X-Git-Url: http://ncurses.scripts.mit.edu/?a=blobdiff_plain;f=doc%2Fhtml%2Fman%2Fncurses.3x.html;fp=doc%2Fhtml%2Fman%2Fncurses.3x.html;h=fcd1725b9e99806de11296e630c91967bcc09ea6;hb=75a9c36c205ebefe07580acd0b1053a2abbd44b9;hp=330628ed92e770b9db38586389582d53aebea157;hpb=382c1d0c3c8959d2e5ffb69e86469d00937aa4ae;p=ncurses.git
diff --git a/doc/html/man/ncurses.3x.html b/doc/html/man/ncurses.3x.html
index 330628ed..fcd1725b 100644
--- a/doc/html/man/ncurses.3x.html
+++ b/doc/html/man/ncurses.3x.html
@@ -28,19 +28,19 @@
* sale, use or other dealings in this Software without prior written *
* authorization. *
****************************************************************************
- * @Id: ncurses.3x,v 1.204 2024/03/23 20:42:29 tom Exp @
+ * @Id: ncurses.3x,v 1.207 2024/04/14 00:34:00 tom Exp @
-->
-ncurses 3x 2024-03-23 ncurses 6.4 Library calls
+ncurses 3x 2024-04-13 ncurses 6.4 Library calls
-
ncurses 3x 2024-03-23 ncurses 6.4 Library calls
+
ncurses 3x 2024-04-13 ncurses 6.4 Library calls
ncurses(3x) Library calls ncurses(3x)
@@ -61,158 +61,152 @@
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
- describes ncurses version 6.4 (patch 20240323).
+ describes ncurses version 6.4 (patch 20240413).
ncurses permits control of the terminal screen's contents; abstraction
and subdivision thereof with windows and pads; the reading of terminal
input; control of terminal input and output options; environment query
routines; color manipulation; the definition and use of softlabel
- keys; terminfo capabilities; a termcap compatibility interface; and
- access to low-level terminal-manipulation routines.
+ keys; terminfo capability access; a termcap compatibility interface;
+ and an abstraction of the system's API for manipulating the terminal
+ (such as termios(3)).
- ncurses implements the standard interface described by X/Open Curses
- Issue 7. In many behavioral details not standardized by X/Open,
- ncurses emulates the curses library of SVr4 and provides numerous
+ ncurses implements the standard interface described by X/Open Curses
+ Issue 7. In many behavioral details not standardized by X/Open,
+ ncurses emulates the curses library of SVr4 and provides numerous
useful extensions.
- ncurses man pages employ several sections to clarify matters of usage
+ ncurses man pages employ several sections to clarify matters of usage
and interoperability with other curses implementations.
- 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 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
+ 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
+ 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 for
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 section "ALTERNATE
- CONFIGURATIONS" below.
+ 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,"");
+ 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 set up.
+ 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.
- 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.
+ 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), the following sequence should be
- used:
+ To get character-at-a-time input without echoing--most interactive,
+ screen-oriented programs want this--use the following sequence.
- initscr();cbreak();noecho();
+ initscr(); cbreak(); noecho();
- Most programs would additionally use the sequence:
+ Most applications perform further setup as follows.
- intrflush(stdscr,FALSE);
- keypad(stdscr,TRUE);
+ 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. (The BSD-style tset(1)
- utility also performs this function.) See subsection "Tabs and
- Initialization" of terminfo(5).
+ 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),
+ 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
+ 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.
+ 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.
+ 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.
+ cursor and write a character to stdscr, respectively.
+
+ Frequent changes to the terminal screen can cause unpleasant flicker or
+ inefficient use of the communication channel to the device, so the
+ library does not generally update it automatically. Therefore, after
+ using curses functions to accumulate a set of desired updates that make
+ sense to present together, call refresh(3x) to tell the library to make
+ the user's screen look like stdscr. The library optimizes its output
+ by computing a minimal number of operations to mutate the screen from
+ its state at the previous refresh to the new one. Effective
+ optimization demands accurate information about the terminal device:
+ the management of such information is the province of the terminfo(3x)
+ API, a feature of every standard curses implementation.
Special windows called pads may also be manipulated. These are windows
- that are not constrained to the size of the terminal screen and whose
+ that are not constrained to the size of the terminal screen and whose
contents need not be completely displayed. See curs_pad(3x).
- In addition to drawing characters on the screen, rendering attributes
- and colors may be supported, causing the characters to show up in such
- modes as underlined, in reverse video, or in color on terminals that
+ In addition to drawing characters on the screen, rendering attributes
+ and colors may be supported, causing the characters to show up in such
+ modes as underlined, in reverse video, or in color on terminals that
support such display enhancements. See curs_attr(3x).
- curses predefines constants for a small set of 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 predefines constants for a small set of forms-drawing graphics
+ corresponding to the DEC Alternate Character Set (ACS), a feature of
+ VT100 and other terminals. See waddch(3x).
