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NAME |SYNOPSIS |DESCRIPTION |VIDEO ATTRIBUTES |NOTES |HISTORY |EXTENSIONS |PORTABILITY |RETURN VALUE |SEE ALSO |COLOPHON | |
curs_attr(3X)curs_attr(3X)attr_get,wattr_get,attr_set,wattr_set,attr_off,wattr_off,attr_on,wattr_on,attroff,wattroff,attron,wattron,attrset,wattrset,chgat,wchgat,mvchgat,mvwchgat,color_set,wcolor_set,standend,wstandend,standout,wstandout-cursescharacter and window attribute control routines
#include <curses.h>int attr_get(attr_t *attrs, short *pair, void *opts);int wattr_get(WINDOW *win, attr_t *attrs, short *pair, void*opts);int attr_set(attr_tattrs, shortpair, void *opts);int wattr_set(WINDOW *win, attr_tattrs, shortpair, void *opts);int attr_off(attr_tattrs, void *opts);int wattr_off(WINDOW *win, attr_tattrs, void *opts);int attr_on(attr_tattrs, void *opts);int wattr_on(WINDOW *win, attr_tattrs, void *opts);int attroff(intattrs);int wattroff(WINDOW *win, intattrs);int attron(intattrs);int wattron(WINDOW *win, intattrs);int attrset(intattrs);int wattrset(WINDOW *win, intattrs);int chgat(intn, attr_tattr, shortpair, const void *opts);int wchgat(WINDOW *win,intn, attr_tattr, shortpair, const void *opts);int mvchgat(inty, intx,intn, attr_tattr, shortpair, const void *opts);int mvwchgat(WINDOW *win, int y, int x,intn,attr_tattr, shortpair, const void *opts);int color_set(shortpair, void*opts);int wcolor_set(WINDOW *win, shortpair, void*opts);int standend(void);int wstandend(WINDOW *win);int standout(void);int wstandout(WINDOW *win);
These routines manipulate the current attributes of the named win‐ dow, which then apply to all characters that are written into the window withwaddch,waddstrandwprintw. Attributes are a proper‐ ty of the character, and move with the character through any scrolling and insert/delete line/character operations. To the ex‐ tent possible, they are displayed as appropriate modifications to the graphic rendition of characters put on the screen. These routines do not affect the attributes used when erasing por‐ tions of the window. Seecurs_bkgd(3X) for functions which modify the attributes used for erasing and clearing. Routines which do not have aWINDOW*parameter apply tostdscr. For example,attr_setis thestdscrvariant ofwattr_set.Window attributes There are two sets of functions: • functions for manipulating the window attributes and color:wattr_setandwattr_get. • functions for manipulating only the window attributes (not color):wattr_onandwattr_off. Thewattr_setfunction sets the current attributes of the given window toattrs, with color specified bypair. Usewattr_getto retrieve attributes for the given window. Useattr_onandwattr_onto turn on window attributes, i.e., val‐ ues OR'd together inattr, without affecting other attributes. Useattr_offandwattr_offto turn off window attributes, again values OR'd together inattr, without affecting other attributes.Legacy window attributes The X/Open window attribute routines whichset orget, turnon oroff are extensions of older routines which assume that color pairs are OR'd into the attribute parameter. These newer routines use similar names, because X/Open simply added an underscore (_) for the newer names. Theintdatatype used in the legacy routines is treated as if it is the same size aschtype(used byaddch(3X)). It holds the com‐ mon video attributes (such as bold, reverse), as well as a few bits for color. Those bits correspond to theA_COLORsymbol. TheCOLOR_PAIRmacro provides a value which can be OR'd into the at‐ tribute parameter. For example, as long as that value fits into theA_COLORmask, then these calls produce similar results: attrset(A_BOLD | COLOR_PAIR(pair)); attr_set(A_BOLD,pair, NULL); However, if the value does not fit, then theCOLOR_PAIRmacro uses only the bits that fit. For example, because in ncursesA_COLOR has eight (8) bits, thenCOLOR_PAIR(259)is 4 (i.e., 259 is 4 more than the limit 255). ThePAIR_NUMBERmacro extracts a pair number from anint(orchtype). For example, theinput andoutput values in these state‐ ments would be the same: int value = A_BOLD | COLOR_PAIR(input); intoutput = PAIR_NUMBER(value); Theattrsetroutine is a legacy feature predating SVr4 curses but kept in X/Open Curses for the same reason that SVr4 curses kept it: compatibility. The remainingattr* functions operate exactly like the correspond‐ ingattr_* functions, except that they take arguments of typeint rather thanattr_t. There is no correspondingattrgetfunction as such in X/Open Curs‐ es, although ncurses providesgetattrs(see curs_legacy(3X)).Change character rendition The routinechgatchanges the attributes of a given number of characters starting at the current cursor location ofstdscr. It does not update the cursor and does not perform wrapping. A char‐ acter count of -1 or greater than the remaining window width means to change attributes all the way to the end of the current line. Thewchgatfunction generalizes this to any window; themvwchgat function does a cursor move before acting. In these functions, the colorpair argument is a color-pair index (as in the first argument ofinit_pair, seecurs_color(3X)).Change window color The routinecolor_setsets the current color of the given window to the foreground/background combination described by the colorpair parameter.Standout The routinestandoutis the same asattron(A_STANDOUT). The rou‐ tinestandendis the same asattrset(A_NORMAL)orattrset(0), that is, it turns off all attributes. X/Open does not mark these “restricted”, because • they have well established legacy use, and • there is no ambiguity about the way the attributes might be combined with a color pair.
The following video attributes, defined in<curses.h>, can be passed to the routinesattron,attroff, andattrset, or OR'd with the characters passed toaddch(seecurs_addch(3X)).Name Description ─────────────────────────────────────────────────────────────────A_NORMALNormal display (no highlight)A_STANDOUTBest highlighting mode of the terminal.A_UNDERLINEUnderliningA_REVERSEReverse videoA_BLINKBlinkingA_DIMHalf brightA_BOLDExtra bright or boldA_PROTECTProtected modeA_INVISInvisible or blank modeA_ALTCHARSETAlternate character setA_ITALICItalics (non-X/Open extension)A_CHARTEXTBit-mask to extract a characterA_COLORBit-mask to extract a color (legacy routines) These video attributes are supported byattr_onand related func‐ tions (which also support the attributes recognized byattron, etc.):Name Description ─────────────────────────────────────────WA_HORIZONTALHorizontal highlightWA_LEFTLeft highlightWA_LOWLow highlightWA_RIGHTRight highlightWA_TOPTop highlightWA_VERTICALVertical highlight The return values of many of these routines are not meaningful (they are implemented as macro-expanded assignments and simply re‐ turn their argument). The SVr4 manual page claims (falsely) that these routines always return1.
These functions may be macros:attroff,wattroff,attron,wattron,attrset,wattrset,standendandstandout. Color pair values can only be OR'd with attributes if the pair number is less than 256. The alternate functions such ascol‐or_setcan pass a color pair value directly. However, ncurses ABI 4 and 5 simply OR this value within the alternate functions. You must use ncurses ABI 6 to support more than 256 color pairs.
