• XDG_CONFIG_HOME/foot/foot.ini (defaulting to $HOME/.config/foot/foot.ini if unset)
• XDG_CONFIG_DIRS/foot/foot.ini (defaulting to /usr/local/etc/xdg/foot/foot.ini if unset)

Examples:

Be aware that, depending on your setup, there may be global FontConfig options that overrides options set here. If an option appears to have no effect, ensure there is no global configuration file that sets the same option with assign or assign_replace; use one of the many append or possibly prepend modes.

For each option, the first font is the primary font. The remaining fonts are fallback fonts that will be used whenever a glyph cannot be found in the primary font.

The fallback fonts are searched in the order they appear. If a glyph cannot be found in any of the fallback fonts, the dynamic fallback list from fontconfig (for the primary font) is searched.

font-bold, font-italic and font-bold-italic allow custom fonts to be used for bold/italic/bold+italic fonts. If left unconfigured, the bold/italic variants of the regular font(s) specified in font are used. Note: you may have to tweak the size(s) of the custom bold/italic fonts to match the regular font.

To disable bold and/or italic fonts, set e.g. font-bold to exactly the same value as font.

size is in points (as defined by the FontConfig format). To set a pixel size, use pixelsize instead. Note that pixel sizes are unaffected by DPI aware rendering (see dpi-aware), but are affected by desktop scaling.

Default: monospace:size=8 (font), not set (font-bold, font-italic, font-bold-italic).

Examples:

font-size-adjustment=0.5   # Adjust by 0.5 points
font-size-adjustment=10px  # Adjust by 10 pixels
font-size-adjustment=7.5%  # Adjust by 7.5 percent

Default: 0.5

The import file has its own section scope. I.e. the including configuration is still in the default section after the include, regardless of which section the included file ends in.

Default: not set.

You can specify a height in pixels by using the px suffix: e.g. line-height=12px.

Warning: when changing the font size at runtime (i.e. zooming in our out), foot will change the line height by the same percentage. However, due to rounding, it is possible the line height will be "too small" for some font sizes, causing e.g. underscores to "disappear".

See also: vertical-letter-offset.

Default: not set.

You can specify a letter spacing in pixels by using the px suffix: e.g. letter-spacing=2px.

See also: horizontal-letter-offset.

Default: 0.

To specify an offset in pixels, append px: e.g. horizontal-letter-offset=2px.

Default: 0.

To specify an offset in pixels, append px: underline-offset=2px.

If left unset (the default), the offset specified in the font is used, or estimated by foot if the font lacks underline positioning information.

Default: unset.

To specify a thickness in pixels, append px: underline-thickness=1px.

If left unset (the default), the thickness specified in the font is used.

Default: unset

To specify a thickness in pixels, append px: strikeout-thickness=1px.

If left unset (the default), the thickness specified in the font is used.

Default: unset

Compared to the default (disabled), bright glyphs on a dark background will appear thicker, and dark glyphs on a light background will appear thinner.

FreeType can limit the effect of the latter, with a technique called stem darkening. It is only available for CFF fonts (OpenType, .otf) and disabled by default (in FreeType). You can enable it by setting the environment variable FREETYPE_PROPERTIES="cff:no-stem-darkening=0" before starting foot.

Also be aware that many fonts have been developed on systems that do not do gamma-correct blending, and may therefore look thicker than intended when rendered with gamma-correct blending, since the font designer set the font weight based on incorrect rendering.

In order to represent colors faithfully, higher precision image buffers are required. By default, foot will use 10-bit color channels, if available, when gamma-correct blending is enabled. However, the high precision buffers are slow; if you want to use gamma-correct blending, but prefer speed (throughput and input latency) over accurate colors, you can force 8-bit color channels by setting tweak.surface-bit-depth=8-bit.

Default: no.

When enabled, box/line drawing characters are rendered using font glyphs. This may result in a more uniform look, in some use cases.

When disabled, foot will render the following Unicode codepoints by itself:

Default: no.

When set to yes, fonts are sized using the monitor's DPI, making a font of a given size have the same physical size, regardless of monitor. In other words, if you drag a foot window between different monitors, the font size remains the same.

In this mode, the monitor's scaling factor is ignored; doubling the scaling factor will not double the font size.

When set to no, the monitor's DPI is ignored. The font is instead sized using the monitor's scaling factor; doubling the scaling factor does double the font size.

