- The ncurses library routines give the user a terminal-independent
- method of updating character screens with reasonable optimization.
- This implementation is "new curses" (ncurses) and is the approved
- replacement for 4.4BSD classic curses, which has been discontinued.
- This describes ncurses version 6.4 (patch 20230902).
-
- The ncurses library emulates the curses library of System V Release 4
- UNIX, and XPG4 (X/Open Portability Guide) curses (also known as XSI
- curses). XSI stands for X/Open System Interfaces Extension. The
- ncurses library is freely redistributable in source form. Differences
- from the SVr4 curses are summarized under the EXTENSIONS and
- PORTABILITY sections below and described in detail in the respective
- EXTENSIONS, PORTABILITY and BUGS sections of individual man pages.
-
- The ncurses library also provides many useful extensions, i.e.,
- features which cannot be implemented by a simple add-on library but
- which require access to the internals of the library.
-
- A program using these routines must be linked with the -lncurses
- option, or (if it has been generated) with the debugging library
- -lncurses_g. (Your system integrator may also have installed these
- libraries under the names -lcurses and -lcurses_g.) The ncurses_g
- library generates trace logs (in a file called "trace" in the current
- directory) that describe curses actions. See also the section on
- ALTERNATECONFIGURATIONS.
-
- The ncurses package supports: overall screen, window and pad
- manipulation; output to windows and pads; reading terminal input;
- control over terminal and curses input and output options; environment
- query routines; color manipulation; use of soft label keys; terminfo
- capabilities; and access to low-level terminal-manipulation routines.
+ 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 20240601).
+
+ ncurses permits control of the terminal screen's contents; abstraction
+ and subdivision thereof with windows and pads; acquisition of keyboard
+ and mouse events; control of terminal input and output options;
+ selection of color and rendering attributes (such as bold or
+ underline); the definition and use of softlabel keys; access to the
+ terminfo terminal capability database; a termcap compatibility
+ interface; and an abstraction of the system's API for manipulating the
+ terminal (such as termios(3)).
+
+ ncurses implements the 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.
+
+
+
+ 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 would perform further setup as follows.
+
+ noqiflush();
+ 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
+ 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 within 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 as a
+ rule the library does not 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 volume 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 not
+ constrained to the size of the terminal screen and their contents need
+ not be completely displayed. See curs_pad(3x).
+
+ Many terminals support configuration of character cell foreground and
+ background colors as well as attributes, which cause characters to
+ render in such modes as boldfaced, underlined, or in reverse video.
+ 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 addch(3x).
+
+ curses is implemented using the operating system's terminal driver; key
+ 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 can translate the latter into unique keycodes. See
+ keypad(3x) and getch(3x).
+
+ ncurses provides reimplementations of the SVr4 panel(3x), form(3x), and
+ menu(3x) libraries; they permit overlapping windows and ease
+ construction of user interfaces with curses.
- The library uses the locale which the calling program has initialized.
- That is normally done with setlocale(3):
-
- setlocale(LC_ALL,"");
-
- If the locale is not initialized, the library assumes that characters
- are printable as in ISO-8859-1, to work with certain legacy programs.
- You should initialize the locale and not rely on specific details of
- the library when the locale has not been setup.
-
- The function initscr or newterm must be called to initialize the
- library before any of the other routines that deal with windows and
- screens are used. The routine endwin(3x) must be called before
- exiting.
-
- To get character-at-a-time input without echoing (most interactive,
- screen oriented programs want this), the following sequence should be
- used:
-
- initscr();cbreak();noecho();
-
- Most programs would additionally use the sequence:
-
- intrflush(stdscr,FALSE);
- keypad(stdscr,TRUE);
-
- Before a curses program is run, the tab stops of the terminal should be
- set and its initialization strings, if defined, must be output. This
- can be done by executing the tputinit command after the shell
- environment variable TERM has been exported. tset(1) is usually
- responsible for doing this. [See terminfo(5) for further details.]
-
-
-
- The ncurses library permits manipulation of data structures, called
- windows, which can be thought of as two-dimensional arrays of
- characters representing all or part of a CRT screen. A default window
- called stdscr, which is the size of the terminal screen, is supplied.
- Others may be created with newwin.
-
- Note that curses does not handle overlapping windows, that's done by
- the panel(3x) library. This means that you can either use stdscr or
- divide the screen into tiled windows and not using stdscr at all.
- Mixing the two will result in unpredictable, and undesired, effects.
-
- Windows are referred to by variables declared as WINDOW*. These data
- structures are manipulated with routines described here and elsewhere
- in the ncurses manual pages. Among those, the most basic routines are
- move and addch. More general versions of these routines are included
- with names beginning with w, allowing the user to specify a window.
