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	FAQ - st - simple terminal
	git clone git://git.suckless.org/st
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	FAQ (9923B)
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	1 ## Why does st not handle utmp entries?
	2
	3 Use the excellent tool of [utmp](https://git.suckless.org/utmp/) for thi…
	4
	5
	6 ## Some _random program_ complains that st is unknown/not recognised/uns…
	7
	8 It means that st doesn’t have any terminfo entry on your system. Chanc…
	9 you did not `make install`. If you just want to test it without installi…
	10 you can manually run `tic -sx st.info`.
	11
	12
	13 ## Nothing works, and nothing is said about an unknown terminal!
	14
	15 * Some programs just assume they’re running in xterm i.e. they don’t…
	16 terminfo. What you see is the current state of the “xterm compliance…
	17 * Some programs don’t complain about the lacking st description and de…
	18 another terminal. In that case see the question about terminfo.
	19
	20
	21 ## How do I scroll back up?
	22
	23 * Using a terminal multiplexer.
	24 * `st -e tmux` using C-b [
	25 * `st -e screen` using C-a ESC
	26 * Using the excellent tool of [scroll](https://git.suckless.org/scroll/).
	27 * Using the scrollback [patch](https://st.suckless.org/patches/scrollbac…
	28
	29
	30 ## I would like to have utmp and/or scroll functionality by default
	31
	32 You can add the absolute path of both programs in your config.h file. Yo…
	33 have to modify the value of utmp and scroll variables.
	34
	35
	36 ## Why doesn't the Del key work in some programs?
	37
	38 Taken from the terminfo manpage:
	39
	40 If the terminal has a keypad that transmits codes when the keys
	41 are pressed, this information can be given. Note that it is not
	42 possible to handle terminals where the keypad only works in
	43 local (this applies, for example, to the unshifted HP 2621 keys).
	44 If the keypad can be set to transmit or not transmit, give these
	45 codes as smkx and rmkx. Otherwise the keypad is assumed to
	46 always transmit.
	47
	48 In the st case smkx=E[?1hE= and rmkx=E[?1lE>, so it is mandatory that
	49 applications which want to test against keypad keys send these
	50 sequences.
	51
	52 But buggy applications (like bash and irssi, for example) don't do this.…
	53 solution for them is to use the following command:
	54
	55 $ printf '\033[?1h\033=' >/dev/tty
	56
	57 or
	58 $ tput smkx
	59
	60 In the case of bash, readline is used. Readline has a different note in …
	61 manpage about this issue:
	62
	63 enable-keypad (Off)
	64 When set to On, readline will try to enable the
	65 application keypad when it is called. Some systems
	66 need this to enable arrow keys.
	67
	68 Adding this option to your .inputrc will fix the keypad problem for all
	69 applications using readline.
	70
	71 If you are using zsh, then read the zsh FAQ
	72 <http://zsh.sourceforge.net/FAQ/zshfaq03.html#l25>:
	73
	74 It should be noted that the O / [ confusion can occur with other…
	75 such as Home and End. Some systems let you query the key sequenc…
	76 sent by these keys from the system's terminal database, terminfo.
	77 Unfortunately, the key sequences given there typically apply to …
	78 mode that is not the one zsh uses by default (it's the "applicat…
	79 mode rather than the "raw" mode). Explaining the use of terminfo…
	80 outside of the scope of this FAQ, but if you wish to use the key
	81 sequences given there you can tell the line editor to turn on
	82 "application" mode when it starts and turn it off when it stops:
	83
	84 function zle-line-init () { echoti smkx }
	85 function zle-line-finish () { echoti rmkx }
	86 zle -N zle-line-init
	87 zle -N zle-line-finish
	88
	89 Putting these lines into your .zshrc will fix the problems.
	90
	91
	92 ## How can I use meta in 8bit mode?
