foot.ini(5)

NAME

foot.ini - configuration file for foot(1)

DESCRIPTION

foot uses the standard unix configuration format, with section based key/value pairs. The default section is usually unnamed, i.e. not prefixed with a [section]. However it can also be explicitly named [main], say if it needs to be reopened after any of the other sections.

foot will search for a configuration file in the following locations, in this order:

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

An example configuration file containing all options with their default value commented out will usually be installed to /etc/xdg/foot/foot.ini.

Options are set using KEY=VALUE pairs:

    [colors]
    background=000000
    foreground=ffffff

Empty values (KEY=) are not supported. String options do allow the empty string to be set, but it must be quoted: KEY="")

SECTION: main

shell
    Executable to launch. Typically a shell. Default: $SHELL if set, otherwise the user's default shell (as specified in /etc/passwd). You can also pass arguments. For example /bin/bash --norc.

login-shell
    Boolean. If enabled, the shell will be launched as a login shell, by prepending a '-' to argv[0]. Default: no.

term
    Value to set the environment variable TERM to. Default: foot

font, font-bold, font-italic, font-bold-italic
    Comma separated list of fonts to use, in fontconfig format. That is, a font name followed by a list of colon-separated options. Most noteworthy is :size=n (or :pixelsize=n), which is used to set the font size. Note that the font size is also affected by the dpi-aware option.

    Examples:
        •   Dina:weight=bold:slant=italic
        •   Courier New:size=12
        •   Fantasque Sans Mono:fontfeatures=ss01
        •   Iosevka:fontfeatures=cv01=1:fontfeatures=cv06=1
        •   Meslo LG S:size=12, Noto Color Emoji:size=12
        •   Courier New:pixelsize=8

    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).

font-size-adjustment
    Amount, in points, pixels or percent, to increment/decrement the font size when zooming in our out.

    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

include
    Absolute path to configuration file to import.

    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.

        •   The path must be an absolute path, or start with ~/.
        •   Multiple include directives are allowed, but only one path per directive.
        •   Nested imports are allowed.

    Default: not set.

line-height
    An absolute value, in points, that override line height from the font metrics.

    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.

letter-spacing
    Spacing between letters, in points. A positive value will increase the cell size, and a negative value shrinks it.

    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.

horizontal-letter-offset, vertical-letter-offset
    Configure the horizontal and vertical offsets used when positioning glyphs within cells, in points, relative to the top left corner.

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

    Default: 0.

underline-offset
    Use a custom offset for underlines. The offset is, by default, in points and relative the font's baseline. A positive value positions the underline under the baseline, while a negative value positions it above the baseline.

    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.

underline-thickness
    Use a custom thickness (height) for underlines. The thickness is, by default, in points.

    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

strikeout-thickness
    Use a custom thickness (height) for strikeouts. The thickness is, by default, in points.

    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

gamma-correct-blending
    Boolean. When enabled, foot will do gamma-correct blending in linear color space. This is how font glyphs are supposed to be rendered, but since nearly no applications or toolkits are doing it on Linux, the result may not look like you are used to.

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

    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.

    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.

    You may also want to enable 10-bit image buffers when gamma-correct blending is enabled. Though probably only if you do not use a transparent background (with 10-bit buffers, you only get 2 bits alpha). See tweak.surface-bit-depth.

    Default: enabled when compositor support is available

box-drawings-uses-font-glyphs
    Boolean. When disabled, foot generates box/line drawing characters itself. The are several advantages to doing this instead of using font glyphs:

        •   No antialiasing effects where e.g. line endpoints appear dimmed down, or blurred.
        •   Line- and box characters are guaranteed to span the entire cell, resulting in a gap-less appearance.
        •   No alignment issues, i.e. lines are centered when they should be.
        •   Many fonts lack some, or all, of the line- and box drawing characters, causing fallback fonts to be used, which results in out-of-place looking glyphs (for example, badly sized).

    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:

        •   U+02500 - U+0259F
        •   U+02800 - U+028FF
        •   U+1Fb00 - U+1FB9B

    Default: no.

dpi-aware
    Boolean.

