtain
                 the wide counterpart.  For example, waddch becomes wadd_wch.
                 (Exceptions that add only "w" comprise addwstr, inwstr, and
                 their variants.)

                 This convention is inapplicable to some non-wide function
                 names, so other transformations are used for the wide
                 configuration: the window background management function
                 "bkgd" becomes "bkgrnd"; the window border-drawing and
                 -clearing functions are suffixed with "_set"; and character
                 attribute manipulation functions like "attron" become

   Function Name Index
       The following table lists the curses functions provided in the non-wide
       and wide APIs and the corresponding man pages that describe them.
       Those flagged with "*" are ncurses-specific, neither described by
       X/Open Curses nor present in SVr4.

                    curses Function Name     Man Page
                    COLOR_PAIR               curs_color(3X)
                    PAIR_NUMBER              curs_color(3X)
                    add_wch                  curs_add_wch(3X)
                    add_wchnstr              curs_add_wchstr(3X)
                    add_wchstr               curs_add_wchstr(3X)
                    addch                    curs_addch(3X)
                    addchnstr                curs_addchstr(3X)
                    addchstr                 curs_addchstr(3X)
                    addnstr                  curs_addstr(3X)
                    addnwstr                 curs_addwstr(3X)
                    addstr                   curs_addstr(3X)
                    addwstr                  curs_addwstr(3X)
                    alloc_pair               new_pair(3X)*
                    assume_default_colors    default_colors(3X)*
                    attr_get                 curs_attr(3X)
                    attr_off                 curs_attr(3X)
                    attr_on                  curs_attr(3X)
                    attr_set                 curs_attr(3X)
                    attroff                  curs_attr(3X)
                    attron                   curs_attr(3X)
                    attrset                  curs_attr(3X)
                    baudrate                 curs_termattrs(3X)
                    beep                     curs_beep(3X)
                    bkgd                     curs_bkgd(3X)
                    bkgdset                  curs_bkgd(3X)
                    bkgrnd                   curs_bkgrnd(3X)
                    bkgrndset                curs_bkgrnd(3X)
                    border                   curs_border(3X)
                    border_set               curs_border_set(3X)
                    box                      curs_border(3X)
                    box_set                  curs_border_set(3X)
                    can_change_color         curs_color(3X)
                    cbreak                   curs_inopts(3X)
                    chgat                    curs_attr(3X)
                    clear                    curs_clear(3X)
                    clearok                  curs_outopts(3X)
                    clrtobot                 curs_clear(3X)
                    clrtoeol                 curs_clear(3X)
                    color_content            curs_color(3X)
                    color_set                curs_attr(3X)
                    copywin                  curs_overlay(3X)
                    curs_set                 curs_kernel(3X)
                    curses_trace             curs_trace(3X)*
                    curses_version           curs_extend(3X)*
                    def_prog_mode            curs_kernel(3X)
                    def_shell_mode           curs_kernel(3X)
                    define_key               define_key(3X)*
                    del_curterm              curs_terminfo(3X)
                    delay_output             curs_util(3X)
                    delch                    curs_delch(3X)
                    deleteln                 curs_deleteln(3X)
                    delscreen                curs_initscr(3X)
                    delwin                   curs_window(3X)
                    derwin                   curs_window(3X)
                    doupdate                 curs_refresh(3X)
                    dupwin                   curs_window(3X)
                    echo                     curs_inopts(3X)
                    echo_wchar               curs_add_wch(3X)
                    echochar                 curs_addch(3X)
                    endwin                   curs_initscr(3X)
                    erase                    curs_clear(3X)
                    erasechar                curs_termattrs(3X)
                    erasewchar               curs_termattrs(3X)
                    exit_curses              curs_memleaks(3X)*
                    exit_terminfo            curs_memleaks(3X)*
                    extended_color_content   curs_color(3X)*
                    extended_pair_content    curs_color(3X)*
                    extended_slk_color       curs_slk(3X)*
                    filter                   curs_util(3X)
                    find_pair                new_pair(3X)*
                    flash                    curs_beep(3X)
                    flushinp                 curs_util(3X)
                    free_pair                new_pair(3X)*
                    get_escdelay             curs_threads(3X)*
                    get_wch                  curs_get_wch(3X)
                    get_wstr                 curs_get_wstr(3X)
                    getattrs                 curs_attr(3X)
                    getbegx                  curs_legacy(3X)*
                    getbegy                  curs_legacy(3X)*
                    getbegyx                 curs_getyx(3X)
                    getbkgd                  curs_bkgd(3X)
                    getbkgrnd                curs_bkgrnd(3X)
                    getcchar                 curs_getcchar(3X)
                    getch                    curs_getch(3X)
                    getcurx                  curs_legacy(3X)*
                    getcury                  curs_legacy(3X)*
                    getmaxx                  curs_legacy(3X)*
                    getmaxy                  curs_legacy(3X)*
                    getmaxyx                 curs_getyx(3X)
                    getmouse                 curs_mouse(3X)*
                    getn_wstr                curs_get_wstr(3X)
                    getnstr                  curs_getstr(3X)
                    getparx                  curs_legacy(3X)*
                    getpary                  curs_legacy(3X)*
                    getparyx                 curs_getyx(3X)
                    getstr                   curs_getstr(3X)
                    getsyx                   curs_kernel(3X)
                    getwin                   curs_util(3X)
                    getyx                    curs_getyx(3X)
                    halfdelay                curs_inopts(3X)
                    has_colors               curs_color(3X)
                    has_ic                   curs_termattrs(3X)