	93
	94 St supports meta in 8bit mode, but the default terminfo entry doesn't
	95 use this capability. If you want it, you have to use the 'st-meta' value
	96 in TERM.
	97
	98
	99 ## I cannot compile st in OpenBSD
	100
	101 OpenBSD lacks librt, despite it being mandatory in POSIX
	102 <http://pubs.opengroup.org/onlinepubs/9699919799/utilities/c99.html#tag_…
	103 If you want to compile st for OpenBSD you have to remove -lrt from confi…
	104 st will compile without any loss of functionality, because all the funct…
	105 included in libc on this platform.
	106
	107
	108 ## The Backspace Case
	109
	110 St is emulating the Linux way of handling backspace being delete and del…
	111 backspace.
	112
	113 This is an issue that was discussed in suckless mailing list
	114 <https://lists.suckless.org/dev/1404/20697.html>. Here is why some old g…
	115 terminal users wants its backspace to be how he feels it:
	116
	117 Well, I am going to comment why I want to change the behaviour
	118 of this key. When ASCII was defined in 1968, communication
	119 with computers was done using punched cards, or hardcopy
	120 terminals (basically a typewriter machine connected with the
	121 computer using a serial port). ASCII defines DELETE as 7F,
	122 because, in punched-card terms, it means all the holes of the
	123 card punched; it is thus a kind of 'physical delete'. In the
	124 same way, the BACKSPACE key was a non-destructive backspace,
	125 as on a typewriter. So, if you wanted to delete a character,
	126 you had to BACKSPACE and then DELETE. Another use of BACKSPACE
	127 was to type accented characters, for example 'a BACKSPACE `'.
	128 The VT100 had no BACKSPACE key; it was generated using the
	129 CONTROL key as another control character (CONTROL key sets to
	130 0 b7 b6 b5, so it converts H (code 0x48) into BACKSPACE (code
	131 0x08)), but it had a DELETE key in a similar position where
	132 the BACKSPACE key is located today on common PC keyboards.
	133 All the terminal emulators emulated the difference between
	134 these keys correctly: the backspace key generated a BACKSPACE
	135 (^H) and delete key generated a DELETE (^?).
	136
	137 But a problem arose when Linus Torvalds wrote Linux. Unlike
	138 earlier terminals, the Linux virtual terminal (the terminal
	139 emulator integrated in the kernel) returned a DELETE when
	140 backspace was pressed, due to the VT100 having a DELETE key in
	141 the same position. This created a lot of problems (see [1]
	142 and [2]). Since Linux has become the king, a lot of terminal
	143 emulators today generate a DELETE when the backspace key is
	144 pressed in order to avoid problems with Linux. The result is
	145 that the only way of generating a BACKSPACE on these systems
	146 is by using CONTROL + H. (I also think that emacs had an
	147 important point here because the CONTROL + H prefix is used
	148 in emacs in some commands (help commands).)
	149
	150 From point of view of the kernel, you can change the key
	151 for deleting a previous character with stty erase. When you
	152 connect a real terminal into a machine you describe the type
	153 of terminal, so getty configures the correct value of stty
	154 erase for this terminal. In the case of terminal emulators,
	155 however, you don't have any getty that can set the correct
	156 value of stty erase, so you always get the default value.
	157 For this reason, it is necessary to add 'stty erase ^H' to your
	158 profile if you have changed the value of the backspace key.
	159 Of course, another solution is for st itself to modify the
	160 value of stty erase. I usually have the inverse problem:
	161 when I connect to non-Unix machines, I have to press CONTROL +
	162 h to get a BACKSPACE. The inverse problem occurs when a user
	163 connects to my Unix machines from a different system with a
	164 correct backspace key.
	165
	166 [1] http://www.ibb.net/~anne/keyboard.html
	167 [2] http://www.tldp.org/HOWTO/Keyboard-and-Console-HOWTO-5.html
	168
	169
	170 ## But I really want the old grumpy behaviour of my terminal
	171
	172 Apply [1].
	173
	174 [1] https://st.suckless.org/patches/delkey
	175
	176
	177 ## Why do images not work in st using the w3m image hack?