    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

pad
    Padding between border and glyphs, in pixels (subject to output scaling), in the form XxY.

    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.

resize-delay-ms

    Time, in milliseconds, of "idle time" before foot performs text reflow, and sends the new window dimensions to the client application while doing an interactive resize of a foot window. Idle time in this context is a period of time where the window size is not changing.

    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.

resize-by-cells
    Boolean.

    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

resize-keep-grid
    Boolean.

    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

initial-window-size-pixels
    Initial window width and height in pixels (subject to output scaling), in the form WIDTHxHEIGHT. The height includes the titlebar when using CSDs. Mutually exclusive to initial-window-size-chars.

    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.

initial-window-size-chars
    Initial window width and height in characters, in the form WIDTHxHEIGHT. Mutually exclusive to initial-window-size-pixels.'

    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.

initial-window-mode
    Initial window mode for each newly spawned window: windowed, maximized or fullscreen. Default: windowed.

title
    Initial window title. Default: foot.

locked-title
    Boolean. If enabled, applications are not allowed to change the title at run-time. Default: no.

app-id
    Value to set the app-id property on the Wayland window to. The compositor can use this value to e.g. group multiple windows, or apply window management rules. Default: foot (normal mode), or footclient (server mode).

bold-text-in-bright
    Semi-boolean. When enabled, bold text is rendered in a brighter color (in addition to using a bold font). The color is brightened by increasing its luminance.

    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.

word-delimiters
    String of characters that act as word delimiters when selecting text. Note that whitespace characters are always word delimiters, regardless of this setting. Default: ,│`|:"'()[]{}<>

selection-target
    Clipboard target to automatically copy selected text to. One of none, primary, clipboard or both. Default: primary.

workers
    Number of threads to use for rendering. Set to 0 to disable multithreading. Default: the number of available logical CPUs (including SMT). Note that this is not always the best value. In some cases, the number of physical cores is better.

utmp-helper
    Path to utmp logging helper binary.

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

        add $WAYLAND_DISPLAY

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

        del

    Set to none to disable utmp records. Default: /usr/lib/aarch64-linux-gnu/utempter/utempter.

SECTION: environment

This section is used to define environment variables that will be set in the client application, in addition to the variables inherited from the terminal process itself.

The format is simply:

name=value

Note: do not set TERM here; use the term option in the main (default) section instead.

SECTION: security

osc52

    Whether OSC-52 (clipboard access) is enabled or disabled. One of disabled, copy-enabled, paste-enabled or enabled.

    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

SECTION: bell

system
    Boolean, when set to yes, ring the system bell. The bell is rung independent of whether the foot window has keyboard focus or not. Exact behavior is compositor dependent.

    Default: yes

urgent
    Boolean, when set to yes, foot will signal urgency to the compositor through the XDG activation protocol whenever BEL is received, and the window does NOT have keyboard focus.

    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

notify
    Boolean, when set to yes, foot will emit a desktop notification using the command specified in the notify option whenever BEL is received. By default, bell notifications are shown only when the window does not have keyboard focus. See desktop-notifications.inhibit-when-focused.

    Default: no

visual
    Boolean, when set to yes, foot will flash the terminal window. Default: no

command
    When set, foot will execute this command when BEL is received. Default: none

command-focused
    Boolean, whether to run the command on BEL even while focused. Default: no

SECTION: desktop-notifications

command
    Command to execute to display a notification.

    Template arguments
        ${title} and ${body} will be replaced with the notification's actual title and body (message content).

        ${app-id} is replaced with the value of the command line option --app-id, and defaults to foot (normal mode), or footclient (server mode).

        ${window-title} is replaced with the current window title.

        ${icon} is replaced by the icon specified in the notification request, or the empty string if no icon was specified. Can be used with e.g. notify-send's --icon option, or preferably, by setting the image-path hint (with e.g. notify-send's --hint option).

        ${category} is replaced by the notification's catogory. Can be used together with e.g. notify-send's --category option.

        ${urgency} is replaced with the notifications urgency; low, normal or critical. Can be used together with e.g. notify-send's --urgency option.

