FAQ (8275B)
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 ## Some _random program_ complains that st is unknown/not recognised/unsupported/whatever! 6 7 It means that st doesn’t have any terminfo entry on your system. Chances are 8 you did not `make install`. If you just want to test it without installing it, 9 you can manually run `tic -sx st.info`. 10 11 ## Nothing works, and nothing is said about an unknown terminal! 12 13 * Some programs just assume they’re running in xterm i.e. they don’t rely on 14 terminfo. What you see is the current state of the “xterm compliance”. 15 * Some programs don’t complain about the lacking st description and default to 16 another terminal. In that case see the question about terminfo. 17 18 ## How do I scroll back up? 19 20 Using a terminal multiplexer. 21 22 * `st -e tmux` using C-b [ 23 * `st -e screen` using C-a ESC 24 25 ## Why doesn't the Del key work in some programs? 26 27 Taken from the terminfo manpage: 28 29 If the terminal has a keypad that transmits codes when the keys 30 are pressed, this information can be given. Note that it is not 31 possible to handle terminals where the keypad only works in 32 local (this applies, for example, to the unshifted HP 2621 keys). 33 If the keypad can be set to transmit or not transmit, give these 34 codes as smkx and rmkx. Otherwise the keypad is assumed to 35 always transmit. 36 37 In the st case smkx=E[?1hE= and rmkx=E[?1lE>, so it is mandatory that 38 applications which want to test against keypad keys send these 39 sequences. 40 41 But buggy applications (like bash and irssi, for example) don't do this. A fast 42 solution for them is to use the following command: 43 44 $ printf '\033[?1h\033=' >/dev/tty 45 46 or 47 $ tput smkx 48 49 In the case of bash, readline is used. Readline has a different note in its 50 manpage about this issue: 51 52 enable-keypad (Off) 53 When set to On, readline will try to enable the 54 application keypad when it is called. Some systems 55 need this to enable arrow keys. 56 57 Adding this option to your .inputrc will fix the keypad problem for all 58 applications using readline. 59 60 If you are using zsh, then read the zsh FAQ 61 <http://zsh.sourceforge.net/FAQ/zshfaq03.html#l25>: 62 63 It should be noted that the O / [ confusion can occur with other keys 64 such as Home and End. Some systems let you query the key sequences 65 sent by these keys from the system's terminal database, terminfo. 66 Unfortunately, the key sequences given there typically apply to the 67 mode that is not the one zsh uses by default (it's the "application" 68 mode rather than the "raw" mode). Explaining the use of terminfo is 69 outside of the scope of this FAQ, but if you wish to use the key 70 sequences given there you can tell the line editor to turn on 71 "application" mode when it starts and turn it off when it stops: 72 73 function zle-line-init () { echoti smkx } 74 function zle-line-finish () { echoti rmkx } 75 zle -N zle-line-init 76 zle -N zle-line-finish 77 78 Putting these lines into your .zshrc will fix the problems. 79 80 ## How can I use meta in 8bit mode? 81 82 St supports meta in 8bit mode, but the default terminfo entry doesn't 83 use this capability. If you want it, you have to use the 'st-meta' value 84 in TERM. 85 86 ## I cannot compile st in OpenBSD 87 88 OpenBSD lacks librt, despite it being mandatory in POSIX 89 <http://pubs.opengroup.org/onlinepubs/9699919799/utilities/c99.html#tag_20_11_13>. 90 If you want to compile st for OpenBSD you have to remove -lrt from config.mk, and 91 st will compile without any loss of functionality, because all the functions are 92 included in libc on this platform. 93 94 ## The Backspace Case 95 96 St is emulating the Linux way of handling backspace being delete and delete being 97 backspace. 98 99 This is an issue that was discussed in suckless mailing list 100 <https://lists.suckless.org/dev/1404/20697.html>. Here is why some old grumpy 101 terminal users wants its backspace to be how he feels it: 102 103 Well, I am going to comment why I want to change the behaviour 104 of this key. When ASCII was defined in 1968, communication 105 with computers was done using punched cards, or hardcopy 106 terminals (basically a typewriter machine connected with the 107 computer using a serial port). ASCII defines DELETE as 7F, 108 because, in punched-card terms, it means all the holes of the 109 card punched; it is thus a kind of 'physical delete'. In the 110 same way, the BACKSPACE key was a non-destructive backspace, 111 as on a typewriter. So, if you wanted to delete a character, 112 you had to BACKSPACE and then DELETE. Another use of BACKSPACE 113 was to type accented characters, for example 'a BACKSPACE `'. 