                    has_il                   curs_termattrs(3X)
                    has_key                  curs_getch(3X)*
                    has_mouse                curs_mouse(3X)*
                    hline                    curs_border(3X)
                    hline_set                curs_border_set(3X)
                    idcok                    curs_outopts(3X)
                    idlok                    curs_outopts(3X)
                    immedok                  curs_outopts(3X)
                    in_wch                   curs_in_wch(3X)
                    in_wchnstr               curs_in_wchstr(3X)
                    in_wchstr                curs_in_wchstr(3X)
                    inch                     curs_inch(3X)
                    inchnstr                 curs_inchstr(3X)
                    inchstr                  curs_inchstr(3X)
                    init_color               curs_color(3X)
                    init_extended_color      curs_color(3X)*
                    init_extended_pair       curs_color(3X)*
                    init_pair                curs_color(3X)
                    initscr                  curs_initscr(3X)
                    innstr                   curs_instr(3X)
                    innwstr                  curs_inwstr(3X)
                    ins_nwstr                curs_ins_wstr(3X)
                    ins_wch                  curs_ins_wch(3X)
                    ins_wstr                 curs_ins_wstr(3X)
                    insch                    curs_insch(3X)
                    insdelln                 curs_deleteln(3X)
                    insertln                 curs_deleteln(3X)
                    insnstr                  curs_insstr(3X)
                    insstr                   curs_insstr(3X)
                    instr                    curs_instr(3X)
                    intrflush                curs_inopts(3X)
                    inwstr                   curs_inwstr(3X)
                    is_cbreak                curs_inopts(3X)*
                    is_cleared               curs_opaque(3X)*
                    is_echo                  curs_inopts(3X)*
                    is_idcok                 curs_opaque(3X)*
                    is_idlok                 curs_opaque(3X)*
                    is_immedok               curs_opaque(3X)*
                    is_keypad                curs_opaque(3X)*
                    is_leaveok               curs_opaque(3X)*
                    is_linetouched           curs_touch(3X)
                    is_nl                    curs_inopts(3X)*
                    is_nodelay               curs_opaque(3X)*
                    is_notimeout             curs_opaque(3X)*
                    is_pad                   curs_opaque(3X)*
                    is_raw                   curs_inopts(3X)*
                    is_scrollok              curs_opaque(3X)*
                    is_subwin                curs_opaque(3X)*
                    is_syncok                curs_opaque(3X)*
                    is_term_resized          resizeterm(3X)*
                    is_wintouched            curs_touch(3X)
                    isendwin                 curs_initscr(3X)
                    key_defined              key_defined(3X)*
                    key_name                 curs_util(3X)
                    keybound                 keybound(3X)*
                    keyname                  curs_util(3X)
                    keyok                    keyok(3X)*
                    keypad                   curs_inopts(3X)
                    killchar                 curs_termattrs(3X)
                    killwchar                curs_termattrs(3X)
                    leaveok                  curs_outopts(3X)
                    longname                 curs_termattrs(3X)
                    mcprint                  curs_print(3X)*
                    meta                     curs_inopts(3X)
                    mouse_trafo              curs_mouse(3X)*
                    mouseinterval            curs_mouse(3X)*
                    mousemask                curs_mouse(3X)*
                    move                     curs_move(3X)
                    mvadd_wch                curs_add_wch(3X)
                    mvadd_wchnstr            curs_add_wchstr(3X)
                    mvadd_wchstr             curs_add_wchstr(3X)
                    mvaddch                  curs_addch(3X)
                    mvaddchnstr              curs_addchstr(3X)
                    mvaddchstr               curs_addchstr(3X)
                    mvaddnstr                curs_addstr(3X)
                    mvaddnwstr               curs_addwstr(3X)
                    mvaddstr                 curs_addstr(3X)
                    mvaddwstr                curs_addwstr(3X)
                    mvchgat                  curs_attr(3X)
                    mvcur                    curs_terminfo(3X)
                    mvdelch                  curs_delch(3X)
                    mvderwin                 curs_window(3X)
                    mvget_wch                curs_get_wch(3X)
                    mvget_wstr               curs_get_wstr(3X)
                    mvgetch                  curs_getch(3X)
                    mvgetn_wstr              curs_get_wstr(3X)
                    mvgetnstr                curs_getstr(3X)
                    mvgetstr                 curs_getstr(3X)
                    mvhline                  curs_border(3X)
                    mvhline_set              curs_border_set(3X)
                    mvin_wch                 curs_in_wch(3X)
                    mvin_wchnstr             curs_in_wchstr(3X)
                    mvin_wchstr              curs_in_wchstr(3X)
                    mvinch                   curs_inch(3X)
                    mvinchnstr               curs_inchstr(3X)
                    mvinchstr                curs_inchstr(3X)
                    mvinnstr                 curs_instr(3X)
                    mvinnwstr                curs_inwstr(3X)
                    mvins_nwstr              curs_ins_wstr(3X)
                    mvins_wch                curs_ins_wch(3X)
                    mvins_wstr               curs_ins_wstr(3X)
                    mvinsch                  curs_insch(3X)
                    mvinsnstr                curs_insstr(3X)
                    mvinsstr                 curs_insstr(3X)
                    mvinstr                  curs_instr(3X)
                    mvinwstr                 curs_inwstr(3X)
                    mvprintw                 curs_printw(3X)
                    mvscanw                  curs_scanw(3X)
                    mvvline                  curs_border(3X)
                    mvvline_set              curs_border_set(3X)
                    mvwadd_wch               curs_add_wch(3X)
                    mvwadd_wchnstr           curs_add_wchstr(3X)
                    mvwadd_wchstr            curs_add_wchstr(3X)
                    mvwaddch                 curs_addch(3X)
                    mvwaddchnstr             curs_addchstr(3X)
                    mvwaddchstr              curs_addchstr(3X)
                    mvwaddnstr               curs_addstr(3X)