- The routines not beginning with w affect stdscr.
-
- After using routines to manipulate a window, refresh(3x) is called,
- telling curses to make the user's CRT screen look like stdscr. The
- characters in a window are actually of type chtype, (character and
- attribute data) so that other information about the character may also
- be stored with each character.
-
- Special windows called pads may also be manipulated. These are windows
- which are not constrained to the size of the screen and whose contents
- need not be completely displayed. See curs_pad(3x) for more
- information.
-
- In addition to drawing characters on the screen, video 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. Line drawing characters may be
- specified to be output. On input, curses is also able to translate
- arrow and function keys that transmit escape sequences into single
- values. The video attributes, line drawing characters, and input
- values use names, defined in <curses.h>, such as A_REVERSE, ACS_HLINE,
- and KEY_LEFT.
-
-
-
- If the environment variables LINES and COLUMNS are set, or if the
- program is executing in a window environment, line and column
- information in the environment will override information read by
- terminfo. This would affect a program running in an AT&T 630 layer,
- for example, where the size of a screen is changeable (see
- ENVIRONMENT).
-
- If the environment variable TERMINFO is defined, any program using
- curses checks for a local terminal definition before checking in the
- standard place. For example, if TERM is set to att4424, then the
- compiled terminal definition is found in
-
- /usr/share/terminfo/a/att4424.
-
- (The a is copied from the first letter of att4424 to avoid creation of
- huge directories.) However, if TERMINFO is set to $HOME/myterms,
- curses first checks
-
- $HOME/myterms/a/att4424,
-
- and if that fails, it then checks
-
- /usr/share/terminfo/a/att4424.
-
- This is useful for developing experimental definitions or when write
- permission in /usr/share/terminfo is not available.
-
- The integer variables LINES and COLS are defined in <curses.h> and will
- be filled in by initscr with the size of the screen. The constants
- TRUE and FALSE have the values 1 and 0, respectively.
-
- The curses routines also define the WINDOW* variable curscr which is
- used for certain low-level operations like clearing and redrawing a
- screen containing garbage. The curscr can be used in only a few
- routines.
-
-
-
- Many curses routines have two or more versions. The routines prefixed
- with w require a window argument. The routines prefixed with p require
- a pad argument. Those without a prefix generally use stdscr.
-
- The routines prefixed with mv require a y and x coordinate to move to
- before performing the appropriate action. The mv routines imply a call
- to move before the call to the other routine. The coordinate y always
- refers to the row (of the window), and x always refers to the column.
- The upper left-hand corner is always (0,0), not (1,1).
-
- The routines prefixed with mvw take both a window argument and x and y
- coordinates. The window argument is always specified before the
- coordinates.
-
- In each case, win is the window affected, and pad is the pad affected;
- win and pad are always pointers to type WINDOW.
-
- Option setting routines require a Boolean flag bf with the value TRUE
- or FALSE; bf is always of type bool. Most of the data types used in
- the library routines, such as WINDOW, SCREEN, bool, and chtype are
- defined in <curses.h>. Types used for the terminfo routines such as
- TERMINAL are defined in <term.h>.
-
- This manual page describes functions which may appear in any
- configuration of the library. There are two common configurations of
- the library:
-
- ncurses
- the "normal" library, which handles 8-bit characters. The
- normal (8-bit) library stores characters combined with
- attributes in chtype data.
-
- Attributes alone (no corresponding character) may be stored in
- chtype or the equivalent attr_t data. In either case, the data
- is stored in something like an integer.
-
- Each cell (row and column) in a WINDOW is stored as a chtype.
-
- ncursesw
- the so-called "wide" library, which handles multibyte
- characters (see the section on ALTERNATECONFIGURATIONS). The
- "wide" library includes all of the calls from the "normal"
- library. It adds about one third more calls using data types
- which store multibyte characters:
-
- cchar_t
- corresponds to chtype. However it is a structure, because
- more data is stored than can fit into an integer. The
- characters are large enough to require a full integer
- value - and there may be more than one character per cell.
- The video attributes and color are stored in separate
- fields of the structure.
-
- Each cell (row and column) in a WINDOW is stored as a
- cchar_t.
-
- The setcchar(3x) and getcchar(3x) functions store and
- retrieve the data from a cchar_t structure.
-
- wchar_t
- stores a "wide" character. Like chtype, this may be an
- integer.
-
- wint_t
- stores a wchar_t or WEOF - not the same, though both may
- have the same size.