- curses is implemented using the operating system's terminal driver;
- keystroke events are received not as scan codes but as byte sequences.
- Graphical keycaps (alphanumeric and punctuation keys, and the space)
+ 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
+ keypad, arrow, and function keys, appears as a control character or a
+ multibyte escapesequence.curses translates these into unique keycodes. See getch(3x).
+ ncurses provides reimplementations of the SVr4 panel(3x), form(3x), and
+ menu(3x) libraries to ease construction of user interfaces with curses.
+
-
The selection of an appropriate value of TERM in the process
environment is essential to correct curses and terminfo library
operation. A well-configured system selects a correct TERM value
automatically; tset(1) may assist with troubleshooting exotic
situations.
+ If you change the terminal type, export the TERM environment variable
+ in the shell, 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
@@ -228,17 +222,21 @@
- 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.
+ 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.
- bfbool (TRUE or FALSE)
- win pointer to WINDOW
- pad pointer to WINDOW that is a pad
+ bfbool (TRUE or FALSE)
+ win pointer to a WINDOW
+ pad pointer to a WINDOW that is a pad
@@ -264,63 +262,65 @@
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
+ data than fit into a standard scalar type. A
+ character code may not be representable as a char,
+ and moreover more than one character may occupy a
+ cell (as with accent marks and other diacritics).
+ Each character is of type wchar_t; a complex
+ character contains one spacing character and zero or
+ more non-spacing characters (see below). Attributes
+ and color data are stored in separate fields of the
structure, not combined as in chtype.
Each cell of a WINDOW is stored as a cchar_t.
- 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
+ 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
+ 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
+ The wide library provides additional functions that
+ complement those in the non-wide library where the size of
+ the underlying character type is significant. A somewhat
+ regular naming convention relates many of the wide variants
+ to their non-wide counterparts; where a non-wide function
+ name contains "ch" or "str", prefix it with "_w" to obtain
+ the wide counterpart. For example, waddch becomes wadd_wch.
+ (Exceptions that add only "w" comprise addwstr, inwstr, and
+ their variants.)
+
+ This convention is inapplicable to some non-wide function
names, so other transformations are used for the wide
- configuration: in the window background management functions,
- "bkgd" becomes "bkgrnd"; the window border-drawing and
- -clearing functions are suffixed with "_set".
+ 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".
Unless otherwise noted, functions that return an integer return OK on
success and ERR on failure. Functions that return pointers return NULL
on failure. Typically, ncurses treats a null pointer passed as a
- function parameter as a failure.
-
- Functions 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.
+ function parameter as a failure. Functions with a "mv" prefix first
+ perform cursor movement using wmove(3x) and fail if the position is
+ outside the window.
- 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.
+ The following symbols from the process environment customize the
+ runtime behavior of ncurses applications. The library may be
+ configured to disregard the variables TERMINFO, TERMINFO_DIRS,
+ TERMPATH, and HOME, if the user is the superuser (root), or the
+ application uses setuid(2) or setgid(2).
+
+
+
+ The debugging library checks this variable when the application has
+ redirected output to a file. Its integral value is used for the baud
+ rate. If that value is absent or invalid, ncurses uses 9600. This
+ feature allows testers to construct repeatable test cases that take
+ into account optimization decisions that depend on baud rate.
- When set, change the command_character (cmdch) capability value of
- loaded terminfo entries to the value of this variable. Very few term-
+ When set, the command_character (cmdch) capability value of loaded
+ terminfo entries changes to the value of this variable. Very few term-info entries provide this feature.
Because this name is also used in development environments to represent
- the C compiler's name, ncurses ignores 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 baud rate. If no value is found, ncurses uses
- 9600. This allows testers to construct repeatable test-cases that take
- into account costs that depend on baud rate.
+ the C compiler's name, ncurses ignores its value if it is not one
+ character in length.
- 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.
+ This variable specifies the width of the screen in characters.
+ Applications running in a windowing environment usually are able to
+ obtain the width of the window in which they are executing. If COLUMNS
+ is not defined and the terminal's screen size is not available from the
+ terminal driver, ncurses uses the size specified by the columns (cols)
+ capability of the terminal type's entry in the terminfo database, if
+ any.
+
+ It is important that your application use the correct screen size.
+ Automatic detection thereof is not always possible because an
+ application may be running on a host that does not honor NAWS
+ (Negotiations About Window Size) or as a different user ID than the
+ owner of the terminal device file. Setting COLUMNS and/or LINES
+ overrides the library's use of the screen size obtained from the
+ operating system.
+
+ The COLUMNS and LINES variables may be specified independently. This
+ property is useful to circumvent misfeatures of legacy terminal type
+ descriptions; xterm(1) descriptions specifying 65 lines were once
+ notorious. For best results, avoid specifying cols and lines
+ capability codes in terminfo descriptions of terminal emulators.