Note that this option typically does not work with bitmap fonts, which only contains a pre-defined set of sizes, and cannot be dynamically scaled. Whichever size (of the available ones) that best matches the DPI or scaling factor, will be used.

Also note that if the font size has been specified in pixels (:pixelsize=N, instead of :size=N), DPI scaling (dpi-aware=yes) will have no effect (the specified pixel size will be used as is). But, if the monitor's scaling factor is used to size the font (dpi-aware=no), the font's pixel size will be multiplied with the scaling factor.

Default: no

This will add at least X pixels on both the left and right sides, and Y pixels on the top and bottom sides. The grid content will be anchored in the top left corner. I.e. if the window manager forces an odd window size on foot, the additional pixels will be added to the right and bottom sides.

To instead center the grid content, append center (e.g. pad=5x5 center).

Default: 0x0.

In other words, while you are fiddling with the window size, foot does not send the updated dimensions to the client. It also does a fast "truncating" resize of the grid, instead of actually reflowing the contents. Only when you pause the fiddling for resize-delay-ms milliseconds is the client updated, and the contents properly reflowed.

Emphasis is on while here; as soon as the interactive resize ends (i.e. when you let go of the window border), the final dimensions is sent to the client, without any delays.

Setting it to 0 disables the delay completely.

Default: 100.

When set to yes, the window size will be constrained to multiples of the cell size (plus any configured padding). When set to no, the window size will be unconstrained, and padding may be adjusted as necessary to accommodate window sizes that are not multiples of the cell size.

This option only applies to floating windows. Sizes of maxmized, tiled or fullscreen windows will not be constrained to multiples of the cell size.

Default: yes

When set to yes, the window size will be adjusted with changes in font size to preserve the dimensions of the text grid. When set to no, the window size will remain constant and the text grid will be adjusted as necessary to fit the window.

This option only applies to floating windows.

Default: yes

Note that this option may not work as expected if fractional scaling is being used, due to the fact that many compositors do not report the correct scaling factor until after a window has been mapped.

Default: 700x500.

Note that if you have a multi-monitor setup, with different scaling factors, there is a possibility the window size will not be set correctly. If that is the case, use initial-window-size-pixels instead.

And, just like initial-window-size-pixels, this option may not work as expected if fractional scaling is being used (see initial-window-size-pixels for details).

Default: not set.

If set to palette-based, rather than a simple yes|true, colors matching one of the 8 regular palette colors will be brightened using the corresponding bright palette color. Other colors will not be brightened.

Default: no.

In case you have a ridiculous amount of cores and/or threads, consider limiting the number of workers, since foot cannot parallelize more than the number of visible rows.

When starting foot, an utmp record is created by launching the helper binary with the following arguments:

login $WAYLAND_DISPLAY

When foot is closed, the utmp record is removed by launching the helper binary with the following arguments:

logout

Set to none to disable utmp records. Default: /usr/libexec/ulog-helper.

OSC-52 gives terminal application access to the host clipboard (i.e. the Wayland clipboard). This is normally not a security issue, since all applications can access the clipboard directly over the Wayland socket.

However, when SSH:ing into a remote system, or accessing a container etc, the terminal applications may be untrusted, and you might consider disabling the host clipboard access.

• disabled: disables all clipboard access
• copy-enabled: applications can write to the clipboard, but not read from it.
• paste-enabled: applications can read from the clipboard, but not write to it.
• enabled: all applications have full access to the host clipboard. This is the default.

Default: enabled

Default: yes

If the compositor does not implement this protocol, the margins will be painted in red instead.

Applications can enable/disable this feature programmatically with the CSI ? 1042 h and CSI ? 1042 l escape sequences.

Default: no

Default: no

Template arguments

Ways to trigger notifications

Window activation (focusing)

Stdout

Default: notify-send
--wait
--app-name ${app-id}
--icon ${app-id}
--category ${category}
--urgency ${urgency}
--expire-time ${expire-time}
--hint STRING:image-path:${icon}
--hint BOOLEAN:suppress-sound:${muted}
--hint STRING:sound-name:${sound-name}
--replace-id ${replace-id}
${action-argument}
--print-id
-- ${title} ${body}.

Foot will always configure a "default" action that can be used to "activate" the notification, which in turn can cause the foot window to be focused, or an escape to be sent to the terminal application (depending on how the application generated the notification).

