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(git version 2020/01 suckless.org)

Why does st not handle utmp entries?

Use the excellent tool of utmp for this task.

Some random program complains that st is unknown/not recognised/unsupported/whatever!

It means that st doesn’t have any terminfo entry on your system. Chances are you did not make install. If you just want to test it without installing it, you can manually run tic -sx st.info.

Nothing works, and nothing is said about an unknown terminal!

  • Some programs just assume they’re running in xterm i.e. they don’t rely on terminfo. What you see is the current state of the “xterm compliance”.
  • Some programs don’t complain about the lacking st description and default to another terminal. In that case see the question about terminfo.

How do I scroll back up?

Using a terminal multiplexer.

  • st -e tmux using C-b [
  • st -e screen using C-a ESC

Why doesn't the Del key work in some programs?

Taken from the terminfo manpage:

If the terminal has a keypad that transmits codes when the keys
are pressed, this information can be given. Note that it is not
possible to handle terminals where the keypad only works in
local (this applies, for example, to the unshifted HP 2621 keys).
If the keypad can be set to transmit or not transmit, give these
codes as smkx and rmkx. Otherwise the keypad is assumed to
always transmit.

In the st case smkx=E[?1hE= and rmkx=E[?1lE>, so it is mandatory that applications which want to test against keypad keys send these sequences.

But buggy applications (like bash and irssi, for example) don't do this. A fast solution for them is to use the following command:

$ printf '\033[?1h\033=' >/dev/tty

or $ tput smkx

In the case of bash, readline is used. Readline has a different note in its manpage about this issue:

enable-keypad (Off)
	When set to On, readline will try to enable the
	application keypad when it is called. Some systems
	need this to enable arrow keys.

Adding this option to your .inputrc will fix the keypad problem for all applications using readline.

If you are using zsh, then read the zsh FAQ http://zsh.sourceforge.net/FAQ/zshfaq03.html#l25:

It should be noted that the O / [ confusion can occur with other keys
such as Home and End. Some systems let you query the key sequences
sent by these keys from the system's terminal database, terminfo.
Unfortunately, the key sequences given there typically apply to the
mode that is not the one zsh uses by default (it's the "application"
mode rather than the "raw" mode). Explaining the use of terminfo is
outside of the scope of this FAQ, but if you wish to use the key
sequences given there you can tell the line editor to turn on
"application" mode when it starts and turn it off when it stops:

	function zle-line-init () { echoti smkx }
	function zle-line-finish () { echoti rmkx }
	zle -N zle-line-init
	zle -N zle-line-finish

Putting these lines into your .zshrc will fix the problems.

How can I use meta in 8bit mode?

St supports meta in 8bit mode, but the default terminfo entry doesn't use this capability. If you want it, you have to use the 'st-meta' value in TERM.

I cannot compile st in OpenBSD

OpenBSD lacks librt, despite it being mandatory in POSIX http://pubs.opengroup.org/onlinepubs/9699919799/utilities/c99.html#tag_20_11_13. If you want to compile st for OpenBSD you have to remove -lrt from config.mk, and st will compile without any loss of functionality, because all the functions are included in libc on this platform.

The Backspace Case

St is emulating the Linux way of handling backspace being delete and delete being backspace.

This is an issue that was discussed in suckless mailing list https://lists.suckless.org/dev/1404/20697.html. Here is why some old grumpy terminal users wants its backspace to be how he feels it:

Well, I am going to comment why I want to change the behaviour
of this key. When ASCII was defined in 1968, communication
with computers was done using punched cards, or hardcopy
terminals (basically a typewriter machine connected with the
computer using a serial port).  ASCII defines DELETE as 7F,
because, in punched-card terms, it means all the holes of the
card punched; it is thus a kind of 'physical delete'. In the
same way, the BACKSPACE key was a non-destructive backspace,
as on a typewriter.  So, if you wanted to delete a character,
you had to BACKSPACE and then DELETE.  Another use of BACKSPACE
was to type accented characters, for example 'a BACKSPACE `'.
The VT100 had no BACKSPACE key; it was generated using the
CONTROL key as another control character (CONTROL key sets to
0 b7 b6 b5, so it converts H (code 0x48) into BACKSPACE (code
0x08)), but it had a DELETE key in a similar position where
the BACKSPACE key is located today on common PC keyboards.
All the terminal emulators emulated the difference between
these keys correctly: the backspace key generated a BACKSPACE
(^H) and delete key generated a DELETE (^?).

But a problem arose when Linus Torvalds wrote Linux. Unlike
earlier terminals, the Linux virtual terminal (the terminal
emulator integrated in the kernel) returned a DELETE when
backspace was pressed, due to the VT100 having a DELETE key in
the same position.  This created a lot of problems (see [1]
and [2]). Since Linux has become the king, a lot of terminal
emulators today generate a DELETE when the backspace key is
pressed in order to avoid problems with Linux. The result is
that the only way of generating a BACKSPACE on these systems
is by using CONTROL + H. (I also think that emacs had an
important point here because the CONTROL + H prefix is used
in emacs in some commands (help commands).)

From point of view of the kernel, you can change the key
for deleting a previous character with stty erase. When you
connect a real terminal into a machine you describe the type
of terminal, so getty configures the correct value of stty
erase for this terminal. In the case of terminal emulators,
however, you don't have any getty that can set the correct
value of stty erase, so you always get the default value.
For this reason, it is necessary to add 'stty erase ^H' to your
profile if you have changed the value of the backspace key.
Of course, another solution is for st itself to modify the
value of stty erase.  I usually have the inverse problem:
when I connect to non-Unix machines, I have to press CONTROL +
h to get a BACKSPACE. The inverse problem occurs when a user
connects to my Unix machines from a different system with a
correct backspace key.

[1] http://www.ibb.net/~anne/keyboard.html
[2] http://www.tldp.org/HOWTO/Keyboard-and-Console-HOWTO-5.html

But I really want the old grumpy behaviour of my terminal

Apply [1].

[1] https://st.suckless.org/patches/delkey

Why do images not work in st (in programs such as w3m)?

This is a terrible hack that overdraws an image on top of the terminal emulator window. It also relies on a very specific way the terminal draws it's contents.

A more proper (but limited way) would be using sixels. Which st doesn't support.

BadLength X error in Xft when trying to render emoji

Xft makes st crash when rendering color emojis with the following error:

"X Error of failed request: BadLength (poly request too large or internal Xlib length error)" Major opcode of failed request: 139 (RENDER) Minor opcode of failed request: 20 (RenderAddGlyphs) Serial number of failed request: 1595 Current serial number in output stream: 1818"

This is a known bug in Xft (not st) which happens on some platforms and combination of particular fonts and fontconfig settings.

See also: https://gitlab.freedesktop.org/xorg/lib/libxft/issues/6 https://bugs.freedesktop.org/show_bug.cgi?id=107534 https://bugzilla.redhat.com/show_bug.cgi?id=1498269

The solution is to remove color emoji fonts or disable this in the fontconfig XML configuration. As an ugly workaround (which may work only on newer fontconfig versions (FC_COLOR)), the following code can be used to mask color fonts:

FcPatternAddBool(fcpattern, FC_COLOR, FcFalse);

Please don't bother reporting this bug to st, but notify the upstream Xft developers about fixing this bug.