	178
	179 w3mimg uses a hack that draws an image on top of the terminal emulator D…
	180 window. The hack relies on the terminal to use a single buffer to draw i…
	181 contents directly.
	182
	183 st uses double-buffered drawing so the image is quickly replaced and may…
	184 short flicker effect.
	185
	186 Below is a patch example to change st double-buffering to a single Drawa…
	187 buffer.
	188
	189 diff --git a/x.c b/x.c
	190 --- a/x.c
	191 +++ b/x.c
	192 @@ -732,10 +732,6 @@ xresize(int col, int row)
	193 win.tw = col * win.cw;
	194 win.th = row * win.ch;
	195
	196 - XFreePixmap(xw.dpy, xw.buf);
	197 - xw.buf = XCreatePixmap(xw.dpy, xw.win, win.w, win.h,
	198 - DefaultDepth(xw.dpy, xw.scr));
	199 - XftDrawChange(xw.draw, xw.buf);
	200 xclear(0, 0, win.w, win.h);
	201
	202 /* resize to new width */
	203 @@ -1148,8 +1144,7 @@ xinit(int cols, int rows)
	204 gcvalues.graphics_exposures = False;
	205 dc.gc = XCreateGC(xw.dpy, parent, GCGraphicsExposures,
	206 &gcvalues);
	207 - xw.buf = XCreatePixmap(xw.dpy, xw.win, win.w, win.h,
	208 - DefaultDepth(xw.dpy, xw.scr));
	209 + xw.buf = xw.win;
	210 XSetForeground(xw.dpy, dc.gc, dc.col[defaultbg].pixel);
	211 XFillRectangle(xw.dpy, xw.buf, dc.gc, 0, 0, win.w, win.h);
	212
	213 @@ -1632,8 +1627,6 @@ xdrawline(Line line, int x1, int y1, int x2)
	214 void
	215 xfinishdraw(void)
	216 {
	217 - XCopyArea(xw.dpy, xw.buf, xw.win, dc.gc, 0, 0, win.w,
	218 - win.h, 0, 0);
	219 XSetForeground(xw.dpy, dc.gc,
	220 dc.col[IS_SET(MODE_REVERSE)?
	221 defaultfg : defaultbg].pixel);
	222
	223
	224 ## BadLength X error in Xft when trying to render emoji
	225
	226 Xft makes st crash when rendering color emojis with the following error:
	227
	228 "X Error of failed request: BadLength (poly request too large or intern…
	229 Major opcode of failed request: 139 (RENDER)
	230 Minor opcode of failed request: 20 (RenderAddGlyphs)
	231 Serial number of failed request: 1595
	232 Current serial number in output stream: 1818"
	233
	234 This is a known bug in Xft (not st) which happens on some platforms and
	235 combination of particular fonts and fontconfig settings.
	236
	237 See also:
	238 https://gitlab.freedesktop.org/xorg/lib/libxft/issues/6
	239 https://bugs.freedesktop.org/show_bug.cgi?id=107534
	240 https://bugzilla.redhat.com/show_bug.cgi?id=1498269
	241
	242 The solution is to remove color emoji fonts or disable this in the fontc…
	243 XML configuration. As an ugly workaround (which may work only on newer
	244 fontconfig versions (FC_COLOR)), the following code can be used to mask …
	245 fonts:
	246
	247 FcPatternAddBool(fcpattern, FC_COLOR, FcFalse);
	248
	249 Please don't bother reporting this bug to st, but notify the upstream Xft
	250 developers about fixing this bug.
	251
	252 As of 2022-09-05 this now seems to be finally fixed in libXft 2.3.5:
	253 https://gitlab.freedesktop.org/xorg/lib/libxft/-/blob/libXft-2.3.5/NEWS