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:
The distribution includes the library and support utilities, including
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
These notes are for ncurses 6.5, released April 27, 2024.
This release is designed to be source-compatible with ncurses 5.0 through 6.4; 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 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 6.4 release.
These are new features:
The low-level terminfo and termcap interfaces are used both by the higher-level curses library, as well as by many applications.
The functions which convert parameterized terminal
capability strings for output to the terminal
(tiparm and tparm) analyze the
capability string to determine which parameters are strings
(i.e., addresses), versus numbers (not addresses).
The library's analysis of a capability string may differ from the calling application's design if environment variables are used to point to an invalid terminal database. This is a longstanding problem with all implementations of terminfo, dating from the early 1980s.
Two new functions address this problem: by providing a function which allows the calling application to tell ncurses how many string-parameters to expect:
tiscan_s helps applications check
formatting capabilities that would be passed to
tiparm_s.tiparm_s provides applications a way to
tell ncurses what the expected parameters are for a
capability.The ncurses library supports a compile-time feature
(enabled with the configure --enable-check-size
option) which simplifies initialization with terminals which
do not negotiate window (screen) size. This is done in
setupterm, by providing for using ANSI
cursor-position report (in user6/user7 terminfo capabilities)
to obtain the screen size if neither environment variables or
ioctl is used.
The ncurses test-program with options
“-E -T” demonstrates this
feature.
SCREENThis release drops compatibility with obsolete versions of tack, e.g., pre-1.08
These are improvements to existing features:
In addition to the new, safer function
tiparm_s, ncurses adds checks to make the older
tiparm, tparm and
tgoto functions safer:
the terminfo functions tiparm and
tparm ensure that the capability string
comes from the terminal description which ncurses loads,
rather than from random data which the application
happens to have.
the tgoto function disallows capabilities
which its analysis shows will attempt to use string
parameters.
ncurses uses internal functions which correspond to
tiparm, and tgoto which ensure
that the capability strings which are passed to these
functions come from the loaded terminal description.
improve check in lib_tparm.c, ensuring that a
char* fits into a TPARM_ARG
modify _nc_syserr_abort to use
_nc_env_access, rather than only checking root
uid
improve thread lock in lib_trace.c
modify flushinp to use file descriptors in
SCREEN, rather than from TERMINAL,
and check if they are for a terminal, like SVr4
modify mcprint to use file descriptor in
SCREEN, for consistency
modify internal function _nc_read_file_entry
to show relevant filename in warnings
improve checks in internal function
convert_string for corrupt terminfo entry
review/improve handling of out-of-memory conditions
limit delays to 30 seconds, i.e., padding delays in
terminfo, as well as napms and
delay_output functions
fix reallocation loop for vsnprintf in
_nc_sprintf_string by copying the va_list
variable
modify delscreen to limit the windows which
it creates to just those associated with the screen
modify endwin to return an error if it is
called again without an intervening screen update
modify wenclose to handle pads
eliminate use of PATH_MAX in
lib_trace.c
provide for any CCHARW_MAX greater than 1
These are corrections to existing features:
correct loop termination condition in
waddnstr and waddnwstr
improve parsing in internal function
_nc_msec_cost, allowing a single decimal
point
amend parameter check for entire string versus specific
length in winsnstr and wins_nwstr
to match Solaris; make similar correction to
wins_nwstr
correct internal function wadd_wch_literal
when adding a non-spacing character to a double-width
character
correct definition of Charable macro for
non-wide ncurses library .