Furthermore, the OSC-99 notifications protocol allows applications to define their own actions. Foot uses a combination of the command option, and the command-action-argument option to pass the names of the actions to the notification helper.

This option has the following template arguments:

• ${action-name}: the name of the action; default for the default action configured by foot, and n, where n is an integer >= 1, for application defined actions.
• ${action-label}: Activate for the default action, and a free-form string for application defined actions.

For each notification action (remember, there will always be at least one), command-action-argument will be expanded with the action's name and label.

Then, ${action-argument} is expanded command to the full list of actions.

If command-action-argument is set to the empty string, no actions will be passed to command. That is, ${action-argument} will be replaced with the empty string.

Example:

command-action-argument=--action ${action-name}=${action-label}
command=notify-send ${action-argument} ...

Assume the application defined two custom actions: OK and Cancel.

Given the above, foot will execute:

Default: --action ${action-name}=${action-label}

${id} is expanded to the ID of the notification that should be closed. For example:

Closing a notification is only supported by the Kitty Desktop Notification protocol, OSC-99.

If set to the empty string (the default), foot will instead try to close the notification by sending SIGINT to the notification helper process. For example, notify-send --wait (libnotify >= 0.8.0) responds to SIGINT by closing the notification.

Default: not set

Default: yes

When set to url-mode, OSC-8 URLs are only highlighted in URL mode, just like auto-detected URLs.

When set to always, OSC-8 URLs are always highlighted, regardless of their other attributes (bold, italic etc). Note that this does not make them clickable.

Default: url-mode

If you change this option to include the letter t, you should also change the default [url-bindings].toggle-url-visible key binding to avoid a clash.

Default: sadfjklewcmpgh.

Default: (((https?://|mailto:|ftp://|file:|ssh:|ssh://|git://|tel:|magnet:|ipfs://|ipns://|gemini://|gopher://|news:)|www.)([0-9a-zA-Z:/?#@!$&*+,;=.~_%^-]+|([]["0-9a-zA-Z:/?#@!$&'*+,;=.~_%^-]*)|[[()"0-9a-zA-Z:/?#@!$&'*+,;=.~_%^-]*]|"[][()0-9a-zA-Z:/?#@!$&'*+,;=.~_%^-]*"|'[][()0-9a-zA-Z:/?#@!$&*+,;=.~_%^-]*')+([0-9a-zA-Z/#@$&*+=~_%^-]|([]["0-9a-zA-Z:/?#@!$&'*+,;=.~_%^-]*)|[[()"0-9a-zA-Z:/?#@!$&'*+,;=.~_%^-]*]|"[][()0-9a-zA-Z:/?#@!$&'*+,;=.~_%^-]*"|'[][()0-9a-zA-Z:/?#@!$&*+,;=.~_%^-]*'))

[regex:hashes]
regex=([a-fA-F0-9]{7,128})
launch=path-to-script-or-application ${match}
[key-bindings]
regex-launch=[hashes] Control+Shift+q
regex-copy=[hashes] Control+Mod1+Shift+q

Default: not set.

• unchanged: render cursor in exactly the same way as when the window has focus.
• hollow: render a block cursor, but hollowed out.
• none: do not display any cursor at all.

Example: ff0000 00ff00 (green cursor, red text)

Default: the regular foreground and background colors, reversed.

To instead specify a thickness in pixels, use the px suffix: e.g. underline-thickness=2px.

Note that if left unset, the cursor's thickness will scale with the font size, while if set, the size is fixed.

Default: font underline thickness.

This lets you scroll with the mouse in e.g. pagers (like less) without enabling native mouse support in them.

Alternate scrolling is not used if the application enables native mouse support.

This option can be modified by applications at run-time using the escape sequences CSI ? 1007 h (enable) and CSI ? 1007 l (disable).

Default: yes.

Default: 400.

By default, foot implements this by blending the current color with black. This is a generic approach that applies to both colors from the 256-color palette, as well as 24-bit RGB colors.

You can change this behavior by setting the dimN options. When set, foot will match the current color against the color palette, and if it matches one of the regularN colors, the corresponding dimN color will be used.

If instead the current color matches one of the brightN colors, the corresponding regularN color will be used.

If the current color does not match any known color, it is dimmed by blending with black (i.e. the same behavior as if the dimN options are unconfigured). 24-bit RGB colors will typically fall into this category.