                    mvwaddnwstr              curs_addwstr(3X)
                    mvwaddstr                curs_addstr(3X)
                    mvwaddwstr               curs_addwstr(3X)
                    mvwchgat                 curs_attr(3X)
                    mvwdelch                 curs_delch(3X)
                    mvwget_wch               curs_get_wch(3X)
                    mvwget_wstr              curs_get_wstr(3X)
                    mvwgetch                 curs_getch(3X)
                    mvwgetn_wstr             curs_get_wstr(3X)
                    mvwgetnstr               curs_getstr(3X)
                    mvwgetstr                curs_getstr(3X)
                    mvwhline                 curs_border(3X)
                    mvwhline_set             curs_border_set(3X)
                    mvwin                    curs_window(3X)
                    mvwin_wch                curs_in_wch(3X)
                    mvwin_wchnstr            curs_in_wchstr(3X)
                    mvwin_wchstr             curs_in_wchstr(3X)
                    mvwinch                  curs_inch(3X)
                    mvwinchnstr              curs_inchstr(3X)
                    mvwinchstr               curs_inchstr(3X)
                    mvwinnstr                curs_instr(3X)
                    mvwinnwstr               curs_inwstr(3X)
                    mvwins_nwstr             curs_ins_wstr(3X)
                    mvwins_wch               curs_ins_wch(3X)
                    mvwins_wstr              curs_ins_wstr(3X)
                    mvwinsch                 curs_insch(3X)
                    mvwinsnstr               curs_insstr(3X)
                    mvwinsstr                curs_insstr(3X)
                    mvwinstr                 curs_instr(3X)
                    mvwinwstr                curs_inwstr(3X)
                    mvwprintw                curs_printw(3X)
                    mvwscanw                 curs_scanw(3X)
                    mvwvline                 curs_border(3X)
                    mvwvline_set             curs_border_set(3X)
                    napms                    curs_kernel(3X)
                    newpad                   curs_pad(3X)
                    newterm                  curs_initscr(3X)
                    newwin                   curs_window(3X)
                    nl                       curs_inopts(3X)
                    nocbreak                 curs_inopts(3X)
                    nodelay                  curs_inopts(3X)
                    noecho                   curs_inopts(3X)
                    nofilter                 curs_util(3X)*
                    nonl                     curs_inopts(3X)
                    noqiflush                curs_inopts(3X)
                    noraw                    curs_inopts(3X)
                    notimeout                curs_inopts(3X)
                    overlay                  curs_overlay(3X)
                    overwrite                curs_overlay(3X)
                    pair_content             curs_color(3X)
                    pecho_wchar              curs_pad(3X)
                    pechochar                curs_pad(3X)
                    pnoutrefresh             curs_pad(3X)
                    prefresh                 curs_pad(3X)
                    printw                   curs_printw(3X)
                    putp                     curs_terminfo(3X)
                    putwin                   curs_util(3X)
                    qiflush                  curs_inopts(3X)
                    raw                      curs_inopts(3X)
                    redrawwin                curs_refresh(3X)
                    refresh                  curs_refresh(3X)
                    reset_color_pairs        curs_color(3X)*
                    reset_prog_mode          curs_kernel(3X)
                    reset_shell_mode         curs_kernel(3X)
                    resetty                  curs_kernel(3X)
                    resize_term              resizeterm(3X)*
                    resizeterm               resizeterm(3X)*
                    restartterm              curs_terminfo(3X)
                    ripoffline               curs_kernel(3X)
                    savetty                  curs_kernel(3X)
                    scanw                    curs_scanw(3X)
                    scr_dump                 curs_scr_dump(3X)
                    scr_init                 curs_scr_dump(3X)
                    scr_restore              curs_scr_dump(3X)
                    scr_set                  curs_scr_dump(3X)
                    scrl                     curs_scroll(3X)
                    scroll                   curs_scroll(3X)
                    scrollok                 curs_outopts(3X)
                    set_curterm              curs_terminfo(3X)
                    set_escdelay             curs_threads(3X)*
                    set_tabsize              curs_threads(3X)*
                    set_term                 curs_initscr(3X)
                    setcchar                 curs_getcchar(3X)
                    setscrreg                curs_outopts(3X)
                    setsyx                   curs_kernel(3X)
                    setupterm                curs_terminfo(3X)
                    slk_attr                 curs_slk(3X)*
                    slk_attr_off             curs_slk(3X)
                    slk_attr_on              curs_slk(3X)
                    slk_attr_set             curs_slk(3X)
                    slk_attroff              curs_slk(3X)
                    slk_attron               curs_slk(3X)
                    slk_attrset              curs_slk(3X)
                    slk_clear                curs_slk(3X)
                    slk_color                curs_slk(3X)
                    slk_init                 curs_slk(3X)
                    slk_label                curs_slk(3X)
                    slk_noutrefresh          curs_slk(3X)
                    slk_refresh              curs_slk(3X)
                    slk_restore              curs_slk(3X)
                    slk_set                  curs_slk(3X)
                    slk_touch                curs_slk(3X)
                    slk_wset                 curs_slk(3X)
                    standend                 curs_attr(3X)
                    standout                 curs_attr(3X)
                    start_color              curs_color(3X)
                    subpad                   curs_pad(3X)
                    subwin                   curs_window(3X)
                    syncok                   curs_window(3X)
                    term_attrs               curs_termattrs(3X)
                    termattrs                curs_termattrs(3X)
                    termname                 curs_termattrs(3X)
                    tgetent                  curs_termcap(3X)
                    tgetflag                 curs_termcap(3X)
                    tgetnum                  curs_termcap(3X)
                    tgetstr                  curs_termcap(3X)
                    tgoto                    curs_termcap(3X)
                    tigetflag                curs_terminfo(3X)
                    tigetnum                 curs_terminfo(3X)