-
- The "wide" library provides new functions which are analogous
- to functions in the "normal" library. There is a naming
- convention which relates many of the normal/wide variants: a
- "_w" is inserted into the name. For example, waddch becomes
- wadd_wch.
-
-
-
- The following table lists the curses routines provided in the "normal"
- and "wide" libraries and the names of the manual pages on which they
- are described. Routines flagged with "*" are ncurses-specific, not
- described by XPG4 or present in SVr4.
-
- curses Routine Name Manual Page Name
+ 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 shell's TERM variable, then
+ run tset(1) or the "tputinit" 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 type descriptions or
+ when write permission to /usr/share/terminfo is not available.
+
+ See section "ENVIRONMENT" below.
+
+
+
+ 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. We introduce the character types in the next subsection.
+
+ bf a 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
+
+
+
+ This man page primarily surveys 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 and a color pair in a chtype datum, which is often
+ an alias of int. A string of curses characters is similar to
+ a C char string; a chtype string ends with an integral 0, the
+ null curses character.
+
+ Attributes and a color pair selection (with no corresponding
+ character) can be stored in variables of chtype or attr_t
+ type. In either case, they are accessed via 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 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".
+
+ cchar_t corresponds to the non-wide configuration's chtype.
+ It is a structure type because it requires more
+ storage than fits 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). A string
+ of complex characters ends with a cchar_t whose
+ wchar_t member is the null wide character.
+ Attributes and a color pair selection are stored in
+ separate fields of the structure, not combined into
+ an integer 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.
+
+
+
- Routines that return an integer return ERR upon failure and an integer
- value other than ERR upon successful completion, unless otherwise noted
- in the routine descriptions.
-
- As a general rule, routines check for null pointers passed as
- parameters, and handle this as an error.
-
- All macros return the value of the w version, except setscrreg,
- wsetscrreg, getyx, getbegyx, and getmaxyx. The return values of
- setscrreg, wsetscrreg, getyx, getbegyx, and getmaxyx are undefined
- (i.e., these should not be used as the right-hand side of assignment
- statements).
-
- Functions with a "mv" prefix first perform a cursor movement using
- wmove, and return an error if the position is outside the window, or if
- the window pointer is null. Most "mv"-prefixed functions (except
- variadic functions such as mvprintw) are provided both as macros and
- functions.
-
- Routines that return pointers return NULL on error.
+ Unless otherwise noted, functions that return integers return the
+ constants OK on success and ERR on failure; see curs_variables(3x).
+ 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 environment symbols are useful for customizing the
- runtime behavior of the ncurses library. The most important ones have
- been already discussed in detail.
-
-
-
- When set, change occurrences of the command_character (i.e., the cmdch
- capability) of the loaded terminfo entries 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 it if it does not happen to be a
- single character.
-
-
-
- The debugging library checks this environment variable when the
- application has redirected output to a file. The variable's numeric
- value is used for the baudrate. If no value is found, ncurses uses
- 9600. This allows testers to construct repeatable test-cases that take
- into account costs that depend on baudrate.
-
-
-
- Specify 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 neither the COLUMNS value nor
- the terminal's screen size is available, ncurses uses the size which
- may be specified in the terminfo database (i.e., the cols capability).
-
- It is important that your application use a correct size for the
- screen. This is not always possible because your application may be
- running on a host which does not honor NAWS (Negotiations About Window
- Size), or because you are temporarily running as another user.
- However, setting COLUMNS and/or LINES overrides the library's use of
- the screen size obtained from the operating system.
-
- Either COLUMNS or LINES symbols may be specified independently. This
- is mainly useful to circumvent legacy misfeatures of terminal
- descriptions, e.g., xterm which commonly specifies a 65 line screen.
- For best results, lines and cols should not be specified in a terminal
- description for terminals which are run as emulations.
-
- Use the use_env function to disable all use of external environment
- (but not including system calls) to determine the screen size. Use the
- use_tioctl function to update COLUMNS or LINES to match the screen size
- obtained from system calls or the terminal database.
-
-
-
- Specifies the total time, in milliseconds, for which ncurses will await
- a character sequence, e.g., a function key. The default value, 1000
- milliseconds, is enough for most uses. However, it is made a variable
- to accommodate unusual applications.
-
- The most common instance where you may wish to change this value is to
- work with slow hosts, e.g., running on a network. If the host cannot
- read characters rapidly enough, it will have the same effect as if the
- terminal did not send characters rapidly enough. The library will
- still see a timeout.
-
- Note that xterm mouse events are built up from character sequences
- received from the xterm. If your application makes heavy use of
- multiple-clicking, you may wish to lengthen this default value because
- the timeout applies to the composed multi-click event as well as the
- individual clicks.