Note that applications can change the regularN and brightN colors at runtime. However, they have no way of changing the dimN colors. If an application has changed the regularN colors, foot will still use the corresponding dimN color, as configured in foot.ini.

Default: not set.

default applies alpha to cells with the default background color, excluding cells with the same RGB value as the default background color.

matching is the same as default, but also applies alpha to cells with the same RGB value as the default background color.

all applies alpha to all cells, regardless of background color.

Default: default

Note that this is only a hint to the compositor. Depending on compositor support, and how it has been configured, it may instruct foot to use CSDs even though this option has been set to server, or render SSDs despite client or none being set.

Default: server.

You can configure multiple pipes as long as the command strings are different and the key bindings are unique.

Note that the command is not automatically run inside a shell; use sh -c "command line" if you need that.

Example #1:

Example #2:

Default: none

The name of the regex section must be specified in the key binding:

[regex:hashes]
regex=([a-fA-F0-9]{7,128})
launch=path-to-script-or-application ${match}
[key-bindings]
regex-launch=[hashes] Control+Shift+q
regex-copy=[hashes] Control+Mod1+Shift+q

Default: none.

For example, to input the character ö (LATIN SMALL LETTER O WITH DIAERESIS, Unicode codepoint 0xf6), you would first activate this key binding, then type: f, 6, Enter.

Another example: to input 😍 (SMILING FACE WITH HEART-SHAPED EYES, Unicode codepoint 0x1f60d), activate this key binding, then type: 1, f, 6, 0, d, Enter.

Recognized key bindings in Unicode input mode:

• Enter, Space: commit the Unicode character, then exit this mode.
• Escape, q, Ctrl+c, Ctrl+d, Ctrl+g: abort input, then exit this mode.
• 0-9, a-f: append next digit to the Unicode's codepoint.
• Backspace: undo the last digit.

Note that there is no visual feedback while in this mode. This is by design; foot's Unicode input mode is considered to be a fallback. The preferred way of entering Unicode characters, emojis etc is by using an IME.

Default: Control+Shift+u.

But with e.g. OSC-8 URLs (the terminal version of HTML anchors, i.e. "links"), the text on the screen can be something completely different than the URL.

This action toggles between showing and hiding the URL on the jump label.

Default: t.

Alt screen: send fake KeyUP events to the client application, if alternate scroll mode is enabled.

Default: BTN_WHEEL_BACK

Alt screen: send fake KeyDOWN events to the client application, if alternate scroll mode is enabled.

Default: BTN_WHEEL_FORWARD

If a complete quote cannot be found on the current logical row (only one quote character, or none are found), the entire row is selected.

The selection is finalized, and copied to the primary selection, when the button is released.

After the initial selection has been made, it behaves like a normal word, or row selection, depending on whether a quote was found or not. This affects what happens when, for example, extending the selection.

Notes:

• Escaped quote characters are not supported ("foo \"bar" will match 'foo \', not 'foo "bar').
• Foot does not try to handle mismatched quote characters; they will simply not match.
• Nested quotes (using different quote characters) are supported.

Default: BTN_LEFT-3.

Default: lanczos3.

One use case for this are fonts with wide italic characters that "bend" into the next cell. Without this option, such glyphs will appear "cut off".

Another use case are fonts with "icon" characters in the Unicode private usage area, e.g. Nerd Fonts, or Powerline Fonts and legacy emoji characters like WHITE FROWNING FACE.

Note: might impact performance depending on the font used. Especially small font sizes can cause many overflowing glyphs because of subpixel rendering.

Default: yes.

When disabled, they are instead rendered as checker box pattern, using the current foreground color as is.

Default: yes.

If a client splits up a screen update over multiple write(3) calls, we may end up rendering an intermediate frame, quickly followed by another frame with the final screen content. For example, the client may erase part of the screen (or scroll) in one write, and then write new content in one or more subsequent writes. Rendering the frame when the screen has been erased, but not yet filled with new content will be perceived as screen flicker.

The real solution to this is Application Synchronized Updates (https://gitlab.freedesktop.org/terminal-wg/specifications/-/merge_requests/2).

The problem with this is twofold - first, it has not yet been standardized, and thus there are not many terminal emulators that implement it (foot does implement it), and second, applications must be patched to use it.

Until this has happened, foot offers an interim workaround; an attempt to mitigate the screen flicker without affecting neither performance nor latency.

It is based on the fact that the screen is updated at a fixed interval (typically 60Hz). For us, this means it does not matter if we render a new frame at the beginning of a frame interval, or at the end. Thus, the goal is to introduce a delay between receiving client data and rendering the resulting state, but without causing a frame skip.

While it should be possible to estimate the amount of time left until the next frame, foot's algorithm is currently not that advanced, but is based on statistics I guess you could say - the delay we introduce is so small that the risk of pushing the frame over to the next frame interval is also very small.

Now, that was a lot of text. But what is it foot actually does?

When receiving client data, it schedules a timer, the delayed-render-lower. If we do not receive any more client data before the timer has run out, we render the frame. If however, we do receive more data, the timer is re-scheduled. That is, each time we receive client data, frame rendering is delayed another delayed-render-lower nanoseconds.

Now, while this works very well with most clients, it would be possible to construct a malicious client that keeps writing data at a slow pace. To the user, this would look like foot has frozen as we never get to render a new frame. To prevent this, an upper limit is set - delayed-render-upper. If this timer runs out, we render the frame regardless of what the client is doing.

If changing these values, note that the lower timeout must be set lower than the upper timeout, but that this is not verified by foot. Furthermore, both values must be less than 16ms (that is, 16000000 nanoseconds).

You can disable the feature altogether by setting either value to 0. In this case, frames are rendered "as soon as possible".

Default: lower=500000 (0.5ms), upper=8333333 (8.3ms - half a frame interval).

There is normally no reason to enable this. However, it has been seen to workaround an issue with fractional scaling in Gnome.

Note that enabling this option is likely to increase CPU and/or GPU usage (by the compositor, not by foot), and may have a negative impact on battery life.

Default: no.

This is required to render e.g. flag (emoji) sequences, keycap sequences, modifier sequences, zero-width-joiner (ZWJ) sequences and emoji tag sequences. It might also improve rendering of composed characters, depending on font.

This option can also be set runtime with DECSET/DECRST 2027.

See also: grapheme-width-method.

Default: yes

wcswidth simply adds together the individual width of all codepoints making up the cluster.

double-width does the same, but limits the maximum number of columns to 2. This is more correct, but may break some applications since applications typically use wcswidth(3) internally to calculate the width. This results in cursor de-synchronization issues.

max uses the width of the largest codepoint in the cluster.

Default: double-width

Disable this if you still want to use the font, even if foot thinks it is not monospaced.

You may also want to disable it to get slightly faster startup times.

Default: yes

It does not change how much physical memory foot uses.

Foot uses a memory mapping trick to implement fast rendering of interactive scrolling (typically, but applies to "slow" scrolling in general). Example: holding down the 'up' or 'down' arrow key to scroll in a text editor.

For this to work, it needs a large amount of virtual address space. Again, note that this is not physical memory.

On a normal x64 based computer, each process has 128TB of virtual address space, and newer ones have 64PB. This is an insane amount and most applications do not use anywhere near that amount.

Each foot terminal window can allocate up to 2GB of virtual address space. With 128TB of address space, that means a maximum of 65536 windows in server/daemon mode (for 2GB). That should be enough, yes?

However, the Wayland compositor also needs to allocate the same amount of virtual address space. Thus, it has a slightly higher chance of running out of address space since it needs to host all running Wayland clients in the same way, at the same time.

In the off chance that this becomes a problem for you, you can reduce the amount used with this option.

Or, for optimal performance, you can increase it to the maximum allowed value, 2GB (but note that you most likely will not notice any difference compared to the default value).

Setting it to 0 disables the feature.

Limitations:

Default: 512. Maximum allowed: 2048 (2GB).

auto chooses bit depth depending on other settings, and availability.

8-bit, uses 8 bits for each color channel, alpha included. This is the default when gamma-correct-blending=no.

10-bit uses 10 bits for each RGB channel, and 2 bits for the alpha channel. Thus, it provides higher precision color channels, but a lower precision alpha channel. It is the default when gamma-correct-blending=yes, if supported by the compositor.

Note that 10-bit is much slower than 8-bit; if you want to use gamma-correct blending, and if you prefer speed (throughput and input latency) over accurate colors, you can set surface-bit-depth=8-bit explicitly.

Default: auto