                    tigetstr                 curs_terminfo(3X)
                    timeout                  curs_inopts(3X)
                    tiparm                   curs_terminfo(3X)
                    tiparm_s                 curs_terminfo(3X)*
                    tiscan_s                 curs_terminfo(3X)*
                    touchline                curs_touch(3X)
                    touchwin                 curs_touch(3X)
                    tparm                    curs_terminfo(3X)
                    tputs                    curs_termcap(3X)
                    tputs                    curs_terminfo(3X)
                    trace                    curs_trace(3X)*
                    typeahead                curs_inopts(3X)
                    unctrl                   curs_util(3X)
                    unget_wch                curs_get_wch(3X)
                    ungetch                  curs_getch(3X)
                    ungetmouse               curs_mouse(3X)*
                    untouchwin               curs_touch(3X)
                    use_default_colors       default_colors(3X)*
                    use_env                  curs_util(3X)
                    use_extended_names       curs_extend(3X)*
                    use_legacy_coding        legacy_coding(3X)*
                    use_screen               curs_threads(3X)*
                    use_tioctl               curs_util(3X)*
                    use_window               curs_threads(3X)*
                    vid_attr                 curs_terminfo(3X)
                    vid_puts                 curs_terminfo(3X)
                    vidattr                  curs_terminfo(3X)
                    vidputs                  curs_terminfo(3X)
                    vline                    curs_border(3X)
                    vline_set                curs_border_set(3X)
                    vw_printw                curs_printw(3X)
                    vw_scanw                 curs_scanw(3X)
                    vwprintw                 curs_printw(3X)
                    vwscanw                  curs_scanw(3X)
                    wadd_wch                 curs_add_wch(3X)
                    wadd_wchnstr             curs_add_wchstr(3X)
                    wadd_wchstr              curs_add_wchstr(3X)
                    waddch                   curs_addch(3X)
                    waddchnstr               curs_addchstr(3X)
                    waddchstr                curs_addchstr(3X)
                    waddnstr                 curs_addstr(3X)
                    waddnwstr                curs_addwstr(3X)
                    waddstr                  curs_addstr(3X)
                    waddwstr                 curs_addwstr(3X)
                    wattr_get                curs_attr(3X)
                    wattr_off                curs_attr(3X)
                    wattr_on                 curs_attr(3X)
                    wattr_set                curs_attr(3X)
                    wattroff                 curs_attr(3X)
                    wattron                  curs_attr(3X)
                    wattrset                 curs_attr(3X)
                    wbkgd                    curs_bkgd(3X)
                    wbkgdset                 curs_bkgd(3X)
                    wbkgrnd                  curs_bkgrnd(3X)
                    wbkgrndset               curs_bkgrnd(3X)
                    wborder                  curs_border(3X)
                    wborder_set              curs_border_set(3X)
                    wchgat                   curs_attr(3X)
                    wclear                   curs_clear(3X)
                    wclrtobot                curs_clear(3X)
                    wclrtoeol                curs_clear(3X)
                    wcolor_set               curs_attr(3X)
                    wcursyncup               curs_window(3X)
                    wdelch                   curs_delch(3X)
                    wdeleteln                curs_deleteln(3X)
                    wecho_wchar              curs_add_wch(3X)
                    wechochar                curs_addch(3X)
                    wenclose                 curs_mouse(3X)*
                    werase                   curs_clear(3X)
                    wget_wch                 curs_get_wch(3X)
                    wget_wstr                curs_get_wstr(3X)
                    wgetbkgrnd               curs_bkgrnd(3X)
                    wgetch                   curs_getch(3X)
                    wgetdelay                curs_opaque(3X)*
                    wgetn_wstr               curs_get_wstr(3X)
                    wgetnstr                 curs_getstr(3X)
                    wgetparent               curs_opaque(3X)*
                    wgetscrreg               curs_opaque(3X)*
                    wgetstr                  curs_getstr(3X)
                    whline                   curs_border(3X)
                    whline_set               curs_border_set(3X)
                    win_wch                  curs_in_wch(3X)
                    win_wchnstr              curs_in_wchstr(3X)
                    win_wchstr               curs_in_wchstr(3X)
                    winch                    curs_inch(3X)
                    winchnstr                curs_inchstr(3X)
                    winchstr                 curs_inchstr(3X)
                    winnstr                  curs_instr(3X)
                    winnwstr                 curs_inwstr(3X)
                    wins_nwstr               curs_ins_wstr(3X)
                    wins_wch                 curs_ins_wch(3X)
                    wins_wstr                curs_ins_wstr(3X)
                    winsch                   curs_insch(3X)
                    winsdelln                curs_deleteln(3X)
                    winsertln                curs_deleteln(3X)
                    winsnstr                 curs_insstr(3X)
                    winsstr                  curs_insstr(3X)
                    winstr                   curs_instr(3X)
                    winwstr                  curs_inwstr(3X)
                    wmouse_trafo             curs_mouse(3X)*
                    wmove                    curs_move(3X)
                    wnoutrefresh             curs_refresh(3X)
                    wprintw                  curs_printw(3X)
                    wredrawln                curs_refresh(3X)
                    wrefresh                 curs_refresh(3X)
                    wresize                  wresize(3X)*
                    wscanw                   curs_scanw(3X)
                    wscrl                    curs_scroll(3X)
                    wsetscrreg               curs_outopts(3X)
                    wstandend                curs_attr(3X)
                    wstandout                curs_attr(3X)
                    wsyncdown                curs_window(3X)
                    wsyncup                  curs_window(3X)
                    wtimeout                 curs_inopts(3X)
                    wtouchln                 curs_touch(3X)
                    wunctrl                  curs_util(3X)
                    wvline                   curs_border(3X)
                    wvline_set               curs_border_set(3X)