-
- In addition to the environment variable, this implementation provides a
- global variable with the same name. 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.
-
-
-
- Tells ncurses where your home directory is. That is where it may read
- and write auxiliary terminal descriptions:
-
- $HOME/.termcap
- $HOME/.terminfo
-
-
-
- This applies only to the OS/2 EMX port. It specifies the order of
- buttons on the mouse. OS/2 numbers a 3-button mouse inconsistently
- from other platforms:
-
- 1 = left
- 2 = right
- 3 = middle.
-
- This variable lets you customize the mouse. The variable must be three
- numeric digits 1-3 in any order, e.g., 123 or 321. If it is not
- specified, ncurses uses 132.
-
-
-
- Override the compiled-in assumption that the terminal's default colors
- are white-on-black (see default_colors(3x)). You may set the
- foreground and background color values with this environment variable
- by proving a 2-element list: foreground,background. For example, to
- tell ncurses to not assume anything about the colors, set this to
- "-1,-1". To make it green-on-black, set it to "2,0". Any positive
- value from zero to the terminfo max_colors value is allowed.
-
-
-
- This applies only to the MinGW port of ncurses.
-
- The Console2 program's handling of the Microsoft Console API call
- CreateConsoleScreenBuffer is defective. Applications which use this
- 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.
-
-
-
- This applies only to ncurses configured to use the GPM interface.
-
- If present, the environment variable is a list of one or more terminal
- names against which the TERM environment variable is matched. Setting
- it to an empty value disables the GPM interface; using the built-in
- support for xterm, etc.
-
- If the environment variable is absent, ncurses will attempt to open GPM
- if TERM contains "linux".
-
-
-
- Ncurses may use tabs as part of the cursor movement optimization. In
- some cases, your terminal driver may not handle these properly. Set
- this environment variable to disable the feature. You can also adjust
- your stty(1) settings to avoid the problem.
-
-
-
- Some terminals use a magic-cookie feature which requires special
- handling to make highlighting and other video attributes display
- properly. You can suppress the highlighting entirely for these
- terminals by setting this environment variable.
-
-
-
- Most of the terminal descriptions in the terminfo database are written
- for real "hardware" terminals. Many people use terminal emulators
- which run in a windowing environment and use curses-based applications.
- Terminal emulators can duplicate all of the important aspects of a
- hardware terminal, but they do not have the same limitations. The
- chief limitation of a hardware terminal from the standpoint of your
- application is the management of dataflow, i.e., timing. Unless a
+ 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 developers to construct repeatable test cases that take
+ into account optimization decisions that depend on baud rate.
+
+
+
+ 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 store 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
+ 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.
+ ncurses enforces an upper limit of 512 on each when reading the value.
+ 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
+ escapesequence (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; ncurses enforces an upper limit of 30,000 (30
+ seconds) when reading the value.
+
+ 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.
+
+
+
+ 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 terminfomax_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 type names, delimited by
+ vertical bars (|) or colons (:), 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), it (or your application) must manage dataflow,
- preventing overruns. The cheapest solution (no hardware cost) is for
- your program to do this by pausing after operations that the terminal
- does slowly, such as clearing the display.
-
- As a result, many terminal descriptions (including the vt100) have
- delay times embedded. You may wish to use these descriptions, but not
- want to pay the performance penalty.
-
- Set the NCURSES_NO_PADDING environment variable to disable all but
- mandatory padding. Mandatory padding is used as a part of special
- control sequences such as flash.
-
-
-
- This setting is obsolete. Before changes
-
- o started with 5.9 patch 20120825 and
-
- o continued though 5.9 patch 20130126
-
- ncurses enabled buffered output during terminal initialization. This
- was done (as in SVr4 curses) for performance reasons. For testing
- purposes, both of ncurses and certain applications, this feature was
- made optional. Setting the NCURSES_NO_SETBUF variable disabled output
- buffering, leaving the output in the original (usually line buffered)
- mode.
-
- In the current implementation, ncurses performs its own buffering and
- does not require this workaround. It does not modify the buffering of
- the standard output.
-
- The reason for the change was to make the behavior for interrupts and
- other signals more robust. One drawback is that certain
- nonconventional programs would mix ordinary stdio calls with ncurses
- calls and (usually) work. This is no longer possible since ncurses is
- not using the buffered standard output but its own output (to the same
- file descriptor). As a special case, the low-level calls such as putp
- still use the standard output. But high-level curses calls do not.
-
-
-
- During initialization, the ncurses library checks for special cases
- where VT100 line-drawing (and the corresponding alternate character set
- capabilities) described in the terminfo are known to be missing.
