Announcing ncurses 5.1
The ncurses (new curses) library is a free software emulation of curses in System V Release 4.0, and more. It uses terminfo format, supports pads and color and multiple highlights and forms characters and function-key mapping, and has all the other SYSV-curses enhancements over BSD curses.
In mid-June 1995, the maintainer of 4.4BSD curses declared that he considered 4.4BSD curses obsolete, and is encouraging the keepers of Unix releases such as BSD/OS, freeBSD and netBSD to switch over to ncurses.
The ncurses code was developed under GNU/Linux. It should port easily to any ANSI/POSIX-conforming UNIX. It has even been ported to OS/2 Warp!
The distribution includes the library and support utilities, including a terminfo compiler tic(1), a decompiler infocmp(1), clear(1), tput(1), tset(1), and a termcap conversion tool captoinfo(1). Full manual pages are provided for the library and tools.
The ncurses distribution is available via anonymous FTP at the GNU distribution site ftp://ftp.gnu.org/pub/gnu/ncurses.
It is also available at ftp://dickey.his.com/ncurses.
This release is designed to be upward compatible from ncurses 5.0; very few applications will require recompilation, depending on the platform. These are the highlights from the change-log since ncurses 5.0 release.
- made the extended terminal capabilities (
configure --enable-tcap-names) a standard feature (though the configure script can disable it, it is built by default).
- removed the
trace() function and related trace support from the production library. This is the only interface change that may cause problems with existing applications linked to shared libraries, since not all platforms use the minor version number.
- explicitly initialized to zero several data items which were implicitly initialized, e.g., cur_term. If not explicitly initialized, their storage type is C (common), and causes problems linking on some platforms.
- modified curses.h.in, undef'ing some symbols to avoid conflict with C++ STL.
Major bug fixes:
- modified infocmp -e, -E options to ensure that generated fallback.c type for Booleans agrees with term.h
- documented a special case of incompatiblity between ncurses 4.2 and 5.0, added a section for this in INSTALL.
- corrected tests for file-descriptors in OS/2 EMX mouse support. A negative value could be used by FD_SET, causing the select() call to wait indefinitely.
- made 'tput flash' work properly for xterm by flushing output in delay_output() when using napms(), and modifying xterm's terminfo to specify no padding character. Otherwise, xterm's reported baud rate could mislead ncurses into producing too few padding characters.
- modified lib_addch.c to allow repeated update to the lower-right corner, rather than displaying only the first character written until the cursor is moved. Recent versions of SVr4 curses can update the lower-right corner, and behave this way.
- modified echo() behavior of getch() to match Solaris curses for carriage return and backspace (reported by Neil Zanella).
- corrected offsets used for subwindows in
- modified configure script so AC_MSG_ERROR is temporarily defined to a warning in AC_PROG_CXX to make it recover from a missing C++ compiler without requiring user to add --without-cxx option
- corrected logic in lib_twait.c as used by lib_mouse.c for GPM mouse support when poll() is used rather than select().
- made several fixes for buffer overflows, unchecked recursion, improvements in performance, etc. See the NEWS file for details.
Features of Ncurses
The ncurses package is fully compatible with SVr4 (System V Release 4) curses:
- All 257 of the SVr4 calls have been implemented (and are documented).
- Full support for SVr4 curses features including keyboard mapping, color, forms-drawing with ACS characters, and automatic recognition of keypad and function keys.
- An emulation of the SVr4 panels library, supporting a stack of windows with backing store, is included.
- An emulation of the SVr4 menus library, supporting a uniform but flexible interface for menu programming, is included.
- An emulation of the SVr4 form library, supporting data collection through on-screen forms, is included.
- Binary terminfo entries generated by the ncurses tic(1) implementation are bit-for-bit-compatible with the entry format SVr4 curses uses.
- The utilities have options to allow you to filter terminfo entries for use with less capable curses/terminfo versions such as the HP/UX and AIX ports.
The ncurses package also has many useful extensions over SVr4:
- The API is 8-bit clean and base-level conformant with the X/OPEN curses specification, XSI curses (that is, it implements all BASE level features, but not all EXTENDED features). Most EXTENDED-level features not directly concerned with wide-character support are implemented, including many function calls not supported under SVr4 curses (but portability of all calls is documented so you can use the SVr4 subset only).
- Unlike SVr3 curses, ncurses can write to the rightmost-bottommost corner of the screen if your terminal has an insert-character capability.
- Ada95 and C++ bindings.
- Support for mouse event reporting with X Window xterm and OS/2 console windows.
- Extended mouse support via Alessandro Rubini's gpm package.
- The function
wresize() allows you to resize windows, preserving their data.
