https://invisible-island.net/ncurses/

Announcing ncurses 6.1

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 OSX.
• 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:

ftp://ftp.invisible-island.net/ncurses/ or
https://invisible-mirror.net/archives/ncurses/ .

It is also available via anonymous FTP at the GNU distribution site

ftp://ftp.gnu.org/gnu/ncurses/ .

Release Notes

These notes are for ncurses 6.1, released January 27, 2018.

This release is designed to be source-compatible with ncurses 5.0 through 6.0; providing extensions to the application binary interface (ABI). Although the source can still be configured to support the ncurses 5 ABI, the intent of the release is to provide extensions to the ncurses 6 ABI:

• improve integration of tput and tset

• provide support for extended numeric capabilities.

There are, of course, numerous other improvements, listed in this announcement.

The release notes also mention some bug-fixes, but are focused on new features and improvements to existing features since ncurses 6.0 release.

Library improvements

New features

The improved integration of tput and tset made only small changes to the libraries. However, supporting extended numeric capabilities required a few changes:

• The TERMINAL structure in <term.h> is now opaque. Doing that allowed making the structure larger, to hold the extended numeric data.

  A few applications required changes during development of ncurses 6.1 because those applications misused the members of that structure, e.g., directly modifying it rather than using def_prog_mode.

• Having made TERMINAL opaque (and because none of the library functions use anything except a pointer to TERMINAL), it was possible to increase the size of the structure, adding to the end.

  Existing applications which were linked to the ncurses 6.0 high-level (ncurses, ncursesw) and low-level (tinfo, tinfo) libraries should not require re-linking since the binary interface did not change, nor did the structure offsets with TERMINAL change.

  A few applications use the inner TERMTYPE structure's offsets to refer to terminfo capabilities within that structure. Again, those do not require modification because their offsets within TERMINAL did not change.

• When configured for wide-characters, i.e., “ncursesw” the TERMINAL structure is extended.

  The new data in TERMINAL holds the same information as TERMTYPE, but with larger numbers (“int” versus “short”). It is named TERMTYPE2.

  The library uses this structure internally in preference to TERMTYPE, referring to TERMTYPE only to initialize it for applications that use the capabilities defined in <term.h>

• When configured for 8-bit (narrow) characters, the TERMTYPE2 structure is not used.

• The updated application binary interface is 6.1.20171230 (used for new versioned symbols), although the interface changes were developed several months previously.

The motivation for making this extension came from noticing that termcap applications could (though not realistically) use larger numbers than would fit in 16-bits, and the fact that the number of color pairs for a 256-color xterm could not be expressed in terminfo (i.e., 32767 versus 65536). Also, a few terminals support direct-colors, which could use the extension.

Generally speaking, applications that use internal details of a library are unsupported. There was exactly one exception for ncurses: the tack program used the internal details of TERMINAL, because it provides an ncurses-specific feature for interactively modifying a terminfo description and writing the updated description to a text-file. It was possible to not only separate tack from these internal details of ncurses, but to generalize it so that the program works with Unix curses (omitting the ncurses-specific feature). That was released as tack 1.08 in July 2017.

While making changes to tack to eliminate its dependency upon ncurses internals, the publicly-visible details of those internals were reviewed, and some symbols were moved to private header files, while others were marked explicitly as ncurses internals. Future releases of ncurses may eliminate some of those symbols (such as those used by tack 1.07) because they are neither part of the API or the ABI.

Using the TERMTYPE2 extended numeric capabilities, it is possible to support both color pair values and color values past 32767. Taking compatibility into account, developers readily understand that neither function signatures nor structure offsets change. Also, existing functions have to operate with the extended numbers. Most of that work is internal to the library. For the external interfaces, a hybrid approach was used:

• X/Open Curses defined function prototypes such as wattr_set with an unused parameter, for “future” use. After 25 years, the future is here: ncurses uses the parameter to augment color pair values as described in the manual page.

• Other functions such as those defining color pairs did not have a corresponding reserved parameter. For those, ncurses defines extended versions such as init_extended_pair (versus init_pair), init_extended_color (versus init_color).

Additionally, to improve performance other changes (and extensions) are provided in this release:

• Several new functions simplify management of large sets of color pairs: reset_color_pairs, alloc_pair, find_pair and free_pair.

