Announcing ncurses 6.6 Overview
The ncurses (new curses) library is a free software emulation of
curses in System V Release 4.0 (SVr4), 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 SVr4-curses
enhancements over BSD curses. SVr4 curses became the basis of X/Open
Curses.
In mid-June 1995, the maintainer of 4.4BSD curses declared that he
considered 4.4BSD curses obsolete, and encouraged the keepers of unix
releases such as BSD/OS, FreeBSD and NetBSD to switch over to ncurses.
Since 1995, ncurses has been ported to many systems:
* It is used in almost every system based on the Linux kernel (aside
from some embedded applications).
* It is used as the system curses library on OpenBSD, FreeBSD and
MacOS.
* It is used in environments such as Cygwin and MinGW. The first of
these was EMX on OS/2 Warp.
* It is used (though usually not as the system curses) on all of the
vendor unix systems, e.g., AIX, HP-UX, IRIX64, SCO, Solaris,
Tru64.
* It should work readily on any ANSI/POSIX-conforming unix.
The distribution includes the library and support utilities, including
* captoinfo, a termcap conversion tool
* clear, utility for clearing the screen
* infocmp, the terminfo decompiler
* tabs, set tabs on a terminal
* tic, the terminfo compiler
* toe, list (table of) terminfo entries
* tput, utility for retrieving terminal capabilities in shell
scripts
* tset, to initialize the terminal
Full manual pages are provided for the library and tools.
The ncurses distribution is available at ncurses' homepage:
https://invisible-island.net/archives/ncurses/ or
https://invisible-mirror.net/archives/ncurses/ .
It is also available at the GNU distribution site
https://ftp.gnu.org/gnu/ncurses/ .
Release Notes
These notes are for ncurses 6.6, released December 30, 2025.
This release is designed to be source-compatible with ncurses 5.0
through 6.5; providing extensions to the application binary interface
(ABI). Although the source can still be configured to support the
ncurses 5 ABI, the reason for the release is to reflect improvements
to the ncurses 6 ABI and the supporting utility programs.
There are numerous other improvements listed in this announcement.
The most important bug-fixes/improvements dealt with robustness
issues. The release notes also mention some other bug-fixes, but are
focused on new features and improvements to existing features since
ncurses 6.5 release.
Library improvements
Terminal driver improvements
This release focuses on improvements to the MinGW/Windows terminal
driver. The terminal driver for MinGW32 was introduced in 2009. A new
version of the terminal driver to support Windows Terminal was begun
in 2020. However, there were some differences:
* Both drivers use Console API; the later Windows driver also
provides for using character escape sequences.
* The MinGW32 driver was designed to imitate POSIX terminal I/O data
types to simplify integration with the existing sources.
The newer Windows driver did not integrate with the sources in the
same way. In particular, the reset utility was incomplete.
* Windows Terminal support for Console API is incomplete, lacking
mouse support. Additionally, its developers took a few years to
resolve issues with carriage-return versus line-feed translation.
Reflecting on these problems, both MinGW and Windows drivers are
still provided in ncurses through the current release.
* The two drivers are similar, but in developing the Windows driver
some renaming and refactoring was done. That resulted in duplicate
source files. This release eliminates the duplication.
These improvements have been made to the terminal driver:
* made win_driver.c obsolete in favor of win32_driver.c
* made win32_curses.h obsolete in favor of nc_win32.h
* added configure check for Win32 named pipes feature, using that to
make nc_mingw.h obsolete in favor of nc_win32.h
* separated the _NC_WINDOWS platform macro into _NC_WINDOWS_NATIVE,
for MinGW and other native Win32 support, and _NC_WINDOWS, to make
some Win32 features available under the Cygwin runtime, in this
case the term-driver.
* modified MinGW32 configuration to account for its use of
Windows-style pathnames in filesystem checks.
* changed MS_TERMINAL symbol to DEFAULT_TERM_VAR
* updated ncurses/wcwidth.c, for MinGW ports, from xterm.
