# 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

containing the line:

> `subscribe` <name>@<host.domain>

This list is open to anyone interested in helping with the development and testing of this package.

Beta versions of ncurses 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 .