        ${expire-time} is replaced with the notification specified notification timeout. Can be used together with e.g. notify-send's --expire-time option.

        ${replace-id} is replaced by the notification daemon assigned ID that the notification replaces/updates. For this to work, foot needs to know the externally assigned IDs of previously emitted notifications, see the 'stdout' section below. Can be used together with e.g. notify-send's --replace-id option.

        ${muted} is replaced by either true or false, depending on whether the notification has requested all notification sounds be muted. It is intended to set the suppress-sound hint (with e.g. notify-send's --hint option).

        ${sound-name} is replaced by sound-name requested by the notification. This should be a name from the freedesktop sound naming specification, but this is not something that foot enforces. It is intended to set the sound-name hint (with e.g. notify-send's --hint option).

        ${action-argument} will be expanded to the command-action-argument option, for each notification action. There will always be at least one action, the "default" action. Foot uses this to enable window focusing, and reporting notification activation to applications that requested such events.

        Applications can also define their own custom notification actions. See the command-action-argument option for details.

    Ways to trigger notifications
        Applications can trigger notifications in the following ways:

        •   OSC 777: \e]777;notify;<title>;<body>\e\\
        •   OSC 99: \e]99;;<title>\e\\ (this is just a bare bones example; this protocol has lots of features, see https://sw.kovidgoyal.net/kitty/desktop-notifications)

        By default, notifications are inhibited if the foot window has keyboard focus. See desktop-notifications.inhibit-when-focused.

    Window activation (focusing)
        Foot can focus the window when the notification is 'activated'. It can also send an event back to the client application, notifying it that the notification has been 'activated', This typically happens when the default action is invoked, and/or when the notification is clicked, but exact behavior depends on the notification daemon in use, and how it has been configured.

        For this to work, foot needs to know when the notification was activated (as opposed to just dismissed), and it needs an XDG activation token.

        There are two parts to handle this. First, the notification must define an action. For this purpose, foot will add a "default" action to the notification (see the command-action-argument option).

        Second, foot needs to know when the notification is activated, and it needs to get hold of the XDG activation token.

        Both are expected to be printed on stdout.

        Foot expects the action name (not label) to be printed on a single line. No prefix, no postfix.

        Foot expects the activation token to be printed on a single line, prefixed with xdgtoken=.

        Example:
            default
            xdgtoken=18179adf579a7a904ce73754964b1ec3

        The expected format of stdout may change at any time. Please read the changelog when upgrading foot.

        Note: notify-send does not, out of the box, support reporting the XDG activation token in any way. This means window activation will not work by default.

    Stdout
        Foot recognizes the following things from the notification helper's stdout:

        •   id: integer in base 10, daemon assigned notification ID
        •   id=id: same as plain nnn.
        •   default: the 'default' action was triggered
        •   action=default: same as default
        •   action=n: application custom action n triggered
        •   n: integer in base 10, appearing after the ID; application custom action n triggered
        •   xdgtoken=xyz: XDG activation token.

        Example #1:
            17
            action=default
            xdgtoken=95ebdfe56e4f47ddb5bba9d7dc3a2c35

            Foot recognizes this as:
            •   notification has the daemon assigned ID 17
            •   the user triggered the default action
            •   the notification send an XDG activation token

        Example #2:
            17
            1

            Foot recognizes this as:
            •   notification has the daemon assigned ID 17
            •   the user triggered the first custom action, "1"

        Example #3:
            id=17
            1

            Foot recognizes this as:
            •   notification has the daemon assigned ID 17
            •   the user triggered the first custom action, "1

    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}.

command-action-argument
    String to use with command to enable passing action/button names to the notification helper.

    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:

        notify-send
                    --action default='Click to activate'
                    --action 1=OK
                    --action 2=Cancel
                    ...

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

close
    Command to execute to close an existing notification.

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

        fyi --close ${id}

    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

inhibit-when-focused
    Boolean. If enabled, foot will not display notifications if the terminal window has keyboard focus.