+
+ use_env(3x) can disable use of the process environment in determining
+ the screen size. use_tioctl(3x) can update COLUMNS and LINES to match
+ the screen size obtained from system calls or the terminal database.
- 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.
+ 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.
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.
+ 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.
- 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.
+ 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.
- 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.
+ 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.
-
- Tells ncurses where your home directory is. That is where it may read
- and write auxiliary terminal descriptions:
- $HOME/.termcap
- $HOME/.terminfo
+
- Like COLUMNS, specify the height of the screen in characters. See
- COLUMNS for a detailed description.
+ 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.
- 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.
+ (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".
- 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.
+ 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.
-
- 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.
+
+ (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.
- 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".
+ (Linux only) When ncurses is configured to use the GPM interface, this
+ variable may list one or more terminal names against which the TERM
+ variable (see below) is matched. An empty value disables the GPM
+ interface, using ncurses's built-in support for xterm(1) mouse
+ protocols instead. If the variable is absent, ncurses attempts to open
+ GPM if TERM contains "linux".
- ncurses may use 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.
+ 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.
- 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 to any value.
+ 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 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
+ 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.
+ does flow control), an application must manage flow control itself to
+ prevent overruns and data loss.
- 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.
+ A solution that comes at no hardware cost is for an application to
+ pause after directing a terminal to execute an operation that it
+ performs slowly, such as clearing the display. Many terminal type
+ descriptions, including that for the VT100, embed delay specifications
+ in capabilities. You may wish to use these temrinal descriptions
+ without paying the performance penalty. Set NCURSES_NO_PADDING to any
+ value to disable all but mandatory padding. Mandatory padding is used
+ by such terminal capabilities as flash_screen (flash).
- 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(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.
+ (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.
- 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. 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
- can be compiled using tic-x. For example
+ 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.
@@ -1028,67 +1024,60 @@
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.
-
- See curs_trace(3x) for more information.
+ 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.
- 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
@@ -1097,30 +1086,30 @@
/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.
+ 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
@@ -1129,48 +1118,42 @@
o locations listed in the TERMINFO_DIRS environment variable
- o one or more locations whose names are configured and compiled
+ 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
+ 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,
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.
-
- 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
+ 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
@@ -1178,20 +1161,20 @@
#include<curses.h>
- This option is used to avoid filename conflicts when ncurses is
+ 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
+ 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
@@ -1200,45 +1183,45 @@
-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 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
+ 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
@@ -1248,17 +1231,17 @@
--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:
@@ -1278,8 +1261,8 @@
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.
@@ -1293,71 +1276,78 @@
- X/Open Curses permits most functions it specifies to be made available
+ 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
+ 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
+ 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
+ See subsection "Header files" below regarding symbols exposed by
inclusion of curses.h.
- ncurses enables an application to capture mouse events on certain
+ ncurses enables an application to capture mouse events on certain
terminals, including xterm; 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
+ ncurses provides a means of responding to window resizing events, as
+ when running in a GUI terminal emulator application such as xterm; see
resizeterm(3x) and wresize(3x).
ncurses allows an application to query the terminal for the presence of
a wide variety of special keys; see has_key(3x).
ncurses extends the fixed set of function key capabilities specified by
- X/Open Curses by allowing the application programmer to define
- additional key sequences at runtime; see define_key(3x),
+ 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).
- 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,
+ 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
+ An ncurses application can choose to hide the internal details of
+ WINDOW structures, instead using accessor functions such as
is_scrollok(3x).
- ncurses enables an application to direct application output to a
+ ncurses enables an application to direct application output to a
printer attached to the terminal device; see curs_print(3x).
- ncurses offers slk_attr(3x) as a counterpart of attr_get(3x) for soft-
- label key lines, and extended_slk_color(3x) as a form of slk_color(3x)
- that can gather color information from them when many colors are
+ 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.
+ Some extensions are only available if ncurses is compiled to support
+ them; section "ALTERNATE CONFIGURATIONS" describes how.
- o Rudimentary support for multi-threaded applications may be
+ o Rudimentary support for multi-threaded applications may be
available; see curs_threads(3x).
- o Functions that ease the management of multiple screens can be
+ o Functions that ease the management of multiple screens can be
exposed; see curs_sp_funcs(3x).
+ o To aid applications to debug their memory usage, ncurses optionally
+ offers functions to more aggressively free memory it dynamically
+ allocates itself; see curs_memleaks(3x).
+
+ o The library facilitates auditing and troubleshooting of its
+ behavior; see curs_trace(3x).
+
o The compiler option -DUSE_GETCAP causes the library to fall back to
reading /etc/termcap if the terminal setup code cannot find a term-info entry corresponding to TERM. Use of this feature is not
@@ -1502,7 +1492,7 @@
-ncurses 6.4 2024-03-23 ncurses(3x)
+ncurses 6.4 2024-04-13 ncurses(3x)