* made fixes for reading Unicode characters in MinGW/Windows port
* improved Windows driver by restoring the scroll buffer and console
mode, e.g., when reset_prog_mode or endwin is called
* simplified include for wchar.h in Windows port by removing the
platform ifdef's
* modified driver for MinGW to handle shift-tab and control-tab as
back-tab
* made fixes for port using clang-cl or cl MSVC
Other improvements
These are improvements to existing features:
* add comments to generated term.h to hint the configure options
used
* change scope of TTY, GET_TTY and SET_TTY to ncurses-internals
* improved mouse driver
+ modify handle_wheel case 2 to ignore the event as in case 1
for mouse version 1, since that corresponds to a button 6 or
7 event which is not supported with ABI 6.
+ use separate read/write pointers in the mouse event queue to
work with too-close events for the click-detection to work
reliably, and further improve that in case mouseinterval(0)
is used to suppress click-detection.
* modify treatment of “n” parameter for waddnstr, waddnwstr, and
wins_nwstr to return OK when “n” is zero, for consistency with
other implementations
* modify wattron/wattroff calls in form/m_post.c to call wattr_on
and wattr_off to omit cast used in the former for X/Open
compatibility
* change winwstr to a generated function, using the macro
definition, moving its handling of negative length parameter into
winnwstr.
* change winwstr to return wide character count instead of OK.
* disallow directories and block/character devices in safe-open.
* amend scr_restore and scr_init to remove the target window only
after validating the source window which will replace the target
* modify _nc_flush to also flush stderr to help the flash capability
to work in bash
* trim padding from sgr expression used in trim_sgr0, to avoid
copying the padding into the resulting sgr0
* modify misc/Makefile.in and misc/run_tic.in so that $DESTDIR is
set and used only in the makefile.
* modify MKfallback.sh to eliminate TERMINFO environment variable.
* add -x option to infocmp in MKfallback.sh
* limit value from ESCDELAY environment variable to 30 seconds, like
other delay limits.
* limit values from LINES and COLUMNS environment variables to 512
* added check in wresize for out-of-range dimensions
* improved error-handling in c++ binding
* improved error-reporting in write_entry.c
* amended limit used in alloc_pair, by applying an adjustment for
default colors only when the maximum number of color pairs is
greater than the maximum number of colors
* added limit-checks in alloc_entry.c and alloc_ttype.c to avoid
indexing errors when using infocmp to compare all capabilities
when processing a malformed terminfo binary which has a valid
header
* added a null pointer check in mouse-initialization, for the
Windows driver
* added some null-pointer checks after mallocs in test-programs.
These are corrections to existing features:
* removed test in wgetch which applied notimeout to the initial read
of a character
* added check for special case of wcrtomb converting a single byte
code to a different single byte code, which glibc does for code
160 in the KOI8-R encoding
* corrected _nc_to_char for the case when wctob is not found by
configure script
* revised loop in wins_nwstr, to ensure that non-spacing characters
are combined with the base spacing character
* modified checks in delwin to avoid checking if the window is a pad
until first checking if it is still on the active window-list
Program improvements
Utilities
Several improvements were made to the utility programs.
infocmp
+ improved infocmp -E/-e fallback feature
o prefix names with “ti_” if they begin with a digit,
e.g., 9term
o escape backslashes and double-quotes in description
fields
+ modified infocmp -E/-e fallback feature to reduce stricter
compiler warnings for the extended capability data.
+ modified infocmp and tabs to use actual name in usage and
header.
+ improved error-message from infocmp when a terminal entry
cannot be opened
tic
+ increased limit on use-clauses from 32 to 40, warn but allow
entries which exceed the old limit.
+ added check for infinite loop in tic's use-resolution.
+ added a buffer-limit check in postprocess_termcap
tput
+ Warn about capabilities which expect parameters where none
are given. Also, repair the feature where multiple
capabilities can be handled on a single line.
Examples
Along with the library and utilities, improvements were made to the
ncurses-examples:
* add help-popup for test_instr.c, test_inwstr.c
* add options to test/worm.c for benchmarking.
* improve -t option of test/gdc.c, allowing hours only, or hours and
minutes only.
* correct dimensions in test/popup_msg.c, fixing an overrun.
* modify test/demo_keyok.c to accept ^Q for quit, for consistency.
* add option “-c” to test programs to illustrate a non-blank
character in the window background property.
* reserve -c/-l options in test/*.c for command/logging like vttest.
There is one new demo/test program:
ncurses/report_ctype.c
Shows a chart of the first 256 character codes, which are not
as consistent across platforms for ctype versus wctype as some
suppose.