       ncurses's screen-pointer extension adds additional functions
       corresponding to many of the above, each with an "_sp" suffix; see

       The availability of some extensions is configurable when ncurses is
       compiled; see sections "ALTERNATE CONFIGURATIONS" and "EXTENSIONS"


       Unless otherwise noted, functions that return an integer return OK on
       success and ERR on failure.  Functions that return pointers return NULL
       on failure.  Typically, ncurses treats a null pointer passed as a
       function parameter as a failure.  Functions prefixed with "mv" first
       perform cursor movement and fail if the position (y, x) is outside the
       window boundaries.


       The following symbols from the process environment customize the
       runtime behavior of ncurses applications.  The library may be
       configured to disregard the variables TERMINFO, TERMINFO_DIRS,
       TERMPATH, and HOME, if the user is the superuser (root), or the
       application uses setuid(2) or setgid(2).

       The debugging library checks this variable when the application has
       redirected output to a file.  Its integral value is used for the baud
       rate.  If that value is absent or invalid, ncurses uses 9600.  This
       feature allows testers to construct repeatable test cases that take
       into account optimization decisions that depend on baud rate.

   CC (command character)
       When set, the command_character (cmdch) capability value of loaded
       terminfo entries changes to the value of this variable.  Very few
       terminfo entries provide this feature.

       Because this name is also used in development environments to represent
       the C compiler's name, ncurses ignores its value if it is not one
       character in length.

       This variable specifies the width of the screen in characters.
       Applications running in a windowing environment usually are able to
       obtain the width of the window in which they are executing.  If COLUMNS
       is not defined and the terminal's screen size is not available from the
       terminal driver, ncurses uses the size specified by the columns (cols)
       capability of the terminal type's entry in the terminfo database, if

       It is important that your application use the correct screen size.
       Automatic detection thereof is not always possible because an
       application may be running on a host that does not honor NAWS
       (Negotiations About Window Size) or as a different user ID than the
       owner of the terminal device file.  Setting COLUMNS and/or LINES
       overrides the library's use of the screen size obtained from the
       operating system.

       The COLUMNS and LINES variables may be specified independently.  This
       property is useful to circumvent misfeatures of legacy terminal type
       descriptions; xterm(1) descriptions specifying 65 lines were once
       notorious.  For best results, avoid specifying cols and lines
       capability codes in terminfo descriptions of terminal emulators.

       use_env(3X) can disable use of the process environment in determining
       the screen size.  use_tioctl(3X) can update COLUMNS and LINES to match
       the screen size obtained from system calls or the terminal database.

       For curses to distinguish the ESC character resulting from a user's
       press of the "Escape" key on the input device from one beginning an
       escape sequence (as commonly produced by function keys), it waits after
       receiving the escape character to see if further characters are
       available on the input stream within a short interval.  A global
       variable ESCDELAY stores this interval in milliseconds.  The default
       value of 1000 (one second) is adequate for most uses.  This environment
       variable overrides it.

       The most common instance where you may wish to change this value is to
       work with a remote host over a slow communication channel.  If the host
       running a curses application does not receive the characters of an
       escape sequence in a timely manner, the library can interpret them as
       multiple key stroke events.

       xterm(1) mouse events are a form of escape sequence; therefore, if your
       application makes heavy use of multiple-clicking, you may wish to
       lengthen the default value because the delay applies to the composite
       multi-click event as well as the individual clicks.

       Portable applications should not rely upon the presence of ESCDELAY in
       either form, but setting the environment variable rather than the
       global variable does not create problems when compiling an application.

       If keypad(3X) is disabled for the curses window receiving input, a
       program must disambiguate escape sequences itself.

       ncurses may read and write auxiliary terminal descriptions in .termcap
       and .terminfo files in the user's home directory.

       This counterpart to COLUMNS specifies the height of the screen in
       characters.  The corresponding terminfo capability and code is lines.
       See the description of the COLUMNS variable above.

       (OS/2 EMX port only) OS/2 numbers a three-button mouse inconsistently
       with other platforms, such that 1 is the left button, 2 the right, and
       3 the middle.  This variable customizes the mouse button numbering.
       Its value must be three digits 1-3 in any order.  By default, ncurses
       assumes a numbering of "132".

       If set, this variable overrides the ncurses library's compiled-in
       assumption that the terminal's default colors are white on black; see
       default_colors(3X).  Set the foreground and background color values
       with this environment variable by assigning it two integer values
       separated by a comma, indicating foregound and background color
       numbers, respectively.

       For example, to tell ncurses not to assume anything about the colors,
       use a value of "-1,-1".  To make the default color scheme green on
       black, use "2,0".  ncurses accepts integral values from -1 up to the
       value of the terminfo max_colors (colors) capability.

       (MinGW port only) The Console2 program defectively handles the
       Microsoft Console API call CreateConsoleScreenBuffer.  Applications
       that use it will hang.  However, it is possible to simulate the action
       of this call by mapping coordinates, explicitly saving and restoring
       the original screen contents.  Setting the environment variable NCGDB
       has the same effect.

       (Linux only) When ncurses is configured to use the GPM interface, this
       variable may list one or more terminal names against which the TERM
       variable (see below) is matched.  An empty value disables the GPM
       interface, using ncurses's built-in support for xterm(1) mouse
       protocols instead.  If the variable is absent, ncurses attempts to open
       GPM if TERM contains "linux".

       ncurses may use tab characters in cursor movement optimization.  In
       some cases, your terminal driver may not handle them properly.  Set
       this environment variable to any value to disable the feature.  You can
       also adjust your stty(1) settings to avoid the problem.

       Many terminals store video attributes as a property of a character
       cell, as curses does.  Historically, some recorded changes in video
       attributes as data that logically occupies character cells on the
       display, switching attributes on or off, similarly to tags in a markup
       language; these are termed "magic cookies", and must be subsequently
       overprinted.  If the terminfo entry for your terminal type does not
       adequately describe its handling of magic cookies, set this variable to
       any value to instruct ncurses to disable attributes entirely.

       Most terminal type descriptions in the terminfo database detail
       hardware devices.  Many people use curses-based applications in
       terminal emulator programs that run in a windowing environment.  These
       programs can duplicate all of the important features of a hardware
       terminal, but often lack their limitations.  Chief among these absent
       drawbacks is the problem of data flow management; that is, limiting the
       speed of communication to what the hardware could handle.  Unless a
       hardware terminal is interfaced into a terminal concentrator (which
       does flow control), an application must manage flow control itself to
       prevent overruns and data loss.