• New "RGB" extension capability for direct-color support is used to improve performance of color_content.

• The internal colorpair_t is now a struct, eliminating an internal 8-bit limit on colors

• Allocation for SCREEN's color-pair table starts small, grows on demand up to the limit given in the terminal description.

• setcchar and getcchar now treat a negative color-pair as an error.

Other improvements

These are new or revised features:

• modify c++/etip.h.in to accommodate deprecation of throw and throws in c++17

• add new function unfocus_current_field

• add option to preserve leading whitespace in form fields

• add a macro for is_linetouched and adjust the function's return value to make it possible for most applications to check for an error-return.

• add build-time utility report_offsets to help show when the various configurations of tinfo library are compatible or not.

These were done to limit or ultimately deprecate features:

• drop two symbols obsoleted in 2004: _nc_check_termtype, and _nc_resolve_uses

• move _nc_tracebits, _tracedump and _tracemouse to curses.priv.h, since they are not part of the suggested ABI6.

• mark some structs in form/menu/panel libraries as potentially opaque without modifying API/ABI.

• ifdef'd header-file definition of mouse_trafo with NCURSES_NOMACROS

• remove initialization-check for calling napms in the term-driver configuration; none is needed.

• modify trace to avoid overwriting existing file

These are improvements to existing features:

• modify make_hash to allow building with address-sanitizer, assuming that --disable-leaks is configured.

• move SCREEN field for use_tioctl data before the ncursesw fields, and limit that to the sp-funcs configuration to improve termlib compatibility

• modify db-iterator:

  • ignore zero-length files in db-iterator; these are useful for instance to suppress $HOME/.terminfo when not wanted.

  • modify update_getenv to ensure that environment variables which are not initially set will be checked later if an application happens to set them

• modify _nc_outc_wrapper to use the standard output if the screen was not initialized, rather than returning an error.

• improve checks for low-level terminfo functions when the terminal has not been initialized.

• modify set_curterm to update ttytype[] data used by longname/p>

• modify _nc_get_screensize to allow for use_env and use_tioctl state to be per-screen when sp-funcs are configured, better matching the behavior when using the term-driver configuration.

• remove an early-return from _nc_do_color, which can interfere with data needed by bkgd when ncurses is configured with extended colors

• incorporate A_COLOR mask into COLOR_PAIR, in case user application provides an out-of-range pair number

• modify logic for endwin-state to be able to detect the case where the screen was never initialized, using that to trigger a flush of ncurses' buffer for mvcur, e.g., in the sample program dots_mvcur for the term-driver configuration.

These are corrections to existing features:

• fixes for writing extended color pairs in putwin.

• modify no-leaks code for lib_cur_term.c to account for the tgetent cache.

• amend handling of the repeat_char capability in EmitRange to avoid scope creep: translate the character to the alternate character set when the alternate character set is enabled, and do not use repeat_char for characters past 255.

• improve wide-character implementation of myADDNSTR in frm_driver.c, which was inconsistent with the normal implementation.

• modify winnstr and winchnstr to return error if the output pointer is null, as well as adding a null pointer check of the window pointer for better compatibility with other implementations.

• modify setupterm to save original tty-modes so that erasechar works as expected. Also modify _nc_setupscreen to avoid redundant calls to get original tty-modes.

• modify wattr_set and wattr_get to return ERR if win-parameter is null, as documented.

• correct order of initialization for traces in use_env and use_tioctl versus first _tracef calls.

• correct parameters for copywin call in _nc_Synchronize_Attributes

• flush the standard output in _nc_flush for the case where SP is zero, e.g., when called via putp. This fixes a scenario where “tput flash” did not work after changes in 20130112.

• amend internal use of tputs to consistently use the number of lines affected, e.g., for insert/delete character operations. While merging terminfo source early in 1995, several descriptions used the “*” proportional delay for these operations, prompting a change in doupdate.

• correct return-value of extended putwin.

• double-width multibyte characters were not counted properly in winsnstr and wins_nwstr.

• amend fix for _nc_ripoffline from 20091031 to make test/ditto.c work in threaded configuration.

• modify _nc_viscbuf2 and _tracecchar_t2 to trace wide-characters as a whole rather than their multibyte equivalents.

• minor fix in wadd_wchnstr to ensure that each cell has nonzero width.

