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Mon, 8 Nov 2021 18:50:07 -0500
Announcing ncurses 6.3
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
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
* 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,
* 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
* tset, to initialize the terminal
Full manual pages are provided for the library and tools.
The ncurses distribution is available at ncurses' homepage:
It is also available via anonymous FTP at the GNU distribution site
These notes are for ncurses 6.3, released October 21, 2021.
This release is designed to be source-compatible with ncurses 5.0
through 6.2; 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, of course, numerous other improvements, listed in this
The most important bug-fixes/improvements dealt with portability
issues. The release notes also mention some other bug-fixes, but are
focused on new features and improvements to existing features since
ncurses 6.2 release.
There are a few new features:
* A new (experimental) driver, for the Windows Terminal
configuration is provided.
* A script is provided which enables OpenBSD users to upgrade their
system to use ncurses 6.3 (OpenBSD developers are also invited to
Additionally, to improve performance other changes (and extensions)
are provided in this release:
* modify lib_mouse.c to check for out-of-range button numbers,
convert those to position reports.
* add sp-funcs for erasewchar, killwchar.
These are revised features:
* modify wgetnstr, wgetn_wstr to improve compatibility with SVr4
curses in its treatment of interrupt and quit characters
These were done to limit or ultimately deprecate features:
* mark wgetch-events feature as deprecated.
+ prevent KEY_EVENT from appearing in curses.h unless the
configure option --enable-wgetch-events is used.
+ modify MKkey_defs.sh to hide ncurses' definition of
KEY_EVENTS to reduce Visual Studio C++ redefinition warnings.
* reduce build-warnings by excluding ncurses-internals from
These are improvements to existing features:
* drop symbols GCC_PRINTF and GCC_SCANF from <curses.h>, to simplify
* apply gcc format attribute to prototypes which use a va_list
parameter rather than a "..." variable-length parameter list.
* modify <term.h> so that it is not necessary to include <curses.h>
* provide for wide-characters as background character in wbkgrnd
* improve parameter-checking for tparm, adding function _nc_tiparm()
to handle the most-used case, which accepts only numeric
* use return-value from vsnprintf to reallocate as needed to allow
for buffers larger than the screen size.
* add another fflush(stdout) in _nc_flush to handle time-delays in
the middle of strings such as flash when the application uses
low-level calls rather than curses.
These are corrections to existing features:
* add a check to guard against repeat_char emitting digits which
could be interpreted as BSD-style padding when --enable-bsdpad is
* check for screen size-change in scr_init and scr_restore, in case
a screen dump does not match the current screen dimensions
Several improvements were made to the utility programs:
+ implement "+m" option
+ add check for duplicate "use=" clauses.
+ add check to report instances where tparm would detect an
error in an expression.
+ add user-defined capabilities from mintty to Caps-ncurses,
for checking consistency.
+ improve warning when oc/op do not mention SGR 39/49 for xterm
compatible XT flag.
+ improve checks for number of parameters of smglp, smgrp,
smgtp, and smgbp.
+ improve "-c" option to validate the number and type of
parameters and compare against expected number/type before
deciding which set of parameter-lists to use in tparm calls.
+ improve check for errors detected in tparm.
+ improve format of output, to ensure that the messages contain
only printable text.
+ modify to eliminate unnecessary "\" to escape ":" in terminfo
+ remove check that assumes that none or both parameterized and
non-parameterized margin-setting capabilities are present.
+ modify output of "toe -as" to show first description found
rather than the last.
+ add a check to ensure that a "termcap file" is text rather
+ modify to allow multiple commands per line.
+ improve parameter-checking by analyzing all extended string
capabilities, e.g., as used in the Cs and Ms capabilities of
the tmux description.
+ make warning messages consistently using alias names when
those are used, rather than the underlying program's name.
+ improve usage message for aliases such as clear, by
eliminating tput-specific portions.
+ modify initialization to avoid opening /dev/tty for cases
other than reset/init, e.g., for clear.
Along with the library and utilities, improvements were made to the
ncurses-examples. Most of this activity aimed at improving the
test-packages. A few changes are more generally useful, e.g., for the
main ncurses test-program, and for analyzing traces using the
* add "-r" option to the dots test-programs, to help with scripting
a performance comparison.
* build-fix for test_opaque, for configurations without opaque
curses structs, e.g., ncurses 5.7.
* improve tracemunch logic for "RUN" compaction.
* improve tracemunch's coverage of form/menu/panel libraries.
* improve tracemunch's checking/reporting the type for the first
parameter, e.g., "WINDOW*" rather than "#1".
* modify tracemunch and the panel library to show readable traces
for panel- and user-pointers.