       A solution that comes at no hardware cost is for an application to
       pause after directing a terminal to execute an operation that it
       performs slowly, such as clearing the display.  Many terminal type
       descriptions, including that for the VT100, embed delay specifications
       in capabilities.  You may wish to use these terminal descriptions
       without paying the performance penalty.  Set NCURSES_NO_PADDING to any
       value to disable all but mandatory padding.  Mandatory padding is used
       by such terminal capabilities as flash_screen (flash).

       (Obsolete) Prior to internal changes developed in ncurses 5.9 (patches
       20120825 through 20130126), the library used setbuf(3) to enable fully
       buffered output when initializing the terminal.  This was done, as in
       SVr4 curses, to increase performance.  For testing purposes, both of
       ncurses and of certain applications, this feature was made optional.
       Setting this variable disabled output buffering, leaving the output
       stream in the original (usually line-buffered) mode.

       Nowadays, ncurses performs its own buffering and does not require this
       workaround; it does not modify the buffering of the standard output
       stream.  This approach makes signal handling, as for interrupts, more
       robust.  A drawback is that certain unconventional programs mixed
       stdio(3) calls with ncurses calls and (usually) got the behavior they
       expected.  This is no longer the case; ncurses does not write to the
       standard output file descriptor through a stdio-buffered stream.

       As a special case, low-level API calls such as putp(3X) still use the
       standard output stream.  High-level curses calls such as printw(3X) do

       At initialization, ncurses inspects the TERM environment variable for
       special cases where VT100 forms-drawing characters (and the
       corresponding alternate character set terminfo capabilities) are known
       to be unsupported by terminal types that otherwise claim VT100
       compatibility.  Specifically, when running in a UTF-8 locale, the Linux
       virtual console device and the GNU screen(1) program ignore them.  Set
       this variable to a nonzero value to instruct ncurses that the
       terminal's ACS support is broken; the library then outputs Unicode code
       points that correspond to the forms-drawing characters.  Set it to zero
       (or a non-integer) to disable the special check for terminal type names
       matching "linux" or "screen", directing ncurses to assume that the ACS
       feature works if the terminal type description advertises it.

       As an alternative to use of this variable, ncurses checks for an
       extended terminfo numeric capability U8 that can be compiled using "tic
       -x".  Examples follow.

          # linux console, if patched to provide working
          # VT100 shift-in/shift-out, with corresponding font.
          linux-vt100|linux console with VT100 line-graphics,
                  U8#0, use=linux,

          # uxterm with vt100Graphics resource set to false
          xterm-utf8|xterm relying on UTF-8 line-graphics,
                  U8#1, use=xterm,

       The two-character name "U8" was chosen to permit its use via ncurses's
       termcap interface.

       At initialization, ncurses (in its debugging configuration) checks for
       this variable's presence.  If defined with an integral value, the
       library calls curses_trace(3X) with that value as the argument.

       The TERM variable denotes the terminal type.  Each is distinct, though
       many are similar.  It is commonly set by terminal emulators to help
       applications find a workable terminal description.  Some choose a
       popular approximation such as "ansi", "vt100", or "xterm" rather than
       an exact fit to their capabilities.  Not infrequently, an application
       will have problems with that approach; for example, a key stroke may
       not operate correctly, or produce no effect but seeming garbage
       characters on the screen.

       Setting TERM has no effect on hardware operation; it affects the way
       applications communicate with the terminal.  Likewise, as a general
       rule (xterm(1) being a rare exception), terminal emulators that allow
       you to specify TERM as a parameter or configuration value do not change
       their behavior to match that setting.

       If ncurses is configured with termcap support, it checks for a terminal
       type description in termcap format if one in terminfo format is not
       available.  Setting this variable directs ncurses to ignore the usual
       termcap database location, /etc/termcap; see TERMPATH below.  TERMCAP
       should contain either a terminal description (with newlines stripped
       out), or a file name indicating where the information required by the
       TERM environment variable is stored.

       ncurses can be configured to read terminal type description databases
       in various locations using different formats.  This variable overrides
       the default location.

       o   Descriptions in terminfo format are normally stored in a directory
           tree using subdirectories named by the common first letters of the
           terminal types named therein.  This is the scheme used in System V.

       o   If ncurses is configured to use hashed databases, then TERMINFO may
           name its location, such as /usr/share/terminfo.db, rather than

       The hashed database uses less disk space and is a little faster than
       the directory tree.  However, some applications assume the existence of
       the directory tree, and read it directly rather than using the terminfo

       o   If ncurses is configured with termcap support, this variable may
           contain the location of a termcap file.

       o   If the value of TERMINFO begins with "hex:" or "b64:", ncurses uses
           the remainder of the value as a compiled terminfo description.  You
           might produce the base64 format using infocmp(1M).

                  TERMINFO=$(infocmp -0 -Q2 -q)
                  export TERMINFO

           The compiled description is used only if it corresponds to the
           terminal type identified by TERM.

       Setting TERMINFO is the simplest, but not the only, way to direct
       ncurses to a terminal database.  The search path is as follows.

       o   the last terminal database to which the running ncurses application
           wrote, if any

       o   the location specified by the TERMINFO environment variable

       o   $HOME/.terminfo

       o   locations listed in the TERMINFO_DIRS environment variable

       o   location(s) configured and compiled into ncurses

          o   /opt/local/share/terminfo

       This variable specifies a list of locations, akin to PATH, in which
       ncurses searches for the terminal type descriptions described by
       TERMINFO above.  The list items are separated by colons on Unix and
       semicolons on OS/2 EMX.  System V terminfo lacks a corresponding
       feature; TERMINFO_DIRS is an ncurses extension.