• move PUTC_INIT calls next to wcrtomb calls, to avoid carry-over of error status when processing Unicode values which are not mapped.

• add missing assignment in lib_getch.c to make notimeout work

Program improvements

While reviewing user feedback, it became apparent that the differences between reset (an alias for tset) and “tput reset” were confusing:

• one (tset) updated the terminal modes, but used only part of the terminfo capabilities for initialization, while
• the other (tput) used all of the terminal capabilities while neglecting the terminal modes.

On further investigation, it turned out that the differences were largely an accident due to the way those programs had evolved.

This release eliminates the unnecessary differences, using the same approach for tput's init (initialization), reset and clear operations as the separate reset and clear programs. Doing this does not change the command-line options; existing scripts are unaffected.

These are the user-visible changes for the three programs (tput, tset and clear):

• add the terminal-mode parts of “reset” (aka tset) to the “tput reset” command, making the two almost the same except for window-size.

• improve tput's check for being called as “init” or “reset” to allow for transformed names.

• add “clear” as a possible link/alias to tput.

• amend changes for tput to reset tty modes to “sane” if the program is run as “reset”, like tset. Likewise, ensure that tset sends either reset- or init-strings.

• add -x option to clear/tput to make the E3 extension optional

• add functionality of “tset -w” to tput, like the “-c” feature this is not optional in tput.

• add options -T and -V to clear command for compatibility with tput.

• drop long-obsolete “-n” option from tset.

• modify tset's assignment to TERM in its output to reflect the name by which the terminal description is found, rather than the primary name. That was an unnecessary part from the initial conversion of tset from termcap to terminfo. The termcap library in 4.3BSD did this to avoid using the short 2-character name

• remove a restriction in tput's support for termcap names which omitted capabilities normally not shown in termcap translations

• add usage message to clear command

• improve usage messages for tset and tput.

Other user-visible improvements and new features include:

• modify tic/infocmp display of numeric values to use hexadecimal when they are "close" to a power of two, making the result more readable.

• add “-W” option to tic/infocmp to force long strings to wrap.

  • This is in addition to the “-w” option which attempts to fit capabilities into a given line-length.

  • If “-f” option splits line, do not further split it with “-W”.

  • Begin a new line when adding “use=” after a wrapped line.

• add “-q” option to infocmp to suppress the “Reconstructed from” comment from the header, and a corresponding option to tic to suppress all comments from the “tic -I” output.

• Sorted options in usage message for infocmp, to make it simpler to see unused letters.

• Updated usage message for tic, adding “-0” option.

• add infocmp/tic “-Q” option, which allows one to dump the compiled form of the terminal entry, in hexadecimal or base64:

  • A “b64:” prefix in the TERMINFO variable tells the terminfo reader to use base64 according to RFC-3548 as well as RFC-4648 url/filename-safe format.
  • A “hex:” prefix tells the terminfo reader to accept hexadecimal data as generated by “infocmp -0qQ1”.

Other less-visible improvements and new features include:

• modify utility headers such as tic.h to make it clearer which are externals that are used by tack.

• add “reset” to list of programs whose names might change in manpages due to program-transformation configure options.

• modify “-T” option of clear and tput to call use_tioctl to obtain the operating system's notion of the screensize if possible.

• add check in tput for init/reset operands to ensure those use a terminal.

• modify programs clear, tabs, tput and tset to pass the actual tty file descriptor to setupterm rather than the standard output or error, making padding work.

• change tset's initialization to allow it to get settings from the standard input as well as /dev/tty, to be more effective when output or error are redirected.

• amend check in tput, tabs and clear to allow those to use the database-only features in cron if a “-T” option gives a suitable terminal name.

• improve error message from tset/reset when both stderr/stdout are redirected to a file or pipe.

Several of the less apparent features deal with translation of terminfo to termcap (and the reverse), with corresponding checks by tic:

• modify check in fmt_entry to handle a cancelled reset string. Make similar fixes in other parts of dump_entry.c and tput.c

• correct read of terminfo entry in which all strings are absent or explicitly cancelled. Before this fix, the result was that all were treated as only absent.

• modify infocmp to suppress mixture of absent/cancelled capabilities that would only show as “NULL, NULL”, unless the “-q” option is used, e.g., to show “-, @” or “@, -”.

• correct a warning from tic about keys which are the same, to skip over missing/cancelled values.