Several improvements were made to the
utility programs. Some were done to make the infocmp
option “-u” option help refactor the
terminal database.
add limit checks for processing extended capabilities
with the “-u” option
correct initial alignment of extended capabilities, so
that the “-u” option can be used
for more than two terminal types
modify “-u” option to not
report cancels for strings which were already cancelled
in a use'd chunk.
correct an assignment “-u”
for detecting if a boolean is unset in a base entry and
set in a use'd chunk, i.e., if it was cancelled.
correct limit-check when dumping tc/use clause via
“-I”
check return value of _nc_save_str, in
special case where extended capabilities are processed
but the terminal description was not initialized
modify check for multiply defined aliases to report problems within the current runtime rather than for conflicts with pre-existing terminal descriptions.
disallow using $TERMINFO or
$HOME/.terminfo when
“-o” option is used
add “-v” option to tput, to
show warnings
modify reset command to avoid altering clocal if the terminal uses a modem
modify reset feature to avoid 1-second sleep if running in a pseudo-terminal
Along with the library and utilities, improvements were made to the ncurses-examples:
modify test_tparm to account for extended
capabilities
corrected mouse mask in test/testcurs.c
modify test/clip_printw.c to optionally test
non-wrapped updates
modify test/test_mouse.c to use curses api
for raw/noraw
modify test/clip_printw.c to optionally test
non-wrapped updates
There is one new demo/test programs:
This program shows the return-status from
endwin with different combinations of
endwin (repeated), initscr,
newterm.
There are several new terminal descriptions:
linux+kbs for terminals which imitate xterm's behavior with Linux
vt100+noapp, vt100+noapp+pc, xterm+app+pc, xterm+decedit from xterm #389
putty+cursor to reflect amending of modified cursor-keys in 2021
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:
document XF, kxIN and kxOUT
add note on sun regarding wscons/cmdtool/shelltool
remove DECCOLM+DECSCLM from foot
add xterm+focus to foot+base
add ecma+strikeout to putty
use CSI 3J in vte-2017
use oldxterm+sm+1006 in vte-2014
modify xgterm to work around line-drawing bug
add xterm focus mode 1004 to xterm+focus as fe/fd capabilities, like vim.
add xterm+focus to alacritty+common
add XR/xr, to work with vim, and use RV/rv to denote DA2 and its response
add XF flag to xterm+focus so that termcap applications can be aware of terminals which may support focus in/out
use xterm+focus in xterm-p370 and tmux
remove xterm+sm+1006 from tmux
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:
add assignment in CF_MAN_PAGES to fill in
value for TERMINFO_DIRS in ncurses, terminfo
and tic manpages.
clarify interaction of -R option versus
-C, -I and -r in
infocmp manpage.
correct manpage description of panel_hidden.
improve manpage description for addch versus unctrl format used for non-printable characters.
improve manpages discussing file descriptors in low-level functions.
improve description of search rules for terminal descriptions in terminfo manpage.
modify dist.mk to avoid passing developer's comments in manpages into the generated html documentation.
modify test-package "ncurses6-doc" to use manpage-aliases, which in turn required a change to the configure script to factor in the extra-suffix option when deriving alias names.
New/improved history and portability sections:
add information about "ttycap", termcap's forerunner, to tset.1
document limitations of tparm, and error-returns in curs_terminfo.3x
document limitations of tgoto, and error-returns in curs_termcap.3x
Other improvements:
This release has many changes to improve the formatting and style of the manpages.
Manpages now use consistent section-naming, page headers and footers (including the modification date for each page).
Table layout has been revised.
There are no new manual pages (all of the manual page updates are to existing pages).
The changes to tparm, tgoto which improve the design of the low-level interfaces are interesting, but are not bug-fixes per se.
These are the major changes (aside from introducing tiparm_s):
use wide-character (ncursesw) by default
use opaque typedefs by default
However, most of the work on configure scripts was done to reduce warnings within the configure script:
intrusive warnings from GNU grep regarding fgrep and egrep
fatal errors in compile-checks, arising from recent “Modern C” efforts by some developers which caused longstanding configure checks to fail.
After repairing the configure script, none of that activity affected ncurses because stricter warnings are used routinely in development.