- Specifically, when running in a UTF-8 locale, the Linux console
- emulator and the GNU screen program ignore these. Ncurses checks the
- TERM environment variable for these. For other special cases, you
- should set this environment variable. Doing this tells ncurses to use
- Unicode values which correspond to the VT100 line-drawing glyphs. That
- works for the special cases cited, and is likely to work for terminal
- emulators.
-
- When setting this variable, you should set it to a nonzero value.
- Setting it to zero (or to a nonnumber) disables the special check for
- "linux" and "screen".
-
- As an alternative to the environment variable, ncurses checks for an
- extended terminfo capability U8. This is a numeric capability which
- can be compiled using tic-x. For example
+ does flow control), an application must manage flow 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
+ not.
+
+
+
+ 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.
@@ -1007,167 +1034,137 @@
xterm-utf8|xterm relying on UTF-8 line-graphics,
U8#1, use=xterm,
- The name "U8" is chosen to be two characters, to permit it to be used
- by applications that use ncurses' termcap interface.
-
+ The two-character name "U8" was chosen to permit its use via ncurses's
+ termcap interface.
-
- During initialization, the ncurses debugging library checks the
- NCURSES_TRACE environment variable. If it is defined, to a numeric
- value, ncurses calls the trace function, using that value as the
- argument.
- The argument values, which are defined in curses.h, provide several
- types of information. When running with traces enabled, your
- application will write the file trace to the current directory.
+
+ 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.
- See curs_trace(3x) for more information.
+
+ 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.
-
- Denotes your terminal type. Each terminal type is distinct, though
- many are similar.
+ 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.
- TERM is commonly set by terminal emulators to help applications find a
- workable terminal description. Some of those choose a popular
- approximation, e.g., "ansi", "vt100", "xterm" rather than an exact fit.
- Not infrequently, your application will have problems with that
- approach, e.g., incorrect function-key definitions.
- If you set TERM in your environment, it has no effect on the operation
- of the terminal emulator. It only affects the way applications work
- within the terminal. Likewise, as a general rule (xterm(1) being a
- rare exception), terminal emulators which 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.
-
- If the ncurses library has been configured with termcap support,
- ncurses will check for a terminal's description in termcap form if it
- is not available in the terminfo database.
+
+ ncurses can be configured to read terminal type description databases
+ in various locations using different formats. This variable overrides
+ the default location.
- The TERMCAP environment variable contains either a terminal description
- (with newlines stripped out), or a file name telling where the
- information denoted by the TERM environment variable exists. In either
- case, setting it directs ncurses to ignore the usual place for this
- information, e.g., /etc/termcap.
+ 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/.
-
- ncurses can be configured to read from multiple terminal databases.
- The TERMINFO variable overrides the location for the default terminal
- database. Terminal descriptions (in terminal format) are stored in
- terminal databases:
+ 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 Normally these are stored in a directory tree, using subdirectories
- named by the first letter of the terminal names therein.
+ o If ncurses is configured with termcap support, this variable may
+ contain the location of a termcap file.
- This is the scheme used in System V, which legacy Unix systems use,
- and the TERMINFO variable is used by curses applications on those
- systems to override the default location of the terminal database.
+ 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).
- o If ncurses is built to use hashed databases, then each entry in
- this list may be the path of a hashed database file, e.g.,
+ TERMINFO=$(infocmp -0 -Q2 -q)
+ export TERMINFO
- /usr/share/terminfo.db
+ The compiled description is used only if it corresponds to the
+ terminal type identified by TERM.
- rather than
+ Setting TERMINFO is the simplest, but not the only, way to direct
+ ncurses to a terminal database. The search path is as follows.
- /usr/share/terminfo/
+ o the last terminal database to which the running ncurses application
+ wrote, if any
- 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, reading it directly rather than
- using the terminfo library calls.
+ o the location specified by the TERMINFO environment variable
- o If ncurses is built with a support for reading termcap files
- directly, then an entry in this list may be the path of a termcap
- file.
+ o$HOME/.terminfo
- o If the TERMINFO variable begins with "hex:" or "b64:", ncurses uses
- the remainder of that variable as a compiled terminal description.
- You might produce the base64 format using infocmp(1m):
+ o locations listed in the TERMINFO_DIRS environment variable
- TERMINFO="$(infocmp -0 -Q2 -q)"
- export TERMINFO
+ o location(s) configured and compiled into ncurses
- The compiled description is used if it corresponds to the terminal
- identified by the TERM variable.
+ o/usr/share/terminfo
- Setting TERMINFO is the simplest, but not the only way to set location
- of the default terminal database. The complete list of database
- locations in order follows:
- o the last terminal database to which ncurses wrote, if any, is
- searched first
+
+ 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.