• add check in tic for use of bold, etc., video attributes in the color capabilities, accounting whether the feature is listed in ncv.

• add check in tic for unnecessary use of “2” to denote a shifted special key.

• improve check in tic for delays by also warning about beep/flash when a delay is not embedded, or if those use the VT100 reverse video escape without using a delay.

• improve checks in trim_sgr0, comp_parse.c and parse_entry.c, for cancelled string capabilities.

• add check in tic for some syntax errors of delays, as well as use of proportional delays for non-line capabilities.

• add check in tic for conflict between ritm, rmso, rmul versus sgr0.

• add check in _nc_parse_entry for invalid entry name, setting the name to “invalid” to avoid problems storing entries.

• improve _nc_tparm_analyze, using that to extend the checks made by tic for reporting inconsistencies between the expected number of parameters for a capability and the actual.

• remove tic warning about “^?” in string capabilities, which was marked as an extension; however all Unix implementations support this and X/Open Curses does not address it. On the other hand, BSD termcap did not support this feature (until the mid-1990s).

  in _nc_infotocap, added a check to ensure that terminfo “^?” is not written to termcap.

• modify sscanf calls in _nc_infotocap for patterns “%{number}%+%c” and “%'char'%+%c” to check that the final character is really “c”, avoiding a case in icl6404 which cannot be converted to termcap.

• in _nc_tic_expand and _nc_infotocap, improved string-length check when deciding whether to use “^X” or “\xxx” format for control characters, to make the output of tic/infocmp more predictable.

• limited termcap “%d” width to 2 digits on input, and use “%2” in preference to “%02” on output.

• correct terminfo/termcap conversion of “%02” and “%03” into “%2” and “%3”; the result repeated the last character.

Examples

Along with the library and utilities, many improvements were made to the ncurses-examples.

These changes were made to demonstrate new extensions in ncurses:

• add demo_new_pair program, to demonstrate alloc_pair, find_pair and free_pair functions.

  This program iterates over the possible color combinations, allocating or initializing color pairs. For best results, choose screen-width dividing evenly into the number of colors. e.g.,

  32x64,32x128	256 colors
  24x44,24x88	88 colors
  32x64,24x128	16 colors

• add extended_color program, like the older color_set program, but using the extended color functions, with and without the SP-functions interface.

• add picsmap program to fill in some testing issues not met by dots, using this as the third example in a comparison of the ncurses versus slang libraries.

  The program can directly read X bitmap and pixmap files, displaying a picture. It can read other image files using ImageMagick's convert program to translate the image into text.

  For 16-, 88- and 256-color terminal descriptions, picsmap can load a palette file which tells it which color palette entries to use. For direct-colors, the terminal descriptions use the RGB extension capability.

There are other new example programs and a few scripts:

• add dots_xcurses program to illustrate a different approach used for extended colors which can be contrasted with dots_curses.

• add list_keys program show function keys for one or more terminal descriptions. It uses ncurses's convention of modifiers for special keys, based on xterm.

• add padview program, to compare pads with direct updates in the view program.

• add sp_tinfo program to exercise the SP-functions extension of the low-level terminfo library.

• add test-programs for termattrs and term_attrs functions.

• add test_sgr program to exercise all combinations of the sgr capability.

• add tput-colorcube demo script, imitating xterm's 88- and 256-color scripts using tput.

• add tput-initc script to demonstrate how tput may be used to initialize a color palette from a data file.

A variety of improvements were made to existing programs, both new features as well as options added to make the set of programs more consistent.

The ncurses program is the largest; a proportionately large number of changes were made to it:

• modify a/A screens to make exiting on an escape character depend on the start of keypad and timeout modes, to allow better testing of function-keys.

  add “t” toggle for notimeout function.

• modify layout of b/B screens to allow for additional annotation on the right margin; some terminals with partial support did not display well.

• modify c/C screens to allow for extended color pairs.

  add z/Z zoom feature to make extended color pairs easier to test.

  modify test-screens to take advantage of wide screens, reducing the number of lines used for 88- and 256-colors.

• modify “d” edit-color screen to optionally read xterm color palette directly from terminal, as well as handling KEY_RESIZE and screen-repainting with control/L and control/R.

• add examples to “F” screen for WACS_D_PLUS and WACS_T_PLUS.