Terminal database
There are several new terminal descriptions:
* ghostty
* illumos, sun-16color, sun-256color, and sun-direct
* ms-terminal-direct
* pangoterm
* rlogin-color
* sclp
* vt520-w and vt525-w
along with building blocks
* linux+lockeys, xterm+r5+lockeys, xterm+r5+fkeys
* vt100+pf1-pf4
* vt220+ufkeys, vt220+sfkeys
* ecma+standout, ecma+underline
* wyse+cvis
There are many changes to existing terminal descriptions. Some were
updates to several descriptions, using the infocmp “-u” option in a
script to determine which building-block entries could be used to
replace multiple capability settings (and trim redundant information).
Other changes include:
* use xterm+keypad in pccon+base
* use bracketed+paste in nsterm, rlogin-color, screen, terminology
* use extended-keys in djgpp 2.05
* update/correct some of the rv/xr strings, checked with
tack
+ add rv code for alacritty
+ add xr code for putty
+ add rv/xr codes for domterm, mintty, mlterm, contour,
ghostty, iterm2, kitty, konsole, vscode, vte, wezterm
* improve use-clauses: ansi+cup, ansi+idl1, ansi+rca, ansi+rca2,
ansi+sgrso, ansi+sgrul
* sclp:
+ add kf1 to kf5
+ use ansi+rca
+ use vt220+pcedit
* vt525
+ add color
+ add op
* wezterm:
+ use xterm+alt+title
+ omit its broken left/right margin feature
* update contour
* update ms-terminal
+ add XM/xm to ms-terminal, to enable mouse with experimental
Windows driver
* update st to 0.8.5
* update teraterm to 5.0
* update foot to 1.18.1
* update iTerm2 to 3.5.0
Documentation
As usual, this release
* improves documentation by describing new features,
* attempts to improve the description of features which users have
found confusing
* fills in overlooked descriptions of features which were described
in the NEWS file but treated sketchily in manual pages.
In addition to providing background information to explain these
features and show how they evolved, there are corrections,
clarifications, etc.:
* Corrections:
+ corrected note about box() in curs_border.3x
+ added note on scrolling and lower-right corner to waddch and
wadd_wch manual pages.
* Other improvements:
+ This release has many changes to improve the formatting and
style of the man pages.
+ Table layout in the man pages has been revised.
+ The ncurses HOWTO and its sample programs has been updated.
There are no new manual pages (all of the manual page updates are to
existing pages).
Interesting bug-fixes
Configuration changes
Major changes
Improvements made to configure checks include
* improve configure check for “install”.
* add check for build-time utilities, in case cross-compiling is
setup with an invalid $BUILD_CC
* add configure check for <sys/fsuid.h>, which may be needed for
flatpacks
* add a consistency-check for termio(s)/tty headers, to help with
cross-compiles
* modify configure check for MAKEFLAGS/MFLAGS to ignore existing
value of these environment variables
* improve configurability of alloca as used in Windows ports.
* modify configure script checks for stdbool.h to fix build with
older gcc version.
* add <new> to the possible headers declaring the C++
std::bad_alloc.
* modify check for stdbool.h to be more conservative in case the
headers are used with a compiler other than that which was used to
configure
* remove dependency on stdbool.h from configure script check for
type of bool when C++ binding is omitted.
Configuration options
There are a few new configure options:
--enable-install-prefix
Modify behavior of $DESTDIR to merge or replace the value set
by --prefix.
--enable-named-pipes
The Windows driver uses named pipes for communicating with a
pseudo console, allowing it to use escape sequences rather than
Console API. This works well with mintty. On the downside, this
feature may not work well with the Windows Terminal due to a
longstanding bug in conhost.exe (#9461).
These configure options are modified:
--enable-exp-win32
This option is obsolete, replaced by --enable-named-pipes.
--enable-term-driver
This is enabled by default on platforms where the Windows
driver can be compiled, e.g., Cygwin, MinGW32 and MSYS2.
Package configuration scripts
The configure script and makefiles optionally generate a script which
reports the compiler and linker options needed to build a program with
ncurses, as well as a data file which is used via pkg-config for the
same purpose. Several improvements were made for these scripts:
* improved filtering of -L options in misc/gen-pkgconfig.in and in
misc/ncurses-config.in
* modified ncurses*-config to add -I option in --cflag where needed
for --disable-overwrite to match ".pc" files.
