- The ncurses library routines give the user a terminal-independent
+ 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
+ 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 20231202).
+ This describes ncurses version 6.4 (patch 20240217).
- The ncurses library emulates the curses library of System V Release 4
+ The ncurses library emulates the curses library of System V Release 4
Unix ("SVr4"), 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.
+ The ncurses library is freely redistributable in source form.
ncurses man pages employ several sections to clarify matters of usage
and interoperability with other curses implementations.
@@ -73,58 +73,59 @@
o "NOTES" describes matters 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 for a function (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
+ 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 to
+ that should be considered when writing to a curses standard, or to
multiple implementations.
- o "HISTORY" examines points of detail in ncurses and other curses
+ 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 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
+ 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 section "ALTERNATE
+ CONFIGURATIONS" below.
+
+ 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 library uses the locale which the calling program has initialized.
+ 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
+ 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
+ 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
+ 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();
@@ -135,177 +136,188 @@
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. (The BSD-style tset(1)
+ 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. (The BSD-style tset(1)
utility also performs this function.) See subsection "Tabs and
Initialization" of terminfo(5).
-
- 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.
+
+ 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. (See panel(3x)
+ if you desire this.) 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. As a rule,
+ window-addressing functions feature names prefixed (or infixed, see
+ below) with "w"; these allow the user to specify a pointer to a WINDOW.
+ Counterparts not thus prefixed (or infixed) affect stdscr. Because
+ moving the cursor prior to another operation is so common, curses
+ generally also provides functions with a "mv" prefix as a convenience.
+ Thus, the library defines all of addch, waddch, mvaddch, and mvwaddch.
+ When both prefixes are present, the order of arguments is a WINDOW
+ pointer first, then a y and x coordinate pair.
+
+ Updating the terminal screen with every curses call can cause
+ unpleasant flicker or inefficient use of the communications channel to
+ the device. 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. ncursesoptimizes 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
- 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.
+ 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, video attributes and
- colors may be supported, causing the characters to show up in such
+ 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. 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
+ support such display enhancements. See curs_attr(3x).
+
+ curses predefines constants for a small set of line-drawing and other
+ graphics corresponding to the DEC Alternate Character Set (ACS), a
+ feature of VT100 and other terminals. See waddch(3x) and wadd_wch(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 escapesequence.curses translates these into unique key
+ codes. See getch(3x).
+
+
+
+ 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 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.
+
+
+
+ Many curses functions have two or more versions. Those prefixed with
+ "w" require a window argument. Four functions prefixed with "p"
+ require a pad argument. Those without a prefix generally operate on
+ stdscr.
+
+ In function synopses, ncurses man pages apply the following names to
+ parameters.
+
+ bfbool (TRUE or FALSE)
+ win pointer to WINDOW
+ pad pointer to WINDOW that is a pad
+
+
+
+ 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 fits into an integral 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.
+
+ The setcchar(3x) and getcchar(3x) functions store and
+ retrieve the data from a cchar_t structure. 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.
+
+ This convention is inapplicable to some non-wide function
+ names, so other transformations are used for the wide
+ configuration: in the window background management functions,
+ "bkgd" becomes "bkgrnd"; the window border-drawing and
+ -clearing functions are suffixed with "_set".
+
+
+
- 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.
+ 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.
- 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.
+ Functions with a "mv" prefix first perform cursor movement using wmove
+ and fail if the position is outside the window, or (for "mvw"
+ functions) if the WINDOW pointer is null.
- The following environment symbols are useful for customizing the
- runtime behavior of the ncurses library. The most important ones have
+ 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.
+
+ When set, change the command_character (cmdch) capability value of
+ loaded terminfo entries 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 it if it does not happen to be a
+ 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
+ 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
+ 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
+ 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
+ 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
+ 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
+ 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
+ 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
+ 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
+ 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
+ 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
+ Tells ncurses where your home directory is. That is where it may read
and write auxiliary terminal descriptions:
$HOME/.termcap
@@ -882,13 +881,13 @@
- Like COLUMNS, specify the height of the screen in characters. See
+ Like COLUMNS, specify the height of the screen in characters. See
COLUMNS for a detailed description.
- 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
+ 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
@@ -896,77 +895,77 @@
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.
+ 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
+ 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.
+ 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
+ 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
+ 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.
+ 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
+ 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 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.