• improve “g” screen, correcting ifdef which made the legend not reflect changes to keypad- and scroll-modes. Added check for return-value of putwin.

• make “s” test easier to understand which subtests are available

  add a corresponding “S” wide-character overlap test-screen.

• add “v” screen to show baudrate and other values.

These changes were made to the other examples:

• modify blue program to use Unicode values for card-glyphs when available, as well as improving the check for CP437 and CP850.

• improve demo_menus program, allowing mouse-click on the menu-headers to switch the active menu. This requires a new extension option O_MOUSE_MENU to tell the menu driver to put mouse events which do not apply to the active menu back into the queue so that the application can handle the event.

• correct logic in demo_terminfo program for “-f” option

• modify ditto program to allow $XTERM_PROG environment variable to override "xterm" as the name of the program to run in the threaded configuration.

• add several options to the “dots” test-programs.

• modify filter program:

  • illustrate an alternative to getnstr, that polls for input while updating a clock on the right margin as well as responding to window size-changes.
  • adapt logic used in dialog “--keep-tite” option for filter program as the "-a" option. When set, filter attempts to suppress the alternate screen.

• modify knight program to provide the "slow" solution for small screens using “R”, noting that Warnsdorf's method is easily done with “a”.

• modify the savescreen program to add test patterns that exercise 88-, 256-, etc., colors.

• add options to test_arrays, for selecting termcap vs terminfo, etc.

• modify the view program:

  • expand tabs using the ncurses library rather than in the test-program.
  • eliminate the “-n” option by simply reading the whole file.
  • implement page up/down commands.
  • remove the very old SIGWINCH example; just use KEY_RESIZE.

• improve animation in xmas program by adding a time-delay in blinkit.

• modify several test-programs which call use_default_colors to consistently do this only if the “-d” option is given.

• modify the install-rule for ncurses-examples to put the data files in the data directory, e.g., /usr/share/ncurses-examples.

• modify several test programs to use new popup_msgs function, adapted from the help-screen used in the edit_field program.

• modify test data for xterm palettes to use the newer color4/color12 values.

• improve the tracemunch script:

  • show screenXX pointers and thread identifiers as names.
  • chang address-parameters of add_wch, color_content and pair_content to dummy parameters.

Terminal database

There are several new terminal descriptions:

dumb-emacs-ansi, dvtm, dvtm-256color, fbterm, iterm2, linux-m1 minitel entries, putty-noapp, viewdata, and vt100+4bsd building-block.

xterm+noalt, xterm+titlestack, xterm+alt1049, xterm+alt+title building blocks and xterm+direct, xterm+indirect, xterm-direct. from xterm patch #331.

several other “-direct” descriptions to address the differences of other terminal emulators versus xterm-direct.

There are many changes to existing terminal descriptions. Some were updates to several descriptions:

• use xterm+sm+1006 in several terminal descriptions which were validated as supporting the extended mouse feature for their respective terminal emulators.
• corrected sgr/sgr0 strings in a few cases reported by tic, making those correspond to the non-sgr settings where they differ, but otherwise use ECMA-48 consistently.
• add 0.1sec mandatory delay to flash capabilities using the VT100 reverse-video control

while others affected specific descriptions. These were retested, to take into account new/undocumented changes by their developers:

iterm, minitel, st, viewdata, nsterm

while these are specific fixes based on user reports, or warnings from tic:

ansi building blocks

• restored rmir/smir in ansi+idc to better match original ansiterm+idc, add alias ansiterm

icl6402

• corrected missing comma-separator between string capabilities in icl6402 and m2-nam

interix

• updated using tack and SFU with Windows 7 Ultimate.
• used ^? for kdch1

linux

• made linux3.0 entry the default linux entry
• modify linux2.6 entry to improve line-drawing so that the linux3.0 entry can be used in non-UTF-8 mode
• omitted selection of ISO-8859-1 for G0 in enacs capability from linux2.6 entry, to avoid conflict with the user-defined mapping. The reset feature uses ISO-8859-1 in any case.
• modify flash capability for linux and wyse entries to put the delay between the reverse/normal escapes rather than after
• modify linux-16color to not mask dim, standout or reverse with the ncv capability

pccon entries

• fixed some inconsistencies in the pccon* entries
• add bold to pccon+sgr+acs and pccon-base
• add keys f12-f124 to pccon+keys