Other improvements made to configure checks include
use string-hacks in alloc_entry.c, alloc_type.c and hardscroll.c, overlooked due to compiler changes in recent OpenBSD releases
revise progs.priv.h to provide for NC_ISATTY reuse
configure check for MB_LEN_MAX provides warning as needed
trim a space after some "-R" options, fixing builds for applications built using clang and ncurses on Solaris
work around misconfiguration of MacPorts gcc13, which exposes invalid definition of MB_LEN_MAX in gcc's fallback copy of limits.h
modified experimental Windows driver works with xterm mouse protocol
There are a few new configure options:
Compile with environment restriction, so certain environment variables are not available when running via a setuid/setgid application. These are (for example $TERMINFO) those that allow the search path for the terminfo or termcap entry to be customized.
A setuid/setgid application inherits its environment variables from the current user, in contrast to sudo which may limit the environment variables that ncurses uses.
Compile-in feature to detect screensize for terminals which do not advertise their screensize, e.g., serial terminals.
Override the displayed (rather than compiled-in) ABI. Only packagers who have created configurations where the ABI differs from ncurses should be interested in this option.
When stripping executables during install, use the specified program rather than “strip” overriding program chosen by the install program for stripping executables.
These configure options are modified:
The optional DIR parameter can now be “auto” to automatically use pkg-config's library directory.
The default is $(libdir).
The default is “auto” which tells the configure script to choose BS or DEL according to platform defaults.
Many of the portability changes are implemented via the configure script:
add/use configure check for clock_gettime, to
supersede gettimeofday.
modify configure script check for pkg-config library directory to take into account an older version 0.15.0 which used PKG_CONFIG_PATH but not PKG_CONFIG_LIBDIR
allow for MinGW32-/64-bit configurations to use _DEFAULT_SOURCE
modify CF_XOPEN_SOURCE macro's amend default case to avoid undefining _XOPEN_SOURCE if _POSIX_C_SOURCE is defined
updated configure script macro CF_XOPEN_SOURCE, for uClibc-ng
modify version-check for gcc/g++, now works for msys2
build-fixes related to configure-options and/or platform:
other configure-script improvements:
Here are some of the other portability fixes:
modify configure scripts/makefiles to omit KEY_RESIZE if the corresponding SIGWINCH feature is disabled
increase MB_CUR_MAX to 16, matching glibc's MB_LEN_MAX
add BSD erase2 to characters handled by tset/reset
use getauxval when available, to improve setuid/setgid checks
set dwShareMode in calls to CreateConsoleScreenBuffer
use CreateFile with "CONIN$", "CONOUT$" rather than GetStdHandle to obtain a handle on the actual console, avoiding redirection in the MinGW/Win32 configurations
modify MinGW driver to return KEY_BACKSPACE when an unmodified VK_BACK virtual key is entered
modify MinGW configuration to provide for running in MSYS/MSYS2 shells, assuming ConPTY support
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, supporting a stack of windows with backing store
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
stdscr, andExcept 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).
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
- cdk
Curses Development Kit
- ded
directory-editor
- dialog
the underlying application used in Slackware's setup, and the basis for similar install/configure applications on many systems.
- lynx
the text WWW browser
- mutt
mail utility
- ncftp
file-transfer utility
- 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.
- tin
newsreader, supporting color, MIME
- vifm
File manager with vi like keybindings
as well as some that use ncurses for the terminfo support alone:
- minicom
terminal emulator for serial modem connections
- mosh
a replacement for
ssh.- tack
terminfo action checker
- tmux
terminal multiplexor
- vile
vi-like-emacs may be built to use the terminfo, termcap or curses interfaces.
and finally, those which use only the termcap interface:
- emacs
text editor
- less
The most commonly used pager (a program that displays text files).
- screen
terminal multiplexor
- vim
text editor
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
bug-ncurses@gnu.org
To join the ncurses mailing list, please write email to
bug-ncurses-request@gnu.orgcontaining 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/6.4/ and
https://invisible-mirror.net/archives/ncurses/6.4/ .
There is an archive of the mailing list here:
The release notes make scattered references to these pages, which may be interesting by themselves:
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.