X/Open Curses is largely based on SVr4 curses, adding support for “wide-characters” (not specific to Unicode). Some of the X/Open differences from SVr4 curses address the way video attributes can be applied to wide-characters. But aside from that,attrsetandattr_setare similar. SVr4 curses provided the basic features for manipulating video attributes. However, earlier versions of curs‐ es provided a part of these features. As seen in 2.8BSD, curses assumed 7-bit characters, using the eighth bit of a byte to represent thestandout feature (often im‐ plemented as bold and/or reverse video). The BSD curses library provided functionsstandoutandstandendwhich were carried along into X/Open Curses due to their pervasive use in legacy applica‐ tions. Some terminals in the 1980s could support a variety of video at‐ tributes, although the BSD curses library could do nothing with those. System V (1983) provided an improved curses library. It defined theA_symbols for use by applications to manipulate the other attributes. There are few useful references for the chronology. Goodheart's bookUNIX Curses Explained (1991) describes SVr3 (1987), commenting on several functions: • theattron,attroff,attrsetfunctions (and most of the func‐ tions found in SVr4 but not in BSD curses) were introduced by System V, • the alternate character set feature withA_ALTCHARSETwas added in SVr2 and improved in SVr3 (by addingacs_map[]), •start_colorand related color-functions were introduced by System V.3.2, • pads, soft-keys were added in SVr3, and Goodheart did not mention the background character or thecchar_t type. Those are respectively SVr4 and X/Open features. He did mention theA_constants, but did not indicate their values. Those were not the same in different systems, even for those marked as System V. Different Unix systems used different sizes for the bit-fields inchtypeforcharacters andcolors, and took into account the dif‐ ferent integer sizes (32-bit versus 64-bit). This table showing the number of bits forA_COLORandA_CHARTEXT was gleaned from the curses header files for various operating systems and architectures. The inferred architecture and notes reflect the format and size of the defined constants as well as clues such as the alternate character set implementation. A 32-bit library can be used on a 64-bit system, but not necessarily the reverse.Year System Arch Color Char Notes ──────────────────────────────────────────────────────────────── 1992 Solaris 5.2 32 6 17 SVr4 curses 1992 HPUX 9 32 no 8 SVr2 curses 1992 AIX 3.2 32 no 23 SVr2 curses 1994 OSF/1 r3 32 no 23 SVr2 curses 1995 HP-UX 10.00 32 6 16 SVr3 “curses_colr” 1995 HP-UX 10.00 32 6 8 SVr4, X/Open curses 1995 Solaris 5.4 32/64 7 16 X/Open curses 1996 AIX 4.2 32 7 16 X/Open curses 1996 OSF/1 r4 32 6 16 X/Open curses 1997 HP-UX 11.00 32 6 8 X/Open curses 2000 U/Win 32/64 7/31 16 useschtype Notes: Regarding HP-UX, • HP-UX 10.20 (1996) added support for 64-bit PA-RISC proces‐ sors in 1996. • HP-UX 10.30 (1997) marked “curses_colr” obsolete. That version of curses was dropped with HP-UX 11.30 in 2006. Regarding OSF/1 (and Tru64), • These used 64-bit hardware. Like ncurses, the OSF/1 curses interface is not customized for 32-bit and 64-bit versions. • Unlike other systems which evolved from AT&T code, OSF/1 provided a new implementation for X/Open curses. Regarding Solaris, • The initial release of Solaris was in 1992. • Thexpg4 (X/Open) curses was developed by MKS from 1990 to 1995. Sun's copyright began in 1996. • Sun updated the X/Open curses interface after 64-bit sup‐ port was introduced in 1997, but did not modify the SVr4 curses interface. Regarding U/Win, • Development of the curses library began in 1991, stopped in 2000. • Color support was added in 1998. • The library uses onlychtype(nocchar_t). Once X/Open curses was adopted in the mid-1990s, the constraint of a 32-bit interface with many colors and wide-characters forchtype became a moot point. Thecchar_tstructure (whose size and mem‐ bers are not specified in X/Open Curses) could be extended as needed. Other interfaces are rarely used now: • BSD curses was improved slightly in 1993/1994 using Keith Bostic's modification to make the library 8-bit clean fornvi(1). He movedstandout attribute to a structure member. The resulting 4.4BSD curses was replaced by ncurses over the next ten years. • U/Win is rarely used now.
This implementation provides theA_ITALICattribute for terminals which have theenter_italics_mode(sitm) andexit_italics_mode (ritm) capabilities. Italics are not mentioned in X/Open Curses. Unlike the other video attributes,A_ITALICis unrelated to theset_attributescapabilities. This implementation makes the as‐ sumption thatexit_attribute_modemay also reset italics. Each of the functions added by XSI Curses has a parameteropts, which X/Open Curses still (after more than twenty years) documents as reserved for future use, saying that it should beNULL. This implementation uses that parameter in ABI 6 for the functions which have a color-pair parameter to supportextended color pairs: • For functions which modify the color, e.g.,wattr_setandwat‐tr_on, ifopts is set it is treated as a pointer toint, and used to set the color pair instead of theshortpair parame‐ ter. • For functions which retrieve the color, e.g.,wattr_get, ifopts is set it is treated as a pointer toint, and used to re‐ trieve the color pair as anintvalue, in addition to retriev‐ ing it via the standard pointer toshortparameter. • For functions which turn attributes off, e.g.,wattr_off, theopts parameter is ignored except except to check that it isNULL.