* suppressed -g and -fXXX flags from CFLAGS in
misc/ncurses-config.in
* modified configure script to allow for pkg-config using
DOS/Windows pathname syntax
* modified misc/ncurses-config.in, improved match with pkg-config
output.
* adjusted naming of test packages for MinGW *-config scripts to
match the pkg-config names
* added --cflags-only-I and --cflags-only-other options to
misc/ncurses-config.in
Portability
Many of the portability changes are implemented via the configure
script:
* disallow configure options which apply only to multiuser systems,
to improve ports to single-user systems such as Haiku
* add warning to configure script to address conflict between the
--enable-lp64 option and the options for overriding the types used
for chtype and mmask_t.
* modify configure script cases for $host_os, to accommodate 64-bit
big-endian POWER Linux with glibc
* modify configure script and misc/Makefile to accept glob
expressions that include Windows/DOS drive-letters
* change Ada95/configure to use --with-screen option rather than
--enable-widec, to provide more choices of underlying curses
library.
* modify configure script to work around broken gnatgcc script found
in gcc-13 builds.
Other portability fixes include:
* improve pattern used for configure --with-xterm-kbs option.
* modify recursive make rules to avoid interference with GNU make's
"-j" option
* when installing the terminfo database, check if symbolic links are
supported before attemping to link lib/terminfo from
share/terminfo
* improve logic in misc/run_tic.in for constructing symbolic link
when $DESTDIR is set.
* build-fix for ncurses-examples with newer PDCurses, which no
longer has stubs for unimplemented features.
* change etip.h.in to include either/both of <new> and <exception>,
needed for another old BSD.
* correct conditional-compile for a case when the C compiler does
not have a bool type.
* improve MKlib_gen.sh handling of “bool” type, for building
link_test.
* modify ncurses/tinfo/MKfallback.sh to work with MacOS sed, which
lacks BSD-style \< and \>.
* modify MKlib_gen.c to allow for Solaris's definition of NULL as
0L.
* widen pattern in pc/*-config scripts to disallow more linker
options.
* avoid redefining bool in curses.h if the platform already supports
that type.
* move include <curses.h> from etip.h.in to cursesw.h, to work
around breakage in Apple's port of ncurses.
_________________________________________________________________
Features of ncurses
The ncurses package is fully upward-compatible with SVr4 (System V
Release 4) curses:
* All of the SVr4 calls have been implemented (and are documented).
* ncurses supports the features of SVr4 curses including keyboard
mapping, color, form drawing with ACS characters, and automatic
recognition of keypad and function keys.
* ncurses provides work-alike replacements of SVr4 supplemental
libraries based on curses, but which were not specified by X/Open
Curses:
+ the panel library, permitting windows to stack and overlap
+ the menu library, supporting a uniform but flexible interface
for menu programming
+ the form library, supporting data collection through
on-screen forms
* ncurses's terminal database is fully compatible with that used by
SVr4 curses.
+ ncurses supports user-defined capabilities that it can see,
but which are hidden from SVr4 curses applications using the
same terminal database.
+ It can be optionally configured to match the format used in
related systems such as AIX and Tru64.
+ Alternatively, ncurses can be configured to use hashed
databases rather than the directory of files used by SVr4
curses.
* The ncurses 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, and almost all EXTENDED features). It includes
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 FreeBSD
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 keyok and 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 direct-color terminals, such as modern xterm.
* Support for 256-color terminals, such as modern xterm.
* Support for 16-color terminals, such as aixterm and modern 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/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 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.
* The table-of-entries utility toe makes it easy for users to see
exactly what terminal types are available on the system.
* X/Open Curses permits most functions it specifies to be made
available as macros as well. ncurses does this
+ to improve performance, e.g., for operations composed of
simpler functions such as cursor movement following by adding
text to the screen,
+ to simplify the implementation by reusing functions which use
common parameters, e.g., the standard screen stdscr, and
+ to provide functions that return values via their parameters
Except for the last case, ncurses provides a non-macro
implementation of the function. If the macro definition is
disabled with #undef, or by defining NCURSES_NOMACROS the function
may be linked (and its calls will be checked against the
prototype).
* Extensive documentation is provided (see the Additional Reading
section of the ncurses FAQ for online documentation).