       If TERMCAP does not hold a terminal type description or file name, then
       ncurses checks the contents of TERMPATH, a list of locations, akin to
       PATH, in which it searches for termcap terminal type descriptions.  The
       list items are separated by colons on Unix and semicolons on OS/2 EMX.

       If both TERMCAP and TERMPATH are unset or invalid, ncurses searches for
       the files /etc/termcap, /usr/share/misc/termcap, and $HOME/.termcap, in
       that order.


       Many different ncurses configurations are possible, determined by the
       options given to the configure script when building the library.  Run
       the script with the --help option to peruse them all.  A few are of
       particular significance to the application developer employing ncurses.

            The standard include for ncurses is as noted in SYNOPSIS:

                #include <curses.h>

            This option is used to avoid filename conflicts when ncurses is
            not the main implementation of curses of the computer.  If ncurses
            is installed disabling overwrite, it puts its headers in a
            subdirectory, e.g.,

                #include <ncurses/curses.h>

            It also omits a symbolic link which would allow you to use
            -lcurses to build executables.

            The configure script renames the library and (if the
            --disable-overwrite option is used) puts the header files in a
            different subdirectory.  All of the library names have a "w"
            appended to them, i.e., instead of


            you link with


            You must also enable the wide-character features in the header
            file when compiling for the wide-character library to use the
            extended (wide-character) functions.  The symbol which enables
            these features has changed since X/Open Curses, Issue 4:

            o   Originally, the wide-character feature required the symbol
                _XOPEN_SOURCE_EXTENDED but that was only valid for XPG4

            o   Later, that was deemed conflicting with _XOPEN_SOURCE defined
                to 500.

            o   As of mid-2018, none of the features in this implementation
                require a _XOPEN_SOURCE feature greater than 600.  However,
                X/Open Curses, Issue 7 (2009) recommends defining it to 700.

            o   Alternatively, you can enable the feature by defining
                NCURSES_WIDECHAR with the caveat that some other header file
                than curses.h may require a specific value for _XOPEN_SOURCE
                (or a system-specific symbol).

            The curses.h header file installed for the wide-character library
            is designed to be compatible with the non-wide library's header.
            Only the size of the WINDOW structure differs; few applications
            require more than pointers to WINDOWs.

            If the headers are installed allowing overwrite, the wide-
            character library's headers should be installed last, to allow
            applications to be built using either library from the same set of

            The configure script renames the library.  All of the library
            names have a "t" appended to them (before any "w" added by

            The global variables such as LINES are replaced by macros to allow
            read-only access.  At the same time, setter-functions are provided
            to set these values.  Some applications (very few) may require
            changes to work with this convention.




            The shared and normal (static) library names differ by their
            suffixes, e.g., and libncurses.a.  The debug and
            profiling libraries add a "_g" and a "_p" to the root names
            respectively, e.g., libncurses_g.a and libncurses_p.a.

            Low-level functions which do not depend upon whether the library
            supports wide-characters, are provided in the tinfo library.

            By doing this, it is possible to share the tinfo library between
            wide/normal configurations as well as reduce the size of the
            library when only low-level functions are needed.

            Those functions are described in these pages:

            o   curs_extend(3X) - miscellaneous curses extensions

            o   curs_inopts(3X) - curses input options

            o   curs_kernel(3X) - low-level curses routines

            o   curs_termattrs(3X) - curses environment query routines

            o   curs_termcap(3X) - curses emulation of termcap

            o   curs_terminfo(3X) - curses interface to terminfo database

            o   curs_util(3X) - miscellaneous curses utility routines

            The trace function normally resides in the debug library, but it
            is sometimes useful to configure this in the shared library.
            Configure scripts should check for the function's existence rather
            than assuming it is always in the debug library.


              tab stop initialization database

              compiled terminal capability database


       X/Open Curses permits most functions it specifies to be made available
       as macros as well.  ncurses does so

       o   for functions that return values via their parameters,

       o   to support obsolete features,

       o   to reuse functions (for example, those that move the cursor before
           another operation), and

       o   a few special cases.

       If the standard output file descriptor of an ncurses program is
       redirected to something that is not a terminal device, the library
       writes screen updates to the standard error file descriptor.  This was
       an undocumented feature of SVr3 curses.

       See subsection "Header Files" below regarding symbols exposed by
       inclusion of curses.h.


       ncurses enables an application to capture mouse events on certain
       terminals, including xterm(1); see curs_mouse(3X).

       ncurses provides a means of responding to window resizing events, as
       when running in a GUI terminal emulator application such as xterm; see
       resizeterm(3X) and wresize(3X).

       ncurses allows an application to query the terminal for the presence of
       a wide variety of special keys; see has_key(3X).

       ncurses extends the fixed set of function key capabilities specified by
       X/Open Curses by allowing the application programmer to define
       additional key events at runtime; see define_key(3X), key_defined(3X),
       keybound(3X), and keyok(3X).

       ncurses can exploit the capabilities of terminals implementing
       ISO 6429/ECMA-48 SGR 39 and SGR 49 sequences, which allow an
       application to reset the terminal to its original foreground and
       background colors.  From a user's perspective, the application is able
       to draw colored text on a background whose color is set independently,
       providing better control over color contrasts.  See default_colors(3X).