- o the location specified by the TERMINFO environment variable
- o $HOME/.terminfo
+
+ 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.
- o locations listed in the TERMINFO_DIRS environment variable
-
- o one or more locations whose names are configured and compiled
- into the ncurses library, i.e.,
-
- o /usr/share/terminfo (corresponding to the TERMINFO_DIRS
- variable)
-
- o /usr/share/terminfo (corresponding to the TERMINFO variable)
-
-
-
- Specifies a list of locations to search for terminal descriptions.
- Each location in the list is a terminal database as described in the
- section on the TERMINFO variable. The list is separated by colons
- (i.e., ":") on Unix, semicolons on OS/2 EMX.
-
- There is no corresponding feature in System V terminfo; it is an
- extension developed for ncurses.
-
-
-
- If TERMCAP does not hold a file name then ncurses checks the TERMPATH
- environment variable. This is a list of filenames separated by spaces
- or colons (i.e., ":") on Unix, semicolons on OS/2 EMX.
-
- If the TERMPATH environment variable is not set, ncurses looks in the
- files
-
- /etc/termcap, /usr/share/misc/termcap and $HOME/.termcap,
-
- in that order.
-
- The library may be configured to disregard the following variables when
- the current user is the superuser (root), or if the application uses
- setuid or setgid permissions:
-
- $TERMINFO, $TERMINFO_DIRS, $TERMPATH, as well as $HOME.
+ 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.
- Several different configurations are possible, depending on the
- configure script options used when building ncurses. There are a few
- main options whose effects are visible to the applications developer
- using ncurses:
+ 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:
+ --disable-overwrite
+ The standard C preprocessor inclusion for the curses library is as
+ follows.
#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.,
+ This option is used to avoid file name conflicts between ncurses
+ and an existing curses installation on the system. If ncurses is
+ installed disabling overwrite, it puts its header files in a
+ subdirectory. Here is an example.
#include<ncurses/curses.h>
- It also omits a symbolic link which would allow you to use
- -lcurses to build executables.
+ Installation also omits a symbolic link that would cause the
+ compiler's -lcurses option to link object files with ncurses
+ instead of the system curses library.
+
+ The directory used by this configuration of ncurses is shown in
+ section "SYNOPSIS" above.
- --enable-widec
+ --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"
@@ -1182,7 +1179,7 @@
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 XSI Curses, Issue 4:
+ 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
@@ -1200,17 +1197,17 @@
than curses.h may require a specific value for _XOPEN_SOURCE
(or a system-specific symbol).
- The curses.h file which is installed for the wide-character
- library is designed to be compatible with the normal library's
- header. Only the size of the WINDOW structure differs, and very
- few applications require more than a pointer to WINDOWs.
+ 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
+ --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).
@@ -1220,19 +1217,16 @@
to set these values. Some applications (very few) may require
changes to work with this convention.
- --with-shared
-
- --with-normal
-
- --with-debug
-
- --with-profile
+ --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
+ --with-termlib
Low-level functions which do not depend upon whether the library
supports wide-characters, are provided in the tinfo library.
@@ -1242,21 +1236,21 @@
Those functions are described in these pages:
- ocurs_extend(3x) - miscellaneous curses extensions
+ ocurs_extend(3x) - miscellaneous curses extensions
- ocurs_inopts(3x) - curses input options
+ ocurs_inopts(3x) - curses input options
- ocurs_kernel(3x) - low-level curses routines
+ ocurs_kernel(3x) - low-level curses routines
- ocurs_termattrs(3x) - curses environment query routines
+ ocurs_termattrs(3x) - curses environment query routines
- ocurs_termcap(3x) - curses emulation of termcap
+ ocurs_termcap(3x) - curses emulation of termcap
- ocurs_terminfo(3x) - curses interfaces to terminfo database
+ ocurs_terminfo(3x) - curses interface to terminfo database
- ocurs_util(3x) - miscellaneous curses utility routines
+ ocurs_util(3x) - miscellaneous curses utility routines
- --with-trace
+ --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
@@ -1264,216 +1258,221 @@
- terminfo(5) and related pages whose names begin "curs_" for detailed
- routine descriptions.
- curs_variables(3x)
- user_caps(5) for user-defined capabilities
+
+
+ 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 in 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.
- The ncurses library can be compiled with an option (-DUSE_GETCAP) that
- falls back to the old-style /etc/termcap file 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 significant cost in
- core and startup cycles.
-
- The ncurses library includes facilities for capturing mouse events on
- certain terminals (including xterm). See the curs_mouse(3x) manual
- page for details.