- The function
use_default_colors() allows you to use the terminal's default colors for the default color pair, achieving the effect of transparent colors.
- The functions
define_key() allow you to better control the use of function keys, e.g., disabling the ncurses KEY_MOUSE, or by defining more than one control sequence to map to a given key code.
- Support for 16-color terminals, such as aixterm and XFree86 xterm.
- Better cursor-movement optimization. The package now features a cursor-local-movement computation more efficient than either BSD's or System V's.
- Super hardware scrolling support. The screen-update code incorporates a novel, simple, and cheap algorithm that enables it to make optimal use of hardware scrolling, line-insertion, and line-deletion for screen-line movements. This algorithm is more powerful than the 4.4BSD curses quickch() routine.
- Real support for terminals with the magic-cookie glitch. The screen-update code will refrain from drawing a highlight if the magic- cookie unattributed spaces required just before the beginning and after the end would step on a non-space character. It will automatically shift highlight boundaries when doing so would make it possible to draw the highlight without changing the visual appearance of the screen.
- It is possible to generate the library with a list of pre-loaded fallback entries linked to it so that it can serve those terminal types even when no terminfo tree or termcap file is accessible (this may be useful for support of screen-oriented programs that must run in single-user mode).
- The tic(1)/captoinfo utility provided with ncurses has the ability to translate many termcaps from the XENIX, IBM and AT&T extension sets.
- A BSD-like tset(1) utility is provided.
- The ncurses library and utilities will automatically read terminfo entries from $HOME/.terminfo if it exists, and compile to that directory if it exists and the user has no write access to the system directory. This feature makes it easier for users to have personal terminfo entries without giving up access to the system terminfo directory.
- You may specify a path of directories to search for compiled descriptions with the environment variable TERMINFO_DIRS (this generalizes the feature provided by TERMINFO under stock System V.)
- In terminfo source files, use capabilities may refer not just to other entries in the same source file (as in System V) but also to compiled entries in either the system terminfo directory or the user's $HOME/.terminfo directory.
- A script (capconvert) is provided to help BSD users transition from termcap to terminfo. It gathers the information in a TERMCAP environment variable and/or a ~/.termcap local entries file and converts it to an equivalent local terminfo tree under $HOME/.terminfo.
- Automatic fallback to the /etc/termcap file can be compiled in when it is not possible to build a terminfo tree. This feature is neither fast nor cheap, you don't want to use it unless you have to, but it's there.
- The table-of-entries utility toe makes it easy for users to see exactly what terminal types are available on the system.
- The library meets the XSI requirement that every macro entry point have a corresponding function which may be linked (and will be prototype-checked) if the macro definition is disabled with
- An HTML "Introduction to Programming with NCURSES" document provides a narrative introduction to the curses programming interface.
State of the Package
Numerous bugs present in earlier versions have been fixed; the library is far more reliable than it used to be. Bounds checking in many `dangerous' entry points has been improved. The code is now type-safe according to gcc -Wall. The library has been checked for malloc leaks and arena corruption by the Purify memory-allocation tester.
The ncurses code has been tested with a wide variety of applications including (versions starting with those noted):
- Curses Development Kit
- the underlying application used in Slackware's setup, and the basis for similar applications on GNU/Linux.
- the character-screen WWW browser
- Midnight Commander 4.1
- file manager
- mail utility
- file-transfer utility
- New vi versions 1.50 are able to use ncurses versions 1.9.7 and later.
- newsreader, supporting color, MIME
- tape archive utility
- Volks-Hypertext browser for the Jargon File
as well as some that use ncurses for the terminfo support alone:
- terminal emulator
The ncurses distribution includes a selection of test programs (including a few games).
Who's Who and What's What
The original developers of ncurses are Zeyd Ben-Halim and Eric S. Raymond. Ongoing work is being done by Thomas Dickey and Jürgen Pfeifer. Thomas Dickey acts as the maintainer for the Free Software Foundation, which holds the copyright on ncurses. Contact the current maintainers at email@example.com.
To join the ncurses mailing list, please write email to
firstname.lastname@example.org containing the line:
This list is open to anyone interested in helping with the development and testing of this package.
Beta versions of ncurses and patches to the current release are made available at ftp://dickey.his.com/ncurses.
- Extended-level XPG4 conformance, with internationalization support.
- Ports to more systems, including DOS and Windows.
We need people to help with these projects. If you are interested in working on them, please join the ncurses list.
Other Related Resources
The distribution includes and uses a version of the terminfo-format terminal description file maintained by Eric Raymond. http://earthspace.net/~esr/terminfo.
You can find lots of information on terminal-related topics not covered in the terminfo file at Richard Shuford's archive.