Ncurses Library On

Name

The ncurses library is intended to be base-level conformant with the XSI Curses standard from X/Open. Many extended-level features (in fact, almost all features not directly concerned with wide characters and internationalization) are also supported. The ncurses library routines give the user a terminal-independent method of updating character screens with reasonable optimization. This implementation is “new curses” (ncurses) and is the approved replacement for 4.4BSD classic curses, which has been discontinued. Terminals recognized different sequences to move cursor, change attributes, clear portions of the screen. Curses renders a standard virtual display to look as nearly to the target on these varied monitors when instructed to update. Ncurses is the most widely known implementation of curses, and has motivated further development of other variations, such as BSD curses in the NetBSD project. Although the ncurses library was initially developed under Linux, OpenBSD, FreeBSD, and NetBSD it has been ported to many. A general purpose example of using ncurses in C e.g. For Fedora Linux: If you are using Fedora 22 Linux or the newer versions, you can use the dnf command to install the ncurses library, type: $ sudo dnf install ncurses-devel. Outputs: root@fedora26-osetc # dnf install ncurses-devel Last metadata expiration check: 1:36:24 ago on Fri 21 Jul 2017 09:01:19 AM EDT.

ncurses - CRT screen handling and optimization package

Synopsis

#include <curses.h>

Description

The ncurses library routines give the user a terminal-independent method of updating character screens with reasonable optimization. Thisimplementation is 'new curses' (ncurses) and is the approved replacement for 4.4BSD classic curses, which has been discontinued. This describesncurses version 5.7 (patch 20090207).

The ncurses library emulates the curses(3X) library of System V Release 4 UNIX, and XPG4 (X/Open Portability Guide) curses (also known as XSIcurses). XSI stands for X/Open System Interfaces Extension. The ncurses library is freely redistributable in source form. Differences from the SVr4curses are summarized under the EXTENSIONS and PORTABILITY sections below and described in detail in the respective EXTENSIONS,PORTABILITY and BUGS sections of individual man pages.

The ncurses library also provides many useful extensions, i.e., features which cannot be implemented by a simple add-on library but which requireaccess to the internals of the library.

A program using these routines must be linked with the -lncurses option, or (if it has been generated) with the debugging library -lncurses_g.(Your system integrator may also have installed these libraries under the names -lcurses and -lcurses_g.) The ncurses_g library generates tracelogs (in a file called 'trace' in the current directory) that describe curses actions. See also the section on ALTERNATE CONFIGURATIONS.

The ncurses package supports: overall screen, window and pad manipulation; output to windows and pads; reading terminal input; control over terminaland curses input and output options; environment query routines; color manipulation; use of soft label keys; terminfo capabilities; and access tolow-level terminal-manipulation routines.

The library uses the locale which the calling program has initialized. That is normally done with setlocale:

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 shouldinitialize 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 screensare used. The routine endwin must be called before exiting.

To get character-at-a-time input without echoing (most interactive, screen oriented programs want this), the following sequence should be used:

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

Most programs would additionally use the sequence:

nonl(); 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 bedone by executing the tput init command after the shell environment variable TERM has been exported. tset(1) is usually responsible fordoing this. [See terminfo(5) for further details.]

The ncurses library permits manipulation of data structures, called windows, which can be thought of as two-dimensional arrays of charactersrepresenting 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 createdwith newwin.

Note that curses does not handle overlapping windows, that's done by the panel(3X) library. This means that you can either use stdscror 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 thencurses manual pages. Among those, the most basic routines are move and addch. More general versions of these routines are included withnames 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 is called, telling curses to make the user's CRT screen look like stdscr. Thecharacters in a window are actually of type chtype, (character and attribute data) so that other information about the character may also be stored witheach character.

Special windows called pads may also be manipulated. These are windows which are not constrained to the size of the screen and whose contents neednot be completely displayed. See curs_pad(3X) for more information.

In addition to drawing characters on the screen, video attributes and colors may be supported, causing the characters to show up in such modes asunderlined, 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 drawingcharacters, 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 inthe environment will override information read by terminfo. This would affect a program running in an AT&T 630 layer, for example, where the size ofa 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 thestandard 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 thescreen. 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 redrawinga screen containing garbage. The curscr can be used in only a few routines.

Routine and Argument Names

Many curses routines have two or more versions. The routines prefixed with w require a window argument. The routines prefixed with prequire 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 routinesimply 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 refersto 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 thecoordinates.

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 thedata types used in the library routines, such as WINDOW, SCREEN, bool, and chtype are defined in <curses.h>. Typesused 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 insomething 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 ALTERNATE CONFIGURATIONS). The 'wide' library includes all ofthe 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 torequire 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 thestructure.

Each cell (row and column) in a WINDOW is stored as a cchar_t.