These functions are supported in the XSI Curses standard, Issue 4. The standard defined the dedicated type for highlights,attr_t, which was not defined in SVr4 curses. The functions takingattr_t arguments were not supported under SVr4. Very old versions of this library did not force an update of the screen when changing the attributes. Usetouchwinto force the screen to match the updated attributes. The XSI Curses standard states that whether the traditional func‐ tionsattron/attroff/attrsetcan manipulate attributes other thanA_BLINK,A_BOLD,A_DIM,A_REVERSE,A_STANDOUT, orA_UNDERLINEis “unspecified”. Under this implementation as well as SVr4 curses, these functions correctly manipulate all other highlights (specif‐ ically,A_ALTCHARSET,A_PROTECT, andA_INVIS). XSI Curses added these entry points:attr_get,attr_on,attr_off,attr_set,wattr_on,wattr_off,wattr_get,wattr_set The new functions are intended to work with a new series of high‐ light macros prefixed withWA_. The older macros have direct counterparts in the newer set of names:Name Description ────────────────────────────────────────────────────────────WA_NORMALNormal display (no highlight)WA_STANDOUTBest highlighting mode of the terminal.WA_UNDERLINEUnderliningWA_REVERSEReverse videoWA_BLINKBlinkingWA_DIMHalf brightWA_BOLDExtra bright or boldWA_ALTCHARSETAlternate character set XSI curses does not assign values to these symbols, nor does it state whether or not they are related to the similarly-named A_NORMAL, etc.: • The XSI curses standard specifies that each pair of corre‐ spondingA_andWA_-using functions operates on the same cur‐ rent-highlight information. • However, in some implementations, those symbols have unrelated values. For example, the Solarisxpg4 (X/Open) curses declaresattr_t to be an unsigned short integer (16-bits), whilechtypeis a unsigned integer (32-bits). TheWA_symbols in this case are different from theA_symbols because they are used for a smaller datatype which does not representA_CHARTEXTorA_COL‐OR. In this implementation (as in many others), the values happen to be the same because it simplifies copying information be‐ tweenchtypeandcchar_tvariables. • Because ncurses'sattr_tcan hold a color pair (in theA_COLOR field), a call towattr_on,wattr_off, orwattr_setmay alter the window's color. If the color pair information in the at‐ tribute parameter is zero, no change is made to the window's color. This is consistent with SVr4 curses; X/Open Curses does not specify this. The XSI standard extended conformance level adds new highlightsA_HORIZONTAL,A_LEFT,A_LOW,A_RIGHT,A_TOP,A_VERTICAL(and cor‐ respondingWA_macros for each). As of August 2013, no known ter‐ minal provides these highlights (i.e., via thesgr1capability).
All routines return the integerOKon success, orERRon failure. X/Open does not define any error conditions. This implementation • returns an error if the window pointer is null. • returns an error if the color pair parameter forwcolor_setis outside the range 0..COLOR_PAIRS-1. • does not return an error if either of the parameters ofwat‐tr_getused for retrieving attribute or color-pair values isNULL. Functions with a “mv” prefix first perform a cursor movement usingwmove, and return an error if the position is outside the window, or if the window pointer is null.
curses(3X),curs_addch(3X),curs_addstr(3X),curs_bkgd(3X),curs_printw(3X),curs_variables(3X)
This page is part of thencurses (new curses) project. Informa‐ tion about the project can be found at ⟨https://www.gnu.org/software/ncurses/ncurses.html⟩. If you have a bug report for this manual page, send it to bug-ncurses-request@gnu.org. This page was obtained from the project's upstream Git mirror of the CVS repository ⟨https://github.com/mirror/ncurses.git⟩ on 2025-08-11. (At that time, the date of the most recent commit that was found in the repository was 2023-03-12.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which isnot part of the original manual page), send a mail to man-pages@man7.orgcurs_attr(3X)HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |