foot

The fast, lightweight and minimalistic Wayland terminal emulator.

Index

1. Features
2. Troubleshooting
3. Why the name 'foot'?
4. Fonts
5. Shortcuts
   1. Keyboard
      1. Normal mode
      2. Scrollback search
   2. Mouse
6. Server (daemon) mode
7. Alt/meta
8. Backspace
9. DPI and font size
10. Supported OSCs
11. Programmatically checking if running in foot
12. Requirements
    1. Running
    2. Building
13. Installing
    1. Arch Linux
    2. Other
       1. Setup
       2. Release build
          1. Profile Guided Optimization
       3. Debug build
       4. Running the new build
14. Credits
15. Bugs
16. Mastodon

Features

• Fast (see benchmarks)

• Lightweight, in dependencies, on-disk and in-memory

• Wayland native

• DE agnostic

• User configurable font fallback

• On-the-fly font resize

• On-the-fly DPI font size adjustment

• Scrollback search

• Color emoji support

• Server/daemon mode (one master process, many windows)

• Multi-seat

• Synchronized Updates support

• Sixel image support

  

Troubleshooting

See the wiki

Why the name 'foot'?

I'm bad at names. Most of my projects usually start out as foo something (for example, yambar was f00bar for a while).

So why foot?

foo terminal → footerm → foot

Pretty bad, I know.

As a side note, if you pronounce the foo part of foot the same way you pronounce foobar, then foot sounds a lot like the Swedish word fot, which incidentally means (you guessed it) foot.

Fonts

foot supports all fonts that can be loaded by freetype, including bitmap fonts and color emoji fonts.

Foot uses fontconfig to locate and configure the font(s) to use. Since fontconfig's fallback mechanism is imperfect, especially for monospace fonts (it doesn't prefer monospace fonts even though the requested font is one), foot allows you, the user, to configure the fallback fonts to use.

This also means you can configure each fallback font individually; you want that fallback font to use this size, and you want that other fallback font to be italic? No problem!

If a glyph cannot be found in any of the user configured fallback fonts, then fontconfig's list is used.

Shortcuts

These are the default shortcuts. See man 5 foot and the example footrc to see how these can be changed.

Keyboard

Normal mode

shift+page up/page down

Scroll up/down in history

ctrl+shift+c

Copy selected text to the clipboard

ctrl+shift+v

Paste from clipboard

ctrl+shift+r

Start a scrollback search

ctrl++, ctrl+=

Increase font size by 0,5pt

ctrl+-

Decrease font size by 0,5pt

ctrl+0

Reset font size

ctrl+shift+n

Spawn a new terminal. If the shell has been configured to emit the OSC 7 escape sequence, the new terminal will start in the current working directory.

Scrollback search

ctrl+r

Search backward for next match

ctrl+s

Search forward for next match

ctrl+w

Extend current selection (and thus the search criteria) to the end of the word, or the next word if currently at a word separating character.

ctrl+shift+w

Same as ctrl+w, except that the only word separating characters are whitespace characters.

escape, ctrl+g

Cancel the search

return

Finish the search and copy the current match to the primary selection

Mouse

left - single-click

Drag to select; when released, the selected text is copied to the primary selection. This feature is disabled when client has enabled mouse tracking.

Holding shift enables selection in mouse tracking enabled clients.

Holding ctrl will create a block selection.

left - double-click

Selects the word (separated by spaces, period, comma, parenthesis etc) under the pointer. Hold ctrl to select everything under the pointer up to, and until, the next space characters.

left - triple-click

Selects the entire row

middle

Paste from primary selection

right

Extend current selection

wheel

Scroll up/down in history

Server (daemon) mode

When run normally, foot is a single-window application; if you want another window, start another foot process.

However, foot can also be run in a server mode. In this mode, one process hosts multiple windows. Note that this is nothing like tabs. When first started in server mode, no windows are available.

You open new windows by running footclient. This is a small process that instructs the foot server to open a new terminal window. The client process remains running until the terminal window is closed. The exit value of the client process is that of the shell that was running in the terminal window.

The point of this mode is a) reduced memory footprint - all terminal windows will share fonts and glyph cache, and b) reduced startup time - loading fonts and populating the glyph cache takes time, but in server mode it only happens once.

The downside is a performance penalty; all windows' input and output are multiplexed in the same thread (but each window will have its own set of rendering threads). This means that if one window is very busy with, for example, producing output, then other windows will suffer.

And of course, should the server process crash, all windows will be gone.

Typical usage would be to start the server process (foot --server) when starting your Wayland compositor (i.e. logging in to your desktop), and then run footclient instead of foot whenever you want to launch a new terminal.

Alt/meta

By default, foot prefixes Meta characters with ESC. This corresponds to XTerm's metaSendsEscape option set to true.

This can be disabled programatically with \E[?1036l (and enabled again with \E[?1036h).

When disabled, foot will instead set the 8:th bit of meta character and then UTF-8 encode it. This corresponds to XTerm's eightBitMeta option set to true.

This can also be disabled programatically with rmm (reset meta mode, \E[?1034l), and enabled again with smm (set meta mode, \E[?1034h).

Backspace

Foot transmits DEL (^?) on backspace. This corresponds to XTerm's backarrowKey option set to false, and to DECBKM being reset.

To instead transmit BS (^H), press ctrl+backspace.

Note that foot does not implement DECBKM, and that the behavior described above cannot be changed.

Finally, pressing alt will prefix the transmitted byte with ESC.

DPI and font size

Font sizes are apparently a complex thing. Many applications use a fixed DPI of 96. They may also multiply it with the monitor's scale factor.

This results in fonts with different physical sizes (i.e. if measured by a ruler) when rendered on screens with different DPI values. Even if the configured font size is the same.

This is not how it is meant to be. Fonts are measured in point sizes for a reason; a given point size should have the same height on all mediums, be it printers or monitors, regardless of their DPI.

Foot will always use the monitor's physical DPI value. Scale factors are irrelevant (well, they affect e.g. padding, but not the font size). This means the glyphs rendered by foot should always have the same physical height, regardless of monitor.

Foot will re-size the fonts on-the-fly when the window is moved between screens with different DPIs values. If the window covers multiple screens, with different DPIs, the highest DPI will be used.

Tip: QT applications can be configured to work this way too, by exporting the environment variable QT_WAYLAND_FORCE_DPI=physical.

Note: if you configure pixelsize, rather than size, then DPI changes will not change the font size. Pixels are always pixels.

Supported OSCs

OSC, Operating System Command, are escape sequences that interacts with the terminal emulator itself. Foot implements the following OSCs:

• OSC 0 - change window icon + title (but only title is actually supported)
• OSC 2 - change window title
• OSC 4 - change color palette
• OSC 7 - report CWD
• OSC 10 - change (default) foreground color
• OSC 11 - change (default) background color
• OSC 12 - change cursor color
• OSC 52 - copy/paste clipboard data
• OSC 104 - reset color palette
• OSC 110 - reset default foreground color
• OSC 111 - reset default background color
• OSC 112 - reset cursor color
• OSC 555 - flash screen (foot specific)

Programmatically checking if running in foot

Foot does not set any environment variables that can be used to identify foot (reading TERM is not reliable since the user may have chosen to use a different terminfo).

You can instead use the escape sequences to read the Secondary and Tertiary Device Attributes (secondary/tertiary DA, for short).

The tertiary DA response is always \EP!|464f4f54\E\\. The \EP!| is the standard tertiary DA response prefix, DCS ! |. The trailing \E\\ is of course the standard string terminator, ST.

In the response above, the interresting part is 464f4f54; this is the string FOOT in hex.

The secondary DA response is \E[>1;XXYYZZ;0c, where XXYYZZ is foot's major, minor and patch version numbers, in decimal, using two digits for each number. For example, foot-1.4.2 would respond with \E[>1;010402;0c.

Note: not all terminal emulators implement tertiary DA. Most implement secondary DA, but not all. All should however implement Primary DA.

Thus, a safe way to query the terminal is to request the tertiary, secondary and primary DA all at once, in that order. All terminals should ignore escape sequences they do not recognize. You will have to parse the response (which in foot will consist of all three DA responses, all at once) to determine which requests the terminal emulator actually responded to.

Requirements

Running

• fontconfig
• freetype
• pixman
• wayland (client and cursor libraries)
• xkbcommon
• tllist ¹
• fcft ¹

Building

In addition to the dev variant of the packages above, you need:

• meson
• ninja
• wayland protocols
• ncurses
• scdoc

A note on compilers; in general, foot runs much faster when compiled with gcc instead of clang. A profile-guided gcc build can be more than twice as fast as a clang build.

Note GCC 10.1 has a performance regression that severely affects foot when doing PGO builds and building with -O2; it is about 30-40% slower compared to GCC 9.3.

The work around is simple: make sure you build with -O3. This is the default with meson --buildtype=release, but e.g. makepkg can override it (makepkg uses -O2 by default).

Installing

foot makes use of a couple of libraries I have developed: tllist and fcft. As such, they will most likely not have been installed already. You can either install them as system libraries, or you can build them as subprojects in foot.

When building foot, they will first be searched for as system libraries. If found, foot will link dynamically against them.

If not found, they will be searched for as subprojects. In this case you need to create the subprojects directory and clone https://codeberg.org/dnkl/fcft.git and https://codeberg.org/dnkl/tllist.git (see Other below).

Arch Linux

Install from AUR:

• foot + foot-terminfo
• foot-git + foot-terminfo-git

Or use makepkg to build the bundled PKGBUILD (run makepkg in the source root directory).

Unlike the AUR packages, the bundled PKGBUILD requires tllist and fcft to be installed as system libraries. If you do not want this, please edit the PKGBUILD file, or install manually (see Other below).

Note that it will do a profiling-guided build, and that this requires a running wayland session since it needs to run an intermediate build of foot.

Other

Foot uses meson. If you are unfamiliar with it, the official tutorial might be a good starting point.

I also recommend taking a look at the bundled Arch PKGBUILD file, to see how it builds foot. Especially so if you intend to install a release build of foot, in which case you might be interested in the compiler flags used there.

Setup

If you have not installed tllist and fcft as system libraries, clone them into the subprojects directory:

mkdir -p subprojects
pushd subprojects
git clone https://codeberg.org/dnkl/tllist.git
git clone https://codeberg.org/dnkl/fcft.git
popd

To build, first, create a build directory, and switch to it:

mkdir -p bld/release && cd bld/release

Release build

export CFLAGS+="-O3 -march=native -fno-plt"
meson --buildtype=release --prefix=/usr -Db_lto=true

For performance reasons, I strongly recommend doing a PGO (Profile Guided Optimization) build. This requires a running Wayland session since we will be executing an intermediate build of foot.

If you do not want this, just build:

ninja

and then skip to Running the new build.

For packagers: normally, you would configure compiler flags using -Dc_args. This however "overwrites" CFLAGS. makepkg from Arch, for example, uses CFLAGS to specify the default set of flags.

Thus, we do export CFLAGS+="..." to at least not throw away those flags.

When packaging, you may want to use the default CFLAGS only, but note this: foot is a performance critical application that relies on compiler optimizations to perform well.

In particular, with GCC 10.1, it is very important -O3 is used (and not e.g. -O2) when doing a PGO build.

Profile Guided Optimization

First, make sure you have configured a release build directory, but:

If using Clang, make sure to add -Wno-ignored-optimization-argument -Wno-profile-instr-out-of-date to CFLAGS.

If using GCC, make sure to add -Wno-missing-profile to CFLAGS.

Then, tell meson we want to generate profile data, and build:

meson configure -Db_pgo=generate
ninja

Next, we need to execute the intermediate build of foot, and run a payload inside it that will exercise the performance critical code paths. To do this, we will use the script scripts/generate-alt-random-writes.py:

foot_tmp_file=$(mktemp)
./foot --config=/dev/null --term=xterm sh -c "<path-to-generate-alt-ranodm-writes.py> --scroll --scroll-region --colors-regular --colors-bright --colors-rgb ${foot_tmp_file} && cat ${foot_tmp_file}"
rm ${foot_tmp_file}

You should see a foot window open up, with random colored text. The window should close after ~1-2s.

If using Clang, now do (this requires llvm to have been installed):

llvm-profdata merge default_*profraw --output=default.profdata

Next, tell meson to use the profile data we just generated, and rebuild:

meson configure -Db_pgo=use
ninja

Continue reading in Running the new build

Debug build

meson --buildtype=debug ../..
ninja

Running the new build

You can now run it directly from the build directory:

./foot

But note that it will default to TERM=foot, and that this terminfo has not been installed yet. However, most things should work with the xterm-256color terminfo:

./foot --term xterm-256color

But, I recommend you install the foot and foot-direct terminfo files. You can either copy them manually (typically to /usr/share/terminfo/f - but this is dependens on the distro), or just install everything:

ninja install

Credits

• Ordoviz, for designing and contributing foot's logo.

BUGS

Please report bugs to https://codeberg.org/dnkl/foot/issues

The report should contain the following:

• Which Wayland compositor (and version) you are running
• Foot version (foot --version)
• Log output from foot (start foot from another terminal)
• If reporting a crash, please try to provide a bt full backtrace with symbols (i.e. use a debug build)
• Steps to reproduce. The more details the better

Mastodon

Every now and then I post foot related updates on @dnkl@linuxrocks.online

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1. can also be built as subprojects, in which case they are statically linked. ↩︎