+ ncurses may use tabs as part of cursor movement optimization. In some
+ cases, your terminal driver may not handle these properly. Set this
+ environment variable to any value 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
+ 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.
+ terminals by setting this environment variable to any value.
- Most of the terminal descriptions in the terminfo database are written
- for real "hardware" terminals. Many people use terminal emulators
+ 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
- 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
+ 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
+ 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
+ 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
+ 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.
@@ -977,44 +976,44 @@
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)
+ 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
+ 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
+ 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(3) 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
+ 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
+ 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. ncurseschecksthe
+ TERMenvironmentvariableforthese.Forotherspecialcases,you
+ shouldsetthisenvironmentvariable.Doingthistellsncursestouse
+ UnicodevalueswhichcorrespondtotheVT100line-drawingglyphs.That
+ worksforthespecialcasescited,andislikelytoworkforterminal
+ 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
+ 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
# linux console, if patched to provide working
@@ -1026,67 +1025,67 @@
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 name "U8" is chosen to be two characters, to permit it to be used
+ by applications that use ncurses' 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
+ 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
+ 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.
See curs_trace(3x) for more information.
- Denotes your terminal type. Each terminal type is distinct, though
+ Denotes your terminal type. Each terminal type is distinct, though
many are similar.
- TERM is commonly set by terminal emulators to help applications find a
- workable terminal description. Some of those choose a popular
+ 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
+ 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 the ncurses library has been configured with termcap support,
- ncurses will check for a terminal's description in termcap form if it
+ 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.
The TERMCAP environment variable contains either a terminal description
- (with newlines stripped out), or a file name telling where the
+ (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
+ case, setting it directs ncurses to ignore the usual place for this
information, e.g., /etc/termcap.
- 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
+ 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:
o Normally these are stored in a directory tree, using subdirectories
named by the first letter of the terminal names therein.
This is the scheme used in System V, which legacy Unix systems use,
- and the TERMINFO variable is used by curses applications on those
+ and the TERMINFO variable is used by curses applications on those
systems to override the default location of the terminal database.
- o If ncurses is built to use hashed databases, then each entry in
+ 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.,
/usr/share/terminfo.db
@@ -1095,30 +1094,30 @@
/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, reading it directly rather than
+ The hashed database uses less disk-space and is a little faster
+ than the directory tree. However, some applications assume the
+ existence of the directory tree, reading it directly rather than
using the terminfo library calls.
- 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
+ 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 If the TERMINFO variable begins with "hex:" or "b64:", ncurses uses
- the remainder of that variable as a compiled terminal description.
+ 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):
TERMINFO="$(infocmp -0 -Q2 -q)"
export TERMINFO
- The compiled description is used if it corresponds to the terminal
+ The compiled description is used if it corresponds to the terminal
identified by the TERM variable.
- Setting TERMINFO is the simplest, but not the only way to set location
- of the default terminal database. The complete list of database
+ 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
+ o the last terminal database to which ncurses wrote, if any, is
searched first
o the location specified by the TERMINFO environment variable
@@ -1127,31 +1126,31 @@
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 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
+ 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
+ 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.
+ 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
+ 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
+ If the TERMPATH environment variable is not set, ncurses looks in the
files
/etc/termcap, /usr/share/misc/termcap and $HOME/.termcap,
@@ -1159,37 +1158,37 @@
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
+ the current user is the superuser (root), or if the application uses
setuid or setgid permissions:
$TERMINFO, $TERMINFO_DIRS, $TERMPATH, as well as $HOME.
- 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:
+ 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
+ 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
+ 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"
+ 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
@@ -1198,45 +1197,45 @@
-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
+ 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:
- o Originally, the wide-character feature required the symbol
+ 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
+ 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,
+ 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
+ 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 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
+ 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
+ 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
+ to set these values. Some applications (very few) may require
changes to work with this convention.
--with-shared
@@ -1246,38 +1245,38 @@
--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
+ 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
+ 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
+ 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:
- 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
- The trace function normally resides in the debug library, but it
- is sometimes useful to configure this in the shared library.
+ 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.
@@ -1291,204 +1290,202 @@
- 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.
+ 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.
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.
+ ncurses enables an application to capture mouse events on certain
+ terminals, including xterm; see curs_mouse(3x).
- 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 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).
