FAQ (9923B)
1 ## Why does st not handle utmp entries? 2 3 Use the excellent tool of [utmp](https://git.suckless.org/utmp/) for this task. 4 5 6 ## Some _random program_ complains that st is unknown/not recognised/unsupported/whatever! 7 8 It means that st doesn’t have any terminfo entry on your system. Chances are 9 you did not `make install`. If you just want to test it without installing it, 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 rely on 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 default to 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/scrollback/). 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. You only 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. A fast 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 its 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 keys 75 such as Home and End. Some systems let you query the key sequences 76 sent by these keys from the system's terminal database, terminfo. 77 Unfortunately, the key sequences given there typically apply to the 78 mode that is not the one zsh uses by default (it's the "application" 79 mode rather than the "raw" mode). Explaining the use of terminfo is 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_20_11_13>. 103 If you want to compile st for OpenBSD you have to remove -lrt from config.mk, and 104 st will compile without any loss of functionality, because all the functions are 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 delete being 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 grumpy 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 Drawable 180 window. The hack relies on the terminal to use a single buffer to draw its 181 contents directly. 182 183 st uses double-buffered drawing so the image is quickly replaced and may show a 184 short flicker effect. 185 186 Below is a patch example to change st double-buffering to a single Drawable 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 internal Xlib length error)" 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 fontconfig 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 color 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