There are other new demo/test programs and reusable examples:
to exercise the wide-character background functions.
to demonstrate move_field, and a stub for a corresponding demo
for checking tparm changes.
There are several new terminal descriptions:
absolute, att610+cvis, foot, foot-direct, hp98550-color,
hpterm-color2, hterm, hterm-256color, linux-s, putty+keypad,
putty+screen, putty-screen, screen.linux-s, scrt/securecrt,
tmux-direct, vt220+cvis, vt220+cvis8, vt220+pcedit, vt220+vtedit,
vt220-base, vt52+keypad, xterm+256color2, xterm+88color2,
xterm-direct16, xterm-direct256, xterm+nofkeys, and
There are many changes to existing terminal descriptions. Some were
updates to several descriptions:
* correct use-ordering in some xterm-direct flavors
* fix some sgr inconsistencies in d230c, ibm6153, ibm6154,
* improve vt50h and vt52 based on DECScope manual
* use hp+arrows in a few places
* use hp+pfk-cr in a few places
* use vt220+cvis in st, terminology, termite since they ignore
blinking-cursor detail in att610+cvis
while others affected specific descriptions. These were retested, to
take into account changes by their developers:
kitty+common, mlterm3, ms-terminal
while these are specific fixes based on reviewing documentation, user
reports, or warnings from tic:
use att610+cvis, xterm+tmux and ansi+enq
fix pound-sign mapping in acsc
modify to reflect default mapping of shift-tab by kbd 1.14
fill in some missing pieces, to make it comparable to the vt220
use vt100+fnkeys, add rep
corrected tsl capability
change kbs to ^?
add smglp and smgrp
A few entries use extensions (user-defined terminal capabilities):
* add shifted Linux console keys in linux+sfkeys entry for
* add Smulx to alacritty
* add kbeg to xterm+keypad to accommodate termcap applications
* add extensions in xterm+tmux and ecma+strikeout to ms-terminal,
but cancel the non-working Cr and Ms capabilities
As usual, this release
* improves documentation by describing new features,
* attempts to improve the description of features which users have
* 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,
+ make opts extension for getcchar work as documented for
ncurses 6.1, adding "-g" flag to demo_new_pair to illustrate.
+ modify tset "-q" option to refrain from modifying terminal
modes, to match the documentation.
* New/improved history and portability sections:
+ improve documentation for tparm and static/dynamic variables.
+ add history note to curs_scanw.3x for <stdarg.h> and
+ add history note to curs_printw.3x for <stdarg.h> and
+ add portability note to ncurses.3x regarding <stdarg.h>
+ add historical notes to tput, curses-terminfo and
curses-color manpages based on source-code for SVr2, SVr3 and
+ improve history section for tset manpage based on the 1BSD
tarball, which preceded BSD's SCCS checkins by more than
* Other improvements:
+ explain in ncurses.3x that functions in the tinfo library do
not rely upon wide-characters.
+ improve manual page for panel library, extending the
portability section as well as documenting error-returns.
+ add section on margins to terminfo.5, adapted from X/Open
+ improve man/term.5 section on legacy storage format.
+ add a note in terminfo.5 explaining that no-parameter strings
such as sgr0 or cnorm should not be used with tparm.
+ improve description of BSD-style padding in curs_termcap.3x
+ improve discussion of padding versus tparm and tputs in
+ add a note in manual page to explain ungetch vs unget_wch.
+ improve description of error-returns in waddch and waddnstr
There are no new manual pages (all of the manual page updates are to
Some of the improvements are more subtle, relating to the way the
information is presented. For instance, hyphenation is suppressed in
the HTML files generated from manual pages because an upgrade to groff
gave noticeably poorer results, interfering with the process of
creating links between the resulting webpages.
While there were many bugs fixed during development of ncurses 6.3,
only a few (the reason for this release) were both important and
interesting. Most of the bug-fixes were for local issues which did not
affect compatibility across releases. Since those are detailed in the
NEWS file no elaboration is needed here.
The interesting bugs were:
* modify wbkgd and wbkgrnd to avoid storing a null in the background
character, because it may be used in cases where the corresponding
0x80 is not treated as a null.
This was a regression introduced in ncurses 6.2 (reported on the
mailing list), for which the workaround was to specify a blank for
the background character.
* remove output-related checks for nl/nonl (also reported on the
* improve tparm implementation of %P and %g, more closely matching
SVr4 terminfo. Those denote static and dynamic variables in
Exactly what those terms meant was never documented before in any
implementation of curses, aside from source code. Unlike the other
two fixes, the problem was discovered while studying OpenBSD's
version of tset.
There are no major changes. Several new options were added to ease
integration of packages with systems using different versions of GNAT
and ncurses. Also, improvements were made to configure checks.