BAUDRATE: The debugging library checks this environment symbol when the application has redirected output to a file. The symbol's numeric value is used for thebaudrate. If no value is found, ncurses uses 9600. This allows testers to construct repeatable test-cases that take into account costs that depend onbaudrate.
COLUMNS: 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 whichthey are executing. If neither the COLUMNS value nor the terminal's screen size is available, ncurses uses the size which may be specified in theterminfo database (i.e., the cols capability).
ESCDELAY: Specifies the total time, in milliseconds, for which ncurses will await a character sequence, e.g., a function key. The default value, 1000 milliseconds, isenough for most uses. However, it is made a variable to accommodate unusual applications.; $HOME/.termcap; $HOME/.terminfo
LINES: Like COLUMNS, specify the height of the screen in characters. See COLUMNS for a detailed description.
MOUSE_BUTTONS_123
NCURSES_ASSUMED_COLORS: Override the compiled-in assumption that the terminal's default colors are white-on-black (see default_colors(3X)). You may set the foreground andbackground color values with this environment variable by proving a 2-element list: foreground,background. For example, to tell ncurses to not assume anythingabout 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 isallowed.
NCURSES_GPM_TERMS: This applies only to ncurses configured to use the GPM interface.
NCURSES_NO_HARD_TABS: Ncurses may use tabs as part of the cursor movement optimization. In some cases, your terminal driver may not handle these properly. Set thisenvironment variable to disable the feature. You can also adjust your stty settings to avoid the problem.
NCURSES_NO_MAGIC_COOKIES: Some terminals use a magic-cookie feature which requires special handling to make highlighting and other video attributes display properly. You can suppressthe highlighting entirely for these terminals by setting this environment variable.
NCURSES_NO_PADDING: Most of the terminal descriptions in the terminfo database are written for real 'hardware' terminals. Many people use terminal emulators which run in awindowing environment and use curses-based applications. Terminal emulators can duplicate all of the important aspects of a hardware terminal, but they do nothave 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, preventingoverruns. The cheapest solution (no hardware cost) is for your program to do this by pausing after operations that the terminal does slowly, such as clearingthe display.
NCURSES_NO_SETBUF: Normally ncurses enables buffered output during terminal initialization. This is done (as in SVr4 curses) for performance reasons. For testingpurposes, both of ncurses and certain applications, this feature is made optional. Setting the NCURSES_NO_SETBUF variable disables output buffering,leaving the output in the original (usually line buffered) mode.
NCURSES_NO_UTF8_ACS: During initialization, the ncurses library checks for special cases where VT100 line-drawing (and the corresponding alternate character setcapabilities) described in the terminfo are known to be missing. Specifically, when running in a UTF-8 locale, the Linux console emulator and the GNU screenprogram ignore these. Ncurses checks the TERM environment variable for these. For other special cases, you should set this environment variable. Doing thistells 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 forterminal 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 andscreen.
NCURSES_TRACE: During initialization, the ncurses debugging library checks the NCURSES_TRACE symbol. If it is defined, to a numeric value, ncurses calls thetrace 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 willwrite the file trace to the current directory.
TERMCAP: If the ncurses library has been configured with termcap support, ncurses will check for a terminal's description in termcap form if itis not available in the terminfo database.; The TERMCAP symbol contains either a terminal description (with newlines stripped out), or a file name telling where the information denoted by the TERMsymbol exists. In either case, setting it directs ncurses to ignore the usual place for this information, e.g., /etc/termcap.
TERMINFO: Overrides the directory in which ncurses searches for your terminal description. This is the simplest, but not the only way to change the list ofdirectories. The complete list of directories in order follows:
TERMINFO_DIRS: Specifies a list of directories to search for terminal descriptions. The list is separated by colons (i.e., ':') on Unix, semicolons on OS/2 EMX. All of theterminal descriptions are in terminfo form, which makes a subdirectory named for the first letter of the terminal names therein.
TERMPATH: If TERMCAP does not hold a file name then ncurses checks the TERMPATH symbol. This is a list of filenames separated by spaces or colons (i.e., ':')on Unix, semicolons on OS/2 EMX. If the TERMPATH symbol 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 orsetgid permissions: $TERMINFO, $TERMINFO_DIRS, $TERMPATH, as well as $HOME.
--disable-overwrite: The standard include for ncurses is as noted in SYNOPSIS:; #include <curses.h>; It also omits a symbolic link which would allow you to use -lcurses to build executables.
--enable-widec: The configure script renames the library and (if the --disable-overwrite option is used) puts the header files in a different subdirectory. All ofthe library names have a 'w' appended to them, i.e., instead of; -lncurses; You must also define _XOPEN_SOURCE_EXTENDED when compiling for the wide-character library to use the extended (wide-character) functions. Thecurses.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 theWINDOW structure differs, and very few applications require more than a pointer to WINDOWs. If the headers are installed allowing overwrite, thewide-character library's headers should be installed last, to allow applications to be built using either library from the same set of headers.
--with-shared
--with-normal
--with-debug
--with-profile: The shared and normal (static) library names differ by their suffixes, e.g., libncurses.so and libncurses.a. The debug and profiling librariesadd a '_g' and a '_p' to the root names respectively, e.g., libncurses_g.a and libncurses_p.a.
--with-trace: The trace function normally resides in the debug library, but it is sometimes useful to configure this in the shared library. Configure scriptsshould check for the function's existence rather than assuming it is always in the debug library.

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Ncurses Library On

Name

Synopsis

Description

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Environment

Alternate Configurations

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Portability

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Authors

Referenced By

Applies to:

No Curses Or Ncurses Library On This System

Goal

Ncurses Library On Ubuntu

Solution

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