Applications using ncurses
The ncurses distribution includes a selection of test programs
(including a few games). These are available separately as
ncurses-examples
The ncurses library has been tested with a wide variety of
applications including:
aptitude
FrontEnd to Apt, the debian package manager
https://wiki.debian.org/Aptitude
cdk
Curses Development Kit
https://invisible-island.net/cdk/
ded
directory-editor
https://invisible-island.net/ded/
dialog
the underlying application used in Slackware's setup, and the
basis for similar install/configure applications on many
systems.
https://invisible-island.net/dialog/
lynx
the text WWW browser
https://lynx.invisible-island.net/
mutt
mail utility
http://www.mutt.org/
ncftp
file-transfer utility
https://www.ncftp.com/
nvi
New vi uses ncurses.
https://sites.google.com/a/bostic.com/keithbostic/the-berkeley-
vi-editor-home-page
ranger
A console file manager with VI key bindings in Python.
https://ranger.github.io/
tin
newsreader, supporting color, MIME
http://www.tin.org/
vifm
File manager with vi like keybindings
https://vifm.info/
as well as some that use ncurses for the terminfo support alone:
minicom
terminal emulator for serial modem connections
https://salsa.debian.org/minicom-team/minicom
mosh
a replacement for ssh.
https://mosh.org/
tack
terminfo action checker
https://invisible-island.net/ncurses/tack.html
tmux
terminal multiplexor
https://github.com/tmux/tmux/wiki
vile
vi-like-emacs may be built to use the terminfo, termcap or
curses interfaces.
https://invisible-island.net/vile/
and finally, those which use only the termcap interface:
emacs
text editor
https://www.gnu.org/software/emacs/
less
The most commonly used pager (a program that displays text
files).
http://www.greenwoodsoftware.com/less/
screen
terminal multiplexor
https://www.gnu.org/software/screen/
vim
text editor
https://www.vim.org/
Development activities
Zeyd Ben-Halim started ncurses from a previous package pcurses,
written by Pavel Curtis. Eric S. Raymond continued development. Jürgen
Pfeifer wrote most of the form and menu libraries.
Ongoing development work is done by Thomas E. Dickey. Thomas E. Dickey
has acted as the maintainer for the Free Software Foundation, which
held a copyright on ncurses for releases 4.2 through 6.1. Following
the release of ncurses 6.1, effective as of release 6.2, copyright for
ncurses reverted to Thomas E. Dickey (see the ncurses FAQ for
additional information).
Contact the current maintainers at
[email protected]
To join the ncurses mailing list, please write email to
[email protected]
containing the line:
subscribe <name>@<host.domain>
This list is open to anyone interested in helping with the development
and testing of this package.
Beta versions of ncurses are made available at
https://invisible-island.net/archives/ncurses/current/ and
https://invisible-mirror.net/archives/ncurses/current/ .
Patches to the current release are made available at
https://invisible-island.net/archives/ncurses/6.5/ and
https://invisible-mirror.net/archives/ncurses/6.5/ .
There is an archive of the mailing list here:
https://lists.gnu.org/archive/html/bug-ncurses .
Related resources
The release notes make scattered references to these pages, which may
be interesting by themselves:
* ncurses licensing
* Symbol versioning in ncurses
* Comments on ncurses versus slang (S-Lang)
* Comments on OpenBSD
* tack – terminfo action checker
* tctest – termcap library checker
* Terminal Database
Other resources
The distribution provides a newer version of the terminfo-format
terminal description file once maintained by Eric Raymond . Unlike the
older version, the termcap and terminfo data are provided in the same
file, which also provides several user-definable extensions beyond the
X/Open Curses specification.
You can find lots of information on terminal-related topics not
covered in the terminfo file in Richard Shuford's archive (original).
The collection of computer manuals at bitsavers.org has also been
useful.
* Overview
* Release Notes
+ Library improvements
o Terminal driver
o Other improvements
+ Program improvements
o Utilities
o Examples
+ Terminal database
+ Documentation
+ Interesting bug-fixes
+ Configuration changes
o Major changes
o Configuration options
o Package configuration scripts
+ Portability
* Features of ncurses
* Applications using ncurses
* Development activities
* Related resources
* Other resources
--
Thomas E. Dickey <[email protected]>
https://invisible-island.net
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