       An ncurses application can eschew knowledge of WINDOW structure
       internals, instead using accessor functions such as is_scrollok(3X).

       ncurses enables an application to direct application output to a
       printer attached to the terminal device; see curs_print(3X).

       ncurses offers slk_attr(3X) as a counterpart of attr_get(3X) for soft-
       label key lines, and extended_slk_color(3X) as a form of slk_color(3X)
       that can gather color information from them when many colors are

       Some extensions are available only if ncurses permits modification of
       unctrl(3X)'s behavior; see use_legacy_coding(3X).  ncurses is compiled
       to support them; section "ALTERNATE CONFIGURATIONS" describes how.

       o   Rudimentary support for multi-threaded applications may be
           available; see curs_threads(3X).

       o   Functions that ease the management of multiple screens can be
           exposed; see curs_sp_funcs(3X).

       o   To aid applications to debug their memory usage, ncurses optionally
           offers functions to more aggressively free memory it dynamically
           allocates itself; see curs_memleaks(3X).

       o   The library facilitates auditing and troubleshooting of its
           behavior; see curs_trace(3X).

       o   The compiler option -DUSE_GETCAP causes the library to fall back to
           reading /etc/termcap if the terminal setup code cannot find a
           terminfo entry corresponding to TERM.  Use of this feature is not
           recommended, as it essentially includes an entire termcap compiler
           in the ncurses startup code, at a cost in memory usage and
           application launch latency.

       PDCurses and NetBSD curses incorporate some ncurses extensions.
       Individual man pages indicate where this is the case.


       X/Open Curses defines two levels of conformance, "base" and "enhanced".
       The latter includes several additional features, such as wide-character
       and color support.  ncurses intends base-level conformance with X/Open
       Curses, and supports all features of its enhanced level except the
       untic utility.

       Differences between X/Open Curses and ncurses are documented in the
       "PORTABILITY" sections of applicable man pages.

   Error Checking
       In many cases, X/Open Curses is vague about error conditions, omitting
       some of the SVr4 documentation.

       Unlike other implementations, ncurses checks pointer parameters, such
       as those to WINDOW structures, to ensure that they are not null.  This
       is done primarily to guard against programmer error.  The standard
       interface does not provide a way for the library to tell an application
       which of several possible errors occurred.  Relying on this (or some
       other) extension adversely affects the portability of curses

   Padding Differences
       In historical curses implementations, delays embedded in the terminfo
       capabilities carriage_return (cr), scroll_forward (ind), cursor_left
       (cub1), form_feed (ff), and tab (ht) activated corresponding delay bits
       in the Unix terminal driver.  ncurses performs all padding by sending
       NUL bytes to the device.  This method is slightly more expensive, but
       narrows the interface to the Unix kernel significantly and
       correspondingly increases the package's portability.

   Header Files
       The header file curses.h itself includes the header files stdio.h and

       X/Open Curses has more to say,

           The inclusion of curses.h may make visible all symbols from the
           headers stdio.h, term.h, termios.h, and wchar.h.

       but does not finish the story.  A more complete account follows.

       o   Starting with 4BSD curses (1980) all implementations have provided
           a curses.h file.

           BSD curses code included curses.h and unctrl.h from an internal
           header file curses.ext, where "ext" abbreviated "externs".

           The implementations of printw and scanw used undocumented internal
           functions of the standard I/O library (_doprnt and _doscan), but
           nothing in curses.h itself relied upon stdio.h.

       o   SVr2 curses added newterm, which relies upon stdio.h because its
           function prototype employs the FILE type.

           SVr4 curses added putwin and getwin, which also use stdio.h.

           X/Open Curses specifies all three of these functions.

           SVr4 curses and X/Open Curses do not require the developer to
           include stdio.h before curses.h.  Both document use of curses as
           requiring only curses.h.

           As a result, standard curses.h always includes stdio.h.

       o   X/Open Curses and SVr4 curses are inconsistent with respect to

           As noted in curs_util(3X), ncurses includes unctrl.h from curses.h
           (as SVr4 does).

       o   X/Open Curses's comments about term.h and termios.h may refer to
           HP-UX and AIX.

           HP-UX curses includes term.h from curses.h to declare setupterm in
           curses.h, but ncurses and Solaris curses do not.

           AIX curses includes term.h and termios.h.  Again, ncurses and
           Solaris curses do not.

       o   X/Open Curses says that curses.h may include term.h, but does not
           require it to do so.

           Some programs use functions declared in both curses.h and term.h,
           and must include both header files in the same module.  Very old
           versions of AIX curses required inclusion of curses.h before

           The header files supplied by ncurses include the standard library
           headers required for its declarations, so ncurses's own header
           files can be included in any order.  But for portability, you
           should include curses.h before term.h.

       o   X/Open Curses says "may make visible" because including a header
           file does not necessarily make visible all of the symbols in it
           (consider #ifdef and similar).

           For instance, ncurses's curses.h may include wchar.h if the proper
           symbol is defined, and if ncurses is configured for wide-character
           support.  If wchar.h is included, its symbols may be made visible
           depending on the value of the _XOPEN_SOURCE feature test macro.

       o   X/Open Curses mandates an application's inclusion of one standard C
           library header in a special case: stdarg.h before curses.h to
           prototype the functions vw_printw and vw_scanw (as well as the
           obsolete vwprintw and vwscanw).  Each of these takes a variadic
           argument list, a va_list parameter, like that of printf(3).

           SVr3 curses introduced the two obsolete functions, and X/Open
           Curses the others.  In between, SVr4 curses provided for the
           possibility that an application might include either varargs.h or
           stdarg.h.  These represented contrasting approaches to handling
           variadic argument lists.  The older interface, varargs.h, used a
           pointer to char for variadic functions' va_list parameter.  Later,
           the list acquired its own standard data type, va_list, defined in
           stdarg.h, empowering the compiler to check the types of a function
           call's actual parameters against the formal ones declared in its

           No conforming implementations of X/Open Curses require an
           application to include stdarg.h before curses.h because they either
           have allowed for a special type, or, like ncurses, they include
           stdarg.h themselves to provide a portable interface.


       Zeyd M. Ben-Halim, Eric S. Raymond, Thomas E. Dickey.  Based on pcurses
       by Pavel Curtis.


       curs_variables(3X), terminfo(5), user_caps(5)

ncurses 6.5                       2024-04-27                       ncurses(3)

ncurses 6.5 - Generated Tue May 7 08:15:59 CDT 2024
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