-
- The ncurses library includes facilities for responding to window
- resizing events, e.g., when running in an xterm. See the
- resizeterm(3x) and wresize(3x) manual pages for details. In addition,
- the library may be configured with a SIGWINCH handler.
-
- The ncurses library extends the fixed set of function key capabilities
- of terminals by allowing the application designer to define additional
- key sequences at runtime. See the define_key(3x)key_defined(3x), and
- keyok(3x) manual pages for details.
-
- The ncurses library can exploit the capabilities of terminals which
- implement the ISO-6429 SGR 39 and SGR 49 controls, which allow an
- application to reset the terminal to its original foreground and
- background colors. From the users' perspective, the application is
- able to draw colored text on a background whose color is set
- independently, providing better control over color contrasts. See the
- default_colors(3x) manual page for details.
-
- The ncurses library includes a function for directing application
- output to a printer attached to the terminal device. See the
- curs_print(3x) manual page for details.
+ 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).
-
- The ncurses library is intended to be BASE-level conformant with XSI
- Curses. The EXTENDED XSI Curses functionality (including color
- support) is supported.
+ ncurses allows an application to query the terminal for the presence of
+ a wide variety of special keys; see has_key(3x).
- A small number of local differences (that is, individual differences
- between the XSI Curses and ncurses calls) are described in PORTABILITY
- sections of the library man pages.
+ 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).
-
- In many cases, X/Open Curses is vague about error conditions, omitting
- some of the SVr4 documentation.
+ An ncurses application can eschew knowledge of WINDOW structure
+ internals, instead using accessor functions such as is_scrollok(3x).
- Unlike other implementations, this one checks parameters such as
- pointers to WINDOW structures to ensure they are not null. The main
- reason for providing this behavior is 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 were detected.
- Relying on this (or some other) extension will adversely affect the
- portability of curses applications.
+ ncurses enables an application to direct its 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.
-
- Most of the extensions provided by ncurses have not been standardized.
- Some have been incorporated into other implementations, such as
- PDCurses or NetBSD curses. Here are a few to consider:
+ ncurses permits modification of unctrl(3x)'s behavior; see
+ use_legacy_coding(3x).
- o The routine has_key is not part of XPG4, nor is it present in SVr4.
- See the curs_getch(3x) manual page for details.
+ Rudimentary support for multi-threaded applications may be available;
+ see curs_threads(3x).
- o The routine slk_attr is not part of XPG4, nor is it present in
- SVr4. See the curs_slk(3x) manual page for details.
+ Functions that ease the management of multiple screens can be exposed;
+ see curs_sp_funcs(3x).
- o The routines getmouse, mousemask, ungetmouse, mouseinterval, and
- wenclose relating to mouse interfacing are not part of XPG4, nor
- are they present in SVr4. See the curs_mouse(3x) manual page for
- details.
+ 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 routine mcprint was not present in any previous curses
- implementation. See the curs_print(3x) manual page for details.
+ The library facilitates auditing and troubleshooting of its behavior;
+ see curs_trace(3x).
- o The routine wresize is not part of XPG4, nor is it present in SVr4.
- See the wresize(3x) manual page for details.
+ Compiling ncurses with the option -DUSE_GETCAP causes it 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.
- o The WINDOW structure's internal details can be hidden from
- application programs. See curs_opaque(3x) for the discussion of
- is_scrollok, etc.
+ PDCurses and NetBSD curses incorporate some ncurses extensions.
+ Individual man pages indicate where this is the case.
- o This implementation can be configured to provide rudimentary
- support for multi-threaded applications. See curs_threads(3x) for
- details.
- o This implementation can also be configured to provide a set of
- functions which improve the ability to manage multiple screens.
- See curs_sp_funcs(3x) for details.
+
+ 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.
-
- In historic curses versions, delays embedded in the capabilities cr,
- ind, cub1, ff and tab activated corresponding delay bits in the UNIX
- tty driver. In this implementation, all padding is done by sending NUL
- bytes. This method is slightly more expensive, but narrows the
- interface to the UNIX kernel significantly and increases the package's
- portability correspondingly.
+
- The header file <curses.h> automatically includes the header files
- <stdio.h> and <unctrl.h>.
+ 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. An application that relies
+ on ncurses to check its function parameters for validity limits its
+ portability and robustness.
- X/Open Curses has more to say, but does not finish the story:
- The inclusion of <curses.h> may make visible all symbols from the
- headers <stdio.h>, <term.h>, <termios.h>, and <wchar.h>.
+
+ 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.
- Here is a more complete story:
- o Starting with BSD curses, all implementations have included
- <stdio.h>.