    Default: yes

SECTION: scrollback

lines
    Number of scrollback lines. The maximum number of allocated lines will be this value plus the number of visible lines, rounded up to the nearest power of 2. Default: 1000.

multiplier
    Amount to multiply mouse scrolling with. It is a decimal number, i.e. fractions are allowed. Default: 3.0.

indicator-position
    Configures the style of the scrollback position indicator. One of none, fixed or relative. none disables the indicator completely. fixed always renders the indicator near the top of the window, and relative renders the indicator at the position corresponding to the current scrollback position. Default: relative.

indicator-format
    Which format to use when displaying the scrollback position indicator. Either percentage, line, or a custom fixed string. This option is ignored if indicator-position=none. Default: empty string.

SECTION: url

Note that you can also add custom regular expressions, see the 'regex' section.

launch
    Command to execute when opening URLs. ${url} will be replaced with the actual URL. Default: xdg-open ${url}.

osc8-underline
    When to underline OSC-8 URLs. Possible values are url-mode and always.

    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

label-letters
    String of characters to use when generating key sequences for URL jump labels.

    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.

regex
    Regular expression to use when auto-detecting URLs. The format is "POSIX-Extended Regular Expressions". Note that the first marked subexpression is used as the URL. In other words, if you want the whole regex match to be used as an URL, surround all of it with parenthesis: (regex-pattern).

    Default: (([a-z][[:alnum:]-]+:(/{1,3}|[a-z0-9%])|www[:digit:]{0,3}[.])([^[:space:](){}<>]+|(([^[:space:](){}<>]+|(([^[:space:](){}<>]+)))*)|[([^][[:space:](){}<>]+|([[^][[:space:](){}<>]+]))*])+((([^[:space:](){}<>]+|(([^[:space:](){}<>]+)))*)|[([^][[:space:](){}<>]+|([[^][[:space:](){}<>]+]))*]|[^][[:space:]`!(){};:'".,<>?«»“”‘’]))

SECTION: regex

Similar to the 'url' mode, but with custom defined regular expressions (and launchers).

To use a custom defined regular expression, you also need to add a key binding for it. This is done in the key-binding section, see below for details. For example, a regex to detect hash digests (e.g. git commit hashes) could look like:

    [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

launch
    Command to execute when "launching" a regex match. ${match} will be replaced with the actual URL. Default: not set.

regex
    Regular expression to use when matching text. The format is "POSIX-Extended Regular Expressions". Note that the first marked subexpression is used as the match. In other words, if you want the whole regex match to be used, surround all of it with parenthesis: (regex-pattern).

    Default: not set.

SECTION: cursor

This section controls the cursor style and color. Note that applications can change these at runtime.

style
    Configures the default cursor style, and is one of: block, beam, underline or hollow. Note that this can be overridden by applications. Default: block.

unfocused-style
    Configures how the cursor is rendered when the terminal window is unfocused. Possible values are:

    •   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.

blink
    Boolean. Enables blinking cursor. Note that this can be overridden by applications. Related option: blink-rate. Default: no.

blink-rate
    The rate at which the cursor blink, when cursor blinking has been enabled. Expressed in milliseconds between each blink. Default: 500.

color
    Two space separated RRGGBB values (i.e. plain old 6-digit hex values, without prefix) specifying the foreground (text) and background (cursor) colors for the cursor.

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

    Default: the regular foreground and background colors, reversed.

beam-thickness
    Thickness (width) of the beam styled cursor. The value is in points, and its exact value thus depends on the monitor's DPI. To instead specify a thickness in pixels, use the px suffix: e.g. beam-thickness=2px. Default: 1.5

underline-thickness
    Thickness (height) of the underline styled cursor. The value is in points, and its exact value thus depends on the monitor's DPI.

    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.

SECTION: mouse

hide-when-typing
    Boolean. When enabled, the mouse cursor is hidden while typing. Default: no.

alternate-scroll-mode
    Boolean. This option controls the initial value for the alternate scroll mode. When this mode is enabled, mouse scroll events are translated to up/down key events when displaying the alternate screen.

    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.

SECTION: touch

long-press-delay
    Number of milliseconds to distinguish between a short press and a long press on the touchscreen.

    Default: 400.

SECTION: colors

This section controls the 16 ANSI colors, the default foreground and background colors, and the extended 256 color palette. Note that applications can change these at runtime.

The colors are in RRGGBB format (i.e. plain old 6-digit hex values, without prefix). That is, they do not have an alpha component. You can configure the background transparency with the alpha option.

foreground
    Default foreground color. This is the color used when no ANSI color is being used. Default: 839496.

background
    Default background color. This is the color used when no ANSI color is being used. Default: 002b36.

regular0, regular1 .. regular7
    The eight basic ANSI colors (Black, Red, Green, Yellow, Blue, Magenta, Cyan, White). Default: 242424, f62b5a, 47b413, e3c401, 24acd4, f2affd, 13c299, e6e6e6 (starlight theme, V4).

bright0, bright1 .. bright7
    The eight bright ANSI colors (Black, Red, Green, Yellow, Blue, Magenta, Cyan, White). Default: 616161, ff4d51, 35d450, e9e836, 5dc5f8, feabf2, 24dfc4, ffffff (starlight theme, V4).

dim0, dim1 .. dim7
    Custom colors to use with dimmed colors. Dimmed colors do not have an entry in the color palette. Applications emit them by combining a color value, and a "dim" attribute.

    By default, foot implements this by reducing the luminance of the current color. 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 reducing the luminance (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.

0 .. 255
    Arbitrary colors in the 256-color palette. Default: for 0 .. 15, see regular and bright defaults above; see https://en.wikipedia.org/wiki/ANSI_escape_code#8-bit for an explanation of the remainder.

sixel0 .. sixel15
    The default sixel color palette. Default: 000000, 3333cc, cc2121, 33cc33, cc33cc, 33cccc, cccc33, 878787, 424242, 545499, 994242, 549954, 995499, 549999, 999954, cccccc.

alpha
    Background translucency. A value in the range 0.0-1.0, where 0.0 means completely transparent, and 1.0 is opaque. Default: 1.0.

selection-foreground, selection-background
    Foreground (text) and background color to use in selected text. Note that both options must be set, or the default will be used. Default: inverse foreground/background.

jump-labels
    Two color values specifying the foreground (text) and background colors to use when rendering jump labels in URL mode. Default: regular0 regular3.

scrollback-indicator
    Two color values specifying the foreground (text) and background (indicator itself) colors for the scrollback indicator. Default: regular0 bright4.

search-box-no-match
    Two color values specifying the foreground (text) and background colors for the scrollback search box, when there are no matches. Default: regular0 regular1.

search-box-match
    Two color values specifying the foreground (text) and background colors for the scrollback search box, when the search box is either empty, or there are matches. Default: regular0 regular3.

urls
    Color to use for the underline used to highlight URLs in URL mode. Default: regular3.

flash
    Color to use for the terminal window flash. Default: 7f7f00.

flash-alpha
    Flash translucency. A value in the range 0.0-1.0, where 0.0 means completely transparent, and 1.0 is opaque. Default: 0.5.

SECTION: csd

This section controls the look of the CSDs (Client Side Decorations). Note that the default is to not use CSDs, but instead to use SSDs (Server Side Decorations) when the compositor supports it.

Note that unlike the colors defined in the colors section, the color values here are in AARRGGBB (i.e. plain old 8-digit hex values) format. I.e. they contain an alpha component - 00 means completely transparent, and ff fully opaque.

Examples:

•   ffffffff: white, fully opaque
•   ff000000: black, fully opaque
•   7fffffff: white, semi-transparent
•   ff00ff00: green, fully opaque

preferred
    Which type of window decorations to prefer: client (CSD), server (SSD) or none.

    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.

size
    Height, in pixels (subject to output scaling), of the titlebar. Setting it to 0 will hide the titlebar, while still showing the border (if border-width is set to a non-zero value). Default: 26.

color
    Titlebar color. Default: use the default foreground color.

font
    Font to use for the title bar. This is a list of fonts, similar to the main font option. Note that the font will be sized using the title bar size. That is, all :size and :pixelsize attributes will be ignored. Default: primary font.

hide-when-maximized
    Boolean. When enabled, the CSD titlebar is hidden when the window is maximized. The completely disable the titlebar, set size to 0 instead. Default: no.

double-click-to-maximize
    Boolean. When enabled, double-clicking the CSD titlebar will (un)maximize the window. Default: yes.

border-width
    Width of the border, in pixels (subject to output scaling). Note that the border encompasses the entire window, including the title bar. Default: 0.

border-color
    Color of border. By default, the title bar color is used. If the title bar color has not been set, the default foreground color (from the color scheme) is used. Default: titlebar color.

button-width
    Width, in pixels (subject to output scaling), of the minimize/maximize/close buttons. Default: 26.

button-color
    Foreground color on the minimize/maximize/close buttons. Default: use the default background color.

button-minimize-color
    Minimize button's background color. Default: use the default regular4 color (blue).

button-maximize-color
    Maximize button's background color. Default: use the default regular2 color (green).

button-close-color
    Close button's background color. Default: use the default regular1 color (red).

SECTION: key-bindings

This section lets you override the default key bindings.

The general format is action=combo1...comboN. That is, each action may have one or more key combinations, space separated. Each combination is in the form mod1+mod2+key. The names of the modifiers and the key must be valid XKB key names.

Note that if Shift is one of the modifiers, the key must not be in upper case. For example, Control+Shift+V will never trigger, but Control+Shift+v will.

Note that Alt is usually called Mod1.

xkbcli interactive-wayland can be useful for finding keysym names.

When matching key presses to key bindings, foot uses a couple of different approaches.

As an example, let's say you press ctrl+shift+c (assume plain us ASCII layout). XKB will tell foot Control+C was pressed. Note the lack of the shift modifier, and the upper case 'C'. Internally, this is called the "translated" form, and is what foot tries to match first.

If no "translated" key bindings can be found, foot proceeds to checking the "untranslated" variant. Using the same example as above, this will match Control+Shift+c (shift modifier present, lower case 'c').

This means you can use either form in your foot configuration, and that Control+C (and similar) has higher priority than Control+Shift+c. Also note that while foot normally detects when the same combination is assigned to multiple actions, it will not detect Control+C vs. Control+Shift+c collisions. Call it a known bug...

Finally, foot tries to match the raw key code. Here, the primary layout is queried for all key codes that generate a particular XKB symbol, and the pressed key's code is matched against this. For example, if you use the layouts "us,de(neo)", the 'r' key generates the symbol 'c' in the neo layout. I.e. to get a 'c', you press 'r'. The match logic described above will only match 'c' key bindings (e.g. Control+Shift+c). The raw mode however, will match 'r' key bindings (e.g. Control+Shift+r). This is useful for non-latin layouts, where you would otherwise have to customize all key bindings.

A key combination can only be mapped to one action. Let's say you want to bind Control+Shift+R to fullscreen. Since this is the default shortcut for search-start, you first need to unmap the default binding. This can be done by setting action=none; e.g. search-start=none.

noop
    All key combinations listed here will not be sent to the application. Default: none.

scrollback-up-page
    Scrolls up/back one page in history. Default: Shift+Page_Up Shift+KP_Page_Up.

scrollback-up-half-page
    Scrolls up/back half of a page in history. Default: none.

scrollback-up-line
    Scrolls up/back a single line in history. Default: none.

scrollback-down-page
    Scroll down/forward one page in history. Default: Shift+Page_Down Shift+KP_Page_Down.

scrollback-down-half-page
    Scroll down/forward half of a page in history. Default: none.

scrollback-down-line
    Scroll down/forward a single line in history. Default: none.

scrollback-home
    Scroll to the beginning of the scrollback. Default: none.

scrollback-end
    Scroll to the end (bottom) of the scrollback. Default: none.

clipboard-copy
    Copies the current selection into the clipboard. Default: Control+Shift+c XF86Copy.

clipboard-paste
    Pastes from the clipboard. Default: Control+Shift+v XF86Paste.

primary-paste
    Pastes from the primary selection. Default: Shift+Insert (also defined in mouse-bindings).

search-start
    Starts a scrollback/history search. Default: Control+Shift+r.

font-increase
    Increases the font size by 0.5pt. Default: Control+plus Control+equal Control+KP_Add (also defined in mouse-bindings).

font-decrease
    Decreases the font size by 0.5pt. Default: Control+minus Control+KP_Subtract (also defined in mouse-bindings).

font-reset
    Resets the font size to the default. Default: Control+0 Control+KP_0.

spawn-terminal
    Spawns 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. Default: Control+Shift+n.

minimize
    Minimizes the window. Default: none.

maximize
    Toggle the maximized state. Default: none.

fullscreen
    Toggles the fullscreen state. Default: none.

pipe-visible, pipe-scrollback, pipe-selected, pipe-command-output
    Pipes the currently visible text, the entire scrollback, the currently selected text, or the last command's output to an external tool. The syntax for this option is a bit special; the first part of the value is the command to execute enclosed in "[]", followed by the binding(s).

    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:
        # Extract currently visible URLs, let user choose one (via fuzzel), then launch firefox with the selected URL
        pipe-visible=[sh -c "xurls | uniq | tac | fuzzel | xargs -r firefox"] Control+Print

    Example #2:
        # Open scrollback contents in Emacs running in a new foot instance
        pipe-scrollback=[sh -c "f=$(mktemp) && cat - > $f && foot emacsclient -t $f; rm $f"] Control+Shift+Print

    Default: none

show-urls-launch
    Enter URL mode, where all currently visible URLs are tagged with a jump label with a key sequence that will open the URL (and exit URL mode). Default: Control+Shift+o.

show-urls-persistent
    Similar to show-urls-launch, but does not automatically exit URL mode after activating an URL. Default: none.

show-urls-copy
    Enter URL mode, where all currently visible URLs are tagged with a jump label with a key sequence that will place the URL in the clipboard. Default: none.

regex-launch
    Enter regex mode. This works exactly the same as URL mode; all regex matches are tagged with a jump label with a key sequence that will "launch" to match (and exit regex mode).

    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.

regex-copy
    Same as regex-copy, but the match is placed in the clipboard, instead of "launched", upon activation. Default: none.

prompt-prev
    Jump to the previous, currently not visible, prompt (requires shell integration, see foot(1)). Default: Control+Shift+z.

prompt-next
    Jump the next prompt (requires shell integration, see foot(1)). Default: Control+Shift+x.

unicode-input
    Input a Unicode character by typing its codepoint in hexadecimal, followed by Enter or Space.

    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.

quit
    Quit foot. Default: none.

SECTION: search-bindings

This section lets you override the default key bindings used in scrollback search mode. The syntax is exactly the same as the regular key-bindings.

cancel
    Aborts the search. The viewport is restored and the primary selection is not updated. Default: Control+g Control+c Escape.

commit
    Exit search mode and copy current selection into the primary selection. Viewport is not restored. To copy the selection to the regular clipboard, use Control+Shift+c. Default: Return KP_Enter.

find-prev
    Search backwards in the scrollback history for the next match. Default: Control+r.

find-next
    Searches forwards in the scrollback history for the next match. Default: Control+s.

cursor-left
    Moves the cursor in the search box one character to the left. Default: Left Control+b.

cursor-left-word
    Moves the cursor in the search box one word to the left. Default: Control+Left Mod1+b.

cursor-right
    Moves the cursor in the search box one character to the right. Default: Right Control+f.

cursor-right-word
    Moves the cursor in the search box one word to the right. Default: Control+Right Mod1+f.

cursor-home
    Moves the cursor in the search box to the beginning of the input. Default: Home Control+a.

cursor-end
    Moves the cursor in the search box to the end of the input. Default: End Control+e.

delete-prev
    Deletes the character before the cursor. Default: BackSpace.

delete-prev-word
    Deletes the word before the cursor. Default: Mod1+BackSpace Control+BackSpace.

delete-next
    Deletes the character after the cursor. Default: Delete.

delete-next-word
    Deletes the word after the cursor. Default: Mod1+d Control+Delete.