114 The VT100 had no BACKSPACE key; it was generated using the 115 CONTROL key as another control character (CONTROL key sets to 116 0 b7 b6 b5, so it converts H (code 0x48) into BACKSPACE (code 117 0x08)), but it had a DELETE key in a similar position where 118 the BACKSPACE key is located today on common PC keyboards. 119 All the terminal emulators emulated the difference between 120 these keys correctly: the backspace key generated a BACKSPACE 121 (^H) and delete key generated a DELETE (^?). 122 123 But a problem arose when Linus Torvalds wrote Linux. Unlike 124 earlier terminals, the Linux virtual terminal (the terminal 125 emulator integrated in the kernel) returned a DELETE when 126 backspace was pressed, due to the VT100 having a DELETE key in 127 the same position. This created a lot of problems (see [1] 128 and [2]). Since Linux has become the king, a lot of terminal 129 emulators today generate a DELETE when the backspace key is 130 pressed in order to avoid problems with Linux. The result is 131 that the only way of generating a BACKSPACE on these systems 132 is by using CONTROL + H. (I also think that emacs had an 133 important point here because the CONTROL + H prefix is used 134 in emacs in some commands (help commands).) 135 136 From point of view of the kernel, you can change the key 137 for deleting a previous character with stty erase. When you 138 connect a real terminal into a machine you describe the type 139 of terminal, so getty configures the correct value of stty 140 erase for this terminal. In the case of terminal emulators, 141 however, you don't have any getty that can set the correct 142 value of stty erase, so you always get the default value. 143 For this reason, it is necessary to add 'stty erase ^H' to your 144 profile if you have changed the value of the backspace key. 145 Of course, another solution is for st itself to modify the 146 value of stty erase. I usually have the inverse problem: 147 when I connect to non-Unix machines, I have to press CONTROL + 148 h to get a BACKSPACE. The inverse problem occurs when a user 149 connects to my Unix machines from a different system with a 150 correct backspace key. 151 152 [1] http://www.ibb.net/~anne/keyboard.html 153 [2] http://www.tldp.org/HOWTO/Keyboard-and-Console-HOWTO-5.html 154 155 ## But I really want the old grumpy behaviour of my terminal 156 157 Apply [1]. 158 159 [1] https://st.suckless.org/patches/delkey 160 161 ## Why do images not work in st (in programs such as w3m)? 162 163 This is a terrible hack that overdraws an image on top of the terminal emulator 164 window. It also relies on a very specific way the terminal draws it's contents. 165 166 A more proper (but limited way) would be using sixels. Which st doesn't 167 support. 168 169 ## BadLength X error in Xft when trying to render emoji 170 171 Xft makes st crash when rendering color emojis with the following error: 172 173 "X Error of failed request: BadLength (poly request too large or internal Xlib length error)" 174 Major opcode of failed request: 139 (RENDER) 175 Minor opcode of failed request: 20 (RenderAddGlyphs) 176 Serial number of failed request: 1595 177 Current serial number in output stream: 1818" 178 179 This is a known bug in Xft (not st) which happens on some platforms and 180 combination of particular fonts and fontconfig settings. 181 182 See also: 183 https://gitlab.freedesktop.org/xorg/lib/libxft/issues/6 184 https://bugs.freedesktop.org/show_bug.cgi?id=107534 185 https://bugzilla.redhat.com/show_bug.cgi?id=1498269 186 187 The solution is to remove color emoji fonts or disable this in the fontconfig 188 XML configuration. As an ugly workaround (which may work only on newer 189 fontconfig versions (FC_COLOR)), the following code can be used to mask color 190 fonts: 191 192 FcPatternAddBool(fcpattern, FC_COLOR, FcFalse); 193 194 Please don't bother reporting this bug to st, but notify the upstream Xft 195 developers about fixing this bug.