-
- The ncurses library is intended to be BASE-level conformant with XSI
- Curses. The EXTENDED XSI Curses functionality (including color
- support) is supported.
+ ncurses extends the fixed set of function key capabilities specified by
+ X/Open Curses by allowing the application programmer to define
+ additional key sequences at runtime; see define_key(3x),
+ key_defined(3x), and keyok(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 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 choose to hide the internal details of
+ WINDOW structures, instead using accessor functions such as
+ is_scrollok(3x).
-
- In many cases, X/Open Curses is vague about error conditions, omitting
- some of the SVr4 documentation.
+ ncurses enables an application to direct application output to a
+ printer attached to the terminal device; see curs_print(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 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 only available if ncurses is compiled to support
+ them; see section "ALTERNATE CONFIGURATIONS" above.
-
- 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:
+ o Rudimentary support for multi-threaded applications may be
+ available; see curs_threads(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.
+ o Functions that ease the management of multiple screens can be
+ exposed; see curs_sp_funcs(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.
+ 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.
- 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.
+ PDCurses and NetBSD curses incorporate some ncurses extensions.
+ Individual man pages indicate where this is the case.
- o The routine mcprint was not present in any previous curses
- implementation. See the curs_print(3x) manual page for details.
- o The routine wresize is not part of XPG4, nor is it present in SVr4.
- See the wresize(3x) manual page 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 nearly all its enhanced features.
+
+ Differences between X/Open Curses and ncurses are documented in the
+ "PORTABILITY" sections of applicable man pages.
- o The WINDOW structure's internal details can be hidden from
- application programs. See curs_opaque(3x) for the discussion of
- is_scrollok, etc.
- o This implementation can be configured to provide rudimentary
- support for multi-threaded applications. See curs_threads(3x) for
- details.
+
+ In many cases, X/Open Curses is vague about error conditions, omitting
+ some of the SVr4 documentation.
- 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.
+ 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.
-
+ 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
+ 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 itself includes the header files stdio.h and
unctrl.h.
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
+ The inclusion of <curses.h> may make visible all symbols from the
headers <stdio.h>, <term.h>, <termios.h>, and <wchar.h>.
Here is a more complete story:
- o Starting with BSD curses, all implementations have included
+ o Starting with BSD curses, all implementations have included
<stdio.h>.
- BSD curses included <curses.h> and <unctrl.h> from an internal
- header "curses.ext" ("ext" was a short name for externs).
+ BSD curses included <curses.h> and <unctrl.h> from an internal
+ header file curses.ext ("ext" abbreviated "externs").
- BSD curses used <stdio.h> internally (for printw and scanw), but
+ BSD curses used <stdio.h> internally (for printw and scanw), but
nothing in <curses.h> itself relied upon <stdio.h>.
- o SVr2 curses added newterm(3x), which relies upon <stdio.h>. That
+ o SVr2 curses added newterm(3x), which relies upon <stdio.h>. That
is, the function prototype uses FILE.
SVr4 curses added putwin and getwin, which also use <stdio.h>.
X/Open Curses documents all three of these functions.
- SVr4 curses and X/Open Curses do not require the developer to
+ 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.
As a result, standard <curses.h> will always include <stdio.h>.
- o X/Open Curses is inconsistent with respect to SVr4 regarding
+ o X/Open Curses is inconsistent with respect to SVr4 regarding
<unctrl.h>.
- As noted in curs_util(3x), ncurses includes <unctrl.h> from
+ As noted in curs_util(3x), ncurses includes <unctrl.h> from
<curses.h> (like SVr4).
o X/Open'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.
+ in curses.h, but ncurses (and Solaris curses) do not.
- AIX curses includes <term.h> and <termios.h>. Again, ncurses (and
+ AIX curses includes <term.h> and <termios.h>. Again, ncurses (and
Solaris curses) do not.
- o X/Open says that <curses.h> may include <term.h>, but there is no
+ o X/Open says that <curses.h> may include <term.h>, but there is no
requirement that it do that.
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
+ <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>.
- 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>
+ 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>.
- o X/Open Curses says "maymakevisible" because including a header
+ 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).
- 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
+ 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 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
+ 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.
- 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
+ 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-
+ 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>.
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>
+ 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.
@@ -1502,7 +1499,7 @@
-ncurses 6.4 2023-12-02 ncurses(3x)
+ncurses 6.4 2024-01-13 ncurses(3x)