There are a few new/modified configure options:
new configure option and check for gcc -fvisibility=hidden
corrected to allow turning leak-checking off later in a set of
new configure option makes the _Noreturn keyword optional to
revised option also controls whether $LDFLAGS from the build is
provided in "-config" and ".pc" files.
add configure option which tells ncurses to disallow most
file-opens by setuid processes.
changed default to help packagers who reuse wide ncursesw
header file with non-wide ncurses library.
revised option uses the actual search path from pkg-config or
pkgconf using the output from --debug.
new several --with-xxx-libname options, to help with pkgsrc
Many of the portability changes are implemented via the configure
* add a special case in the configure script to work around one of
the build-time breakages reported for OpenBSD 6 here:
* modify configure check for libtool to prevent accidental use of an
OpenBSD program which uses the same name.
* modify configuration checks for build-time tic/infocmp to use
AC_CHECK_TOOL. That can still be overridden by --with-tic-path and
--with-infocmp-path when fallbacks are used, but even if not using
fallbacks, the improved check may help with cross-compiling.
* relax modification-time comparison in CF_LINK_FUNCS to allow it to
accept link() function with NFS filesystems which change the mtime
on the link target, e.g., several BSD systems.
* modify configure check for c89/c99 aliases of clang to use its
-std option instead, because some platforms, in particular macOS,
do not provide workable c89/c99 aliases.
* modify CF_NCURSES_CONFIG to work around Xcode's c99 "-W" option,
which conflicts with conventional use for passing linker options.
* modify configure scripts to filter out redefinitions of
_XOPEN_SOURCE, e.g., for NetBSD which generally supports 500, but
600 is needed for ncursesw.
Here are some of the other portability fixes:
* change configure-check and source-code for gcc's noreturn
attribute to assume it is a prefix rather than suffix, matching
c11's _Noreturn convention.
* modify mk-1st.awk to account for extra-suffix configure option.
* build-fix for termsort module when configured with termcap.
* modify configure script and makefiles to support ".PHONY" make
* amend libtool configuration to add dependency for install.tic,
etc., in ncurses/Makefile on the lower-level libraries.
* modify Ada95 source-generation utility to write to a file given as
parameter rather than to the standard output, allowing builds with
* amend tic/infocmp check to allow for the respective tool's
* build-fixes for gnat 10.1.1, whose gnatmake drops integration with
* correct configure version-check/warning for g++ to allow for 10.x
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 all of the for SVr4 curses features including
keyboard mapping, color, forms-drawing with ACS characters, and
automatic recognition of keypad and function keys.
* ncurses provides these SVr4 add-on libraries (not part of X/Open
+ the panels library, supporting a stack of windows with
+ the menus library, supporting a uniform but flexible
interface for menu programming.
+ the form library, supporting data collection through
* ncurses's terminal database is fully compatible with that used by
+ ncurses supports user-defined capabilities which 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
* 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 most 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
* 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
* The function use_default_colors allows you to use the terminal's
default colors for the default color pair, achieving the effect of
* 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
* 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
* 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
* 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
* 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.
* The library meets the XSI requirement that every macro entry point
has a corresponding function which may be linked (and will be
prototype-checked) if the macro definition is disabled with
* 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
The ncurses library has been tested with a wide variety of
FrontEnd to Apt, the debian package manager
Curses Development Kit
the underlying application used in Slackware's setup, and the
basis for similar install/configure applications on many
the text WWW browser
New vi uses ncurses.
A console file manager with VI key bindings in Python.
newsreader, supporting color, MIME
File manager with vi like keybindings
as well as some that use ncurses for the terminfo support alone:
terminal emulator for serial modem connections
a replacement for ssh.
terminfo action checker
vi-like-emacs may be built to use the terminfo, termcap or
and finally, those which use only the termcap interface:
The most commonly used pager (a program that displays text
Zeyd Ben-Halim started ncurses from a previous package pcurses,
written by Pavel Curtis. Eric S. Raymond continued development.
Juergen 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
Contact the current maintainers at
To join the ncurses mailing list, please write email to
containing the line:
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
Patches to the current release are made available at
There is an archive of the mailing list here:
http://lists.gnu.org/archive/html/bug-ncurses (also https)
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
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
You can find lots of information on terminal-related topics not
covered in the terminfo file at Richard Shuford's archive . The
collection of computer manuals at bitsavers.org has also been useful.
* Release Notes
+ Library improvements
o New features
o Other improvements
+ Program improvements
+ Terminal database
+ Interesting bug-fixes
+ Configuration changes
o Major changes
o Configuration options
* Features of ncurses
* Applications using ncurses
* Development activities
* Related resources
* Other resources
Thomas E. Dickey <firstname.lastname@example.org>
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