tmux

• corrected sgr string, which used screen's "standout" code rather than the standard code.
• add settings corresponding to xterm-keys option to reflect upcoming change to make that option "on" by default
• uncanceled Ms

vt100

• modify vt100 rs2 string to reset vt52 mode and scrolling regions
• corrected rs2 string for vt100-nam
• made minor fixes for vt100+4bsd, e.g., delay in sgr for consistency

vte

• moved SGR 24 and 27 from vte-2014 to vte-2012
• add a few capabilities fixed in recent VTE development

xterm

• add rep to xterm-new, available since late 1996.
• modify xterm+256color and xterm+256setaf to use correct number of color pairs.
• modify rs1 for xterm-16color, xterm-88color and xterm-256color to reset palette using oc string as in linux entry.
• add rs1 capability to xterm-256color
• add oc capability to xterm+256color, allowing palette reset for xterm
• add op to xterm+256setaf
• modify xterm-r5, xterm-r6 and xterm-xf86-v32 to use xterm+kbs to match xterm #272, reflecting packager's changes
• used ANSI reply for u8 in xterm-new, to reflect vt220-style responses that could be returned.
• made xterm-pcolor sgr consistent with other capabilities

A few entries use extensions (user-defined terminal capabilities):

• add rmxx/smxx ECMA-48 strikeout extension to tmux and xterm-basic
• used RGB capability in new *-direct entries to denote direct-color feature.

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 particular,

• Since the underlying features for tset, tput, and clear have been better integrated, the documentation now includes information on how those tools evolved.

  In addition to explaining the improved integration of the tools, the manual pages made it easier to see how the tools are similar and how they are different.

• The addch manual page has additional information on portability and differences from other implementations.

• The discussion of color-pairs in the attributes manual page is improved in its history section.

• The documentation of the chtype, cchar_t types and the attribute values which can be stored in those types, in particular the history and portability sections of the attributes manual page, has been improved.

• improve discussion of portability in the mouse manual.

• The pad manual page has a section on the origin and portability of pads.

• Differences between SVr4 and X/Open Curses soft-keys are discussed in a new section on portability.

• There are updated/improved notes on portability in the resizeterm and wresize manual pages.

In addition to providing background information to explain these features and show how they evolved, there are corrections, clarifications, etc.:

• add note in the addch manual about line-drawing when it depends upon UTF-8.

• improve discussion of line-drawing characters in the add_wch manual.

• explain in clear's manual page that it writes to the standard output.

• improve description of endwin.

• improve discussion of field validation in the form driver manual page.

• clarify the use of wint_t vs wchar_t in get_wstr manual page.

• clarify in the getch manual that the keypad mode affects an application's ability to read KEY_MOUSE codes, but does not affect KEY_RESIZE.

  trim some obsolete/incorrect wording about EINTR from the getch manual page

  improve manual pages for getch and get_wch to point out that they might return user-defined values which have no predefined names in <curses.h>

• improve description of the -R option in the infocmp manual page

• clarify in the resizeterm manual page how KEY_RESIZE is pushed onto the input stream.

• document return value of use_extended_names

• document differences in ESCDELAY versus AIX's implementation in the variables manual page.

• The _nc_free_tinfo function is now documented in the memory-leaks manual page, because it could be used in tack for memory-leak checking.

• add a note to the tic manual page about -W versus -f options.

• improve terminfo manual description of terminfo syntax.

  improve terminfo manual page discussion of control- and graphics- characters.

  improve color-handling section in terminfo manual page

• clarify description in tput manual page regarding support for termcap names

  update tput manual page to reflect changes to manipulate terminal modes by sharing functions with tset.

• clarify in manual pages that the optional verbose option level of tic and infocmp is available only when ncurses is configured for tracing.

• improve manual page description of tset/reset versus window-size.

• improve description of tgoto parameters

There are new manual pages:

• user_caps documents the terminfo extensions used by ncurses.

• scr_dump documents the screen-dump format.

Some of the improvements are more subtle, relating to the way the information is presented:

• Made minor fixes to manpage NAME/SYNOPSIS sections to consistently use rule that either all functions which are prototyped in SYNOPSIS are listed in the NAME section, or the manual-page name is the sole item listed in the NAME section. The latter is used to reduce clutter, e.g., for the top-level library manual pages as well as for certain feature-pages such as SP-funcs and threading.

