# ncurses 3x 2024-04-20 ncurses 6.4 Library calls

    ncurses(3x)                      Library calls                     ncurses(3x)

## NAME

           ncurses - character-cell terminal interface with optimized output

## SYNOPSIS

           #include <curses.h>

## DESCRIPTION

           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 6.4 (patch 20240420).

           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
               state.

           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"
           below.

### 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.

### Overview

           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
           newwin(3x).

           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
           effects.

           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.

### Initialization

           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
           situations.

           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 /usr/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
           parameters.

                           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
           "ALTERNATE CONFIGURATIONS" below.

           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
                     "attr_on".

### 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
           curs_sp_funcs(3x).

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

## RETURN VALUE

           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.

## ENVIRONMENT

           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).

### BAUDRATE

           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 term-
           info 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.

### COLUMNS

           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
           any.

           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.

### ESCDELAY

           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.

### HOME

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

### LINES

           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.

### MOUSE_BUTTONS_123

           (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".

### NCURSES_ASSUMED_COLORS

           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.

### NCURSES_CONSOLE2

           (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.

### NCURSES_GPM_TERMS

           (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_NO_HARD_TABS

           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.

### NCURSES_NO_MAGIC_COOKIE

           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.

### NCURSES_NO_PADDING

           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 temrinal 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).

### NCURSES_NO_SETBUF

           (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
           not.

### NCURSES_NO_UTF8_ACS

           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.

### NCURSES_TRACE

           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.

### TERM

           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.

### TERMCAP

           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.

### TERMINFO

           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
               /usr/share/terminfo/.

           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
           API.

           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   /usr/share/terminfo

### TERMINFO_DIRS

           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.

### TERMPATH

           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.

## ALTERNATE CONFIGURATIONS

           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.

           --disable-overwrite
                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.

           --enable-widec
                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

                    -lncurses

                you link with

                    -lncursesw

                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
                    (1996).

                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
                headers.

           --with-pthread
                The configure script renames the  library.   All  of  the  library
                names  have  a  "t"  appended  to  them  (before  any "w" added by
                --enable-widec).

                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.

           --with-shared
           --with-normal
           --with-debug
           --with-profile
                The  shared  and  normal  (static)  library  names differ by their
                suffixes, e.g., libncurses.so 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.

           --with-termlib
                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

           --with-trace
                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.

## FILES

           /usr/share/tabset
                  tab stop initialization database

           /usr/share/terminfo
                  compiled terminal capability database

## NOTES

           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.

## EXTENSIONS

           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
           supported.

           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 term-
               info 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.

## PORTABILITY

           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 nearly all features of its enhanced level.

           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
           applications.

### 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
           unctrl.h.

           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
               unctrl.h.

               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
               term.h.

               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
               prototype.

               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.

## AUTHORS

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

## SEE ALSO

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

    ncurses 6.4                       2024-04-20                       ncurses(3x)