+
+ The header file curses.h itself includes the header files stdio.h and
+ unctrl.h.
- BSD curses included <curses.h> and <unctrl.h> from an internal
- header "curses.ext" ("ext" was a short name for externs).
+ X/Open Curses has more to say,
- BSD curses used <stdio.h> internally (for printw and scanw), but
- nothing in <curses.h> itself relied upon <stdio.h>.
+ The inclusion of curses.h may make visible all symbols from the
+ headers stdio.h, term.h, termios.h, and wchar.h.
- o SVr2 curses added newterm(3x), which relies upon <stdio.h>. That
- is, the function prototype uses FILE.
+ but does not finish the story. A more complete account follows.
- SVr4 curses added putwin and getwin, which also use <stdio.h>.
+ o The first curses, in 4BSD, provided a curses.h file.
- X/Open Curses documents all three of these functions.
+ BSD curses code included curses.h and unctrl.h from an internal
+ header file curses.ext, where "ext" abbreviated "externs".
- SVr4 curses and X/Open Curses do not require the developer to
- include <stdio.h> before including <curses.h>. Both document
- curses showing <curses.h> as the only required header.
+ 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.
- As a result, standard <curses.h> will always include <stdio.h>.
+ o SVr2 curses added newterm, which relies upon stdio.h because its
+ function prototype employs the FILE type.
- o X/Open Curses is inconsistent with respect to SVr4 regarding
- <unctrl.h>.
+ SVr4 curses added putwin and getwin, which also use stdio.h.
- As noted in curs_util(3x), ncurses includes <unctrl.h> from
- <curses.h> (like SVr4).
+ X/Open Curses specifies all three of these functions.
- o X/Open's comments about <term.h> and <termios.h> may refer to HP-UX
- and AIX:
+ 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.
- HP-UX curses includes <term.h> from <curses.h> to declare setupterm
- in curses.h, but ncurses (and Solaris curses) do not.
+ As a result, standard curses.h always includes stdio.h.
- AIX curses includes <term.h> and <termios.h>. Again, ncurses (and
- Solaris curses) do not.
+ o X/Open Curses and SVr4 curses are inconsistent with respect to
+ unctrl.h.
- o X/Open says that <curses.h> may include <term.h>, but there is no
- requirement that it do that.
+ As noted in curs_util(3x), ncurses includes unctrl.h from curses.h
+ (as SVr4 does).
- Some programs use functions declared in both <curses.h> and
- <term.h>, and must include both headers in the same module. Very
- old versions of AIX curses required including <curses.h> before
- including <term.h>.
+ o X/Open Curses's comments about term.h and termios.h may refer to
+ HP-UX and AIX.
- Because ncurses header files include the headers needed to define
- datatypes used in the headers, ncurses header files can be included
- in any order. But for portability, you should include <curses.h>
- before <term.h>.
+ HP-UX curses includes term.h from curses.h to declare setupterm in
+ curses.h, but ncurses and Solaris curses do not.
- o X/Open Curses says "maymakevisible" because including a header
- file does not necessarily make all symbols in it visible (there are
- ifdef's to consider).
+ AIX curses includes term.h and termios.h. Again, ncurses and
+ Solaris curses do not.
- For instance, in ncurses <wchar.h> may be included if the proper
- symbol is defined, and if ncurses is configured for wide-character
- support. If the header is included, its symbols may be made
- visible. That depends on the value used for _XOPEN_SOURCE feature
- test macro.
+ o X/Open Curses says that curses.hmay include term.h, but does not
+ require it to do so.
- o X/Open Curses documents one required header, in a special case:
- <stdarg.h> before <curses.h> to prototype the vw_printw and
- vw_scanw functions (as well as the obsolete the vwprintw and
- vwscanw functions). Each of those uses a va_list parameter.
+ 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 two obsolete functions were introduced in SVr3. The other
- functions were introduced in X/Open Curses. In between, SVr4
- curses provided for the possibility that an application might
- include either <varargs.h> or <stdarg.h>. Initially, that was done
- by using void* for the va_list parameter. Later, a special type
- (defined in <stdio.h>) was introduced, to allow for compiler type-
- checking. That special type is always available, because <stdio.h>
- is always included by <curses.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.
- None of the X/Open Curses implementations require an application to
- include <stdarg.h> before <curses.h> because they either have
- allowed for a special type, or (like ncurses) include <stdarg.h>
- directly to provide a portable interface.
+ 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.hmay 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.
-
- If standard output from a ncurses program is re-directed to something
- which is not a tty, screen updates will be directed to standard error.
- This was an undocumented feature of AT&T System V Release 3 curses.
+ 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.