• improve manual pages for utilities with respect to POSIX versus X/Open Curses.

• improve organization of the attributes and color manual pages.

Interesting bug-fixes

• modify toe to not exit if unable to read a terminal description, e.g., if there is a permission problem.

• correct 20100515 change for weak signals versus sigprocmask

• work around Ada tool-breakage in Debian 9 and later by invoking gprconfig to specify the C compiler to be used by gnatmake, and conditionally suppressing Library_Options line for static libraries.

• There were, as well, several bug-fixes to handle illegal input for tic. Because those did not correspond to useful terminal descriptions, most users are unaffected.

Configuration changes

Major changes

This release provides a new binary format for terminal descriptions that use extended numeric capabilities. Applications built with the wide-character ncursesw library can use these extended numbers.

• This includes utilities such as tic and infocmp, because (as noted in New features), the feature relies upon an extension to the low-level tinfo library.

• A few software packagers use a configuration option of ncurses which allows the low-level tinfo library to be shared between the high-level ncurses and ncursesw libraries. This new feature was designed to work in that configuration as well.

Other applications (i.e., using the 8-bit ncurses library) which read the extended terminal descriptions see those numeric capabilities set to the maximum value for a signed 16-bit number.

Older versions of ncurses' tic accept out-of-range numeric capabilities, storing those as the maximum value for a signed 16-bit number. Other implementations of curses (mentioned in the discussion of picsmap) give zero for these out-of-range capabilities.

Configuration options

These changes provide support for tack 1.08, released in July 2017:

• add --without-tack configure option to refine --with-progs configure option. Normally tack is built outside the ncurses tree, but a few packagers combine it during the build. If term_entry.h is installed, there is no advantage to in-tree builds.

• adjust configure-script to define HAVE_CURSES_DATA_BOOLNAMES symbol needed for tack 1.08 when built in-tree. Rather than relying upon internal "_nc_" functions, tack now uses the boolean, number and string capability name-arrays provided by ncurses and SVr4 Unix curses. It still uses term_entry.h for the definitions of the extended capability arrays.

• add dependency upon ncurses_cfg.h to tic's header-files; any program using tic-library will have to supply this file. Legacy tack versions supply this file; ongoing tack development has dropped the dependency upon tic-library and new releases will not be affected.

Other changes to the configure-script and generated files include

• add configure options to disable checks for form, menu and panel libraries so that ncurses-examples can be built with non-SVr4 curses implementations.

• add configure option --enable-opaque-curses for ncurses library and similar options for the other libraries.

• add configure option --disable-wattr-macros for use in cases where one wants to use the same headers for ncurses5/ncurses6 development, by suppressing the wattr* macros which differ due to the introduction of extended colors

• modify configure macro for shared-library rules to use -Wl,-rpath rather than -rpath to work around a bug in scons

• improve ncurses-examples' configure script to define as needed NCURSES_WIDECHAR for platforms where _XOPEN_SOURCE_EXTENDED does not work. Also modified the test program to ensure that if building with ncurses, that the cchar_t type is checked, since that is normally (since 20111030) ifdef'd depending on this test.

• modify configure script to handle the case where tic-library is renamed, but the --with-debug option is used by itself without normal or shared libraries

• modify editing script which generates resulting.map to work with the clang configuration on recent FreeBSD, which gives an error on an empty "local" section.

• improve configure check for setting the WILDCARD_SYMS variable; on ppc64 the variable is in the Data section rather than Text.

• correct result of configure option --without-fallbacks, which caused FALLBACK_LIST to be set to "no"

• modify --with-pkg-config-libdir option to make it possible to install “.pc” files even if pkg-config is not found. Limit this change, to suppress the actual install if it is not overridden to a valid directory at install time.

• disallow “no” as a possible value for --with-shlib-version option, overlooked in cleanup-changes for 20000708.

Portability

Many of the portability changes are implemented via the configure script:

• improve configure script's CF_CC_ENV_FLAGS macro to allow for compiler wrappers such as ccache. This change moves only the preprocessor, optimization and warning flags to CPPFLAGS and CFLAGS, leaving the residue in CC. That happens to work for gcc's various “model” options, but may require tuning for other compilers.

• modify ncurses-examples' configure script to use pkg-config for the extra form/menu/panel libraries, to be more consistent with the handling of the curses/ncurses library.

• add configuration checks to build with NetBSD curses, which for example lacks use_env.

• change ncurses-examples to use attr_t vs chtype to follow X/Open documentation more closely since Solaris xpg4-curses uses different values for WA_xxx vs A_xxx that rely on attr_t being an unsigned short. Tru64 aka OSF1, HPUX, AIX did as ncurses does, equating the two sets.

• modify several test programs to reflect that ncurses honors existing signal handlers in initscr, while other implementations do not.

• add configure check for openpty to ncurses-examples' configure script, for ditto.

• improve check for working poll function by using posix_openpt as a fallback in case there is no valid terminal on the standard input

• modify ncurses-examples' configure script to check for pthread dependency of ncursest or ncursestw library when building the ncurses examples, e.g., in case weak symbols are used.

• add checks in ncurses-examples' configure script for some functions neither in 4.3BSD curses, nor based on X/Open Curses:

  • modify a loop limit in firework.c to work around absense of limit checks in some libraries.

  • fill the last row of a window with “?” in firstlast if waddch does not return ERR on the lower-right corner.

• build-fixes for the Portland Group (PGI) compilers

  • accept whitespace in sed expression for generating expanded.c

  • modify configure check that g++ compiler warnings are not used.

  • add configure check for -fPIC option needed for shared libraries.

• modify configure script for clang as used on FreeBSD, to work around clang's differences in exit codes vs gcc.

• fixes for configure/build using clang on OSX

  • do not redefine “inline” in ncurses_cfg.h; this was originally to solve a problem with gcc/g++, but is aggravated by clang's misuse of symbols to pretend it is gcc.

  • add braces to configure script to prevent unwanted addition of “-lstdc++” option to the CXXLIBS symbol.

  • improve/update test-program used for checking existence of stdc++ library.

  • if $CXXLIBS is set, the linkage test uses that in addition to $LIBS.

• fixes for OS/2:

  • use button instead of kbuf[0] in EMX-specific part of lib_mouse.c

  • support building with libtool on OS/2

  • use stdc++ library with OS/2 kLIBC

  • clear configure script's cf_XOPEN_SOURCE for OS/2, to work with its header files

• add “newer” baudrate symbols to the baudrate function in the ncurses library as well as to a corresponding table in tset.

• modify ncurses-examples savescreen to work with AIX and HPUX.

• define WIN32_LEAN_AND_MEAN for MinGW port, making builds faster.

• add a configure check for wcwidth versus the ncurses line-drawing characters, to use in special-casing systems such as Solaris. Solaris, however, requires a special case that maps Unicode line-drawing characters into the acsc string for non-Unicode locales. Solaris also has a misconfigured wcwidth which marks all of the line drawing characters as double-width.

• string-hacks (non-standard):

  • fix configure script to record when strlcat is found on OpenBSD.

  • add --enable-string-hacks option to ncurses-examples' configure script.

  • completed string-hacks for sprintf, etc., including the ncurses-examples programs.

  • make --enable-string-hacks option work with Debian by checking for the "bsd" library and its associated "<bsd/string.h>" header.

• workaround for Debian's antique/unmaintained version of mawk:

  • see Debian #65617, which was fixed in mawk's upstream releases in 2009.

  • related fixes when building link_test.

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 Curses):

  • the panels library, supporting a stack of windows with backing store.

  • the menus 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 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 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 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 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 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.

• 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 #undef.

• 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/vi

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://alioth.debian.org/projects/minicom/

mosh

a replacement for ssh.

https://mosh.mit.edu/

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 Dickey. Thomas Dickey also acts as the maintainer for the Free Software Foundation, which holds the copyright on ncurses.

Contact the current maintainers at

bug-ncurses@gnu.org

To join the ncurses mailing list, please write email to

bug-ncurses-request@gnu.org

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 and patches to the current release are made available at

ftp://ftp.invisible-island.net/ncurses/ and
https://invisible-mirror.net/archives/ncurses/ .

There is an archive of the mailing list here:

http://lists.gnu.org/archive/html/bug-ncurses (also https)

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)
• 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 specification.

You can find lots of information on terminal-related topics not covered in the terminfo file at Richard Shuford's archive .