delete-to-start
    Deletes search input before the cursor. Default: Ctrl+u.

delete-to-end
    Deletes search input after the cursor. Default: Ctrl+k.

extend-char
    Extend current selection to the right, by one character. Default: Shift+Right.

extend-to-word-boundary
    Extend current selection to the right, to the next word boundary. Default: Control+w Control+Shift+Right.

extend-to-next-whitespace
    Extend the current selection to the right, to the next whitespace. Default: Control+Shift+w.

extend-line-down
    Extend current selection down one line. Default: Shift+Down.

extend-backward-char
    Extend current selection to the left, by one character. Default: Shift+Left.

extend-backward-to-word-boundary
    Extend current selection to the left, to the next word boundary. Default: Control+Shift+Left.

extend-backward-to-next-whitespace
    Extend the current selection to the left, to the next whitespace. Default: none.

extend-line-up
    Extend current selection up one line. Default: Shift+Up.

clipboard-paste
    Paste from the clipboard into the search buffer. Default: Control+v Control+y Control+Shift+v XF86Paste.

primary-paste
    Paste from the primary selection into the search buffer. Default: Shift+Insert.

unicode-input
    Unicode input mode. See key-bindings.unicode-input for details. Default: none.

scrollback-up-page
    Scrolls up/back one page in history. Default: Shift+Page_Up Shift+KP_Page_Up.

scrollback-up-half-page
    Scrolls up/back half of a page in history. Default: none.

scrollback-up-line
    Scrolls up/back a single line in history. Default: none.

scrollback-down-page
    Scroll down/forward one page in history. Default: Shift+Page_Down Shift+KP_Page_Down.

scrollback-down-half-page
    Scroll down/forward half of a page in history. Default: none.

scrollback-down-line
    Scroll down/forward a single line in history. Default: none.

scrollback-home
    Scroll to the beginning of the scrollback. Default: none.

scrollback-end
    Scroll to the end (bottom) of the scrollback. Default: none.

SECTION: url-bindings

This section lets you override the default key bindings used in URL mode. The syntax is exactly the same as the regular key-bindings.

Be careful; do not use single-letter keys that are also used in [url].label-letters, as doing so will make some URLs inaccessible.

cancel
    Exits URL mode without opening a URL. Default: Control+g Control+c Control+d Escape.

toggle-url-visible
    By default, the jump label only shows the key sequence required to activate it. This is fine as long as the URL is visible in the original text.

    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.

SECTION: text-bindings

This section lets you remap key combinations to custom escape sequences.

The format is text=combo1...comboN. That is, the string to emit may have one or more key combinations, space separated. Each combination is in the form mod1+mod2+key. The names of the modifiers and the key must be valid XKB key names.

The text string specifies the characters, or bytes, to emit when the associated key combination(s) are pressed. There are two ways to specify a character:

•   Normal, printable characters are written as-is: abcdef.
•   Bytes (e.g. ESC) are written as two-digit hexadecimal numbers, with a \x prefix: \x1b.

Example: you would like to remap Super+k to the Up key.

The escape sequence for the Up key is ESC [ A (without the spaces). Thus, we need to specify this in foot.ini (Mod4 is the XKB name for the Super/logo key):

\x1b[A = Mod4+k

Another example: to remap Super+c to Control+c:

\x03 = Mod4+c

SECTION: mouse-bindings

This section lets you override the default mouse bindings.

The general format is action=combo1...comboN. That is, each action may have one or more key combinations, space separated. Each combination is in the form mod1+mod2+BTN_<name>[-COUNT]. The names of the modifiers must be valid XKB key names, and the button name must be a valid libinput name. You can find the button names using libinput debug-events.

The trailing COUNT (number of times the button has to be clicked) is optional and specifies the click count required to trigger the binding. The default if COUNT is omitted is 1.

To map wheel events (i.e. scrolling), use the button names BTN_WHEEL_BACK (up) and BTN_WHEEL_FORWARD (down). Note that these events never generate a COUNT larger than 1. That is, BTN_WHEEL_BACK+2, for example, will never trigger.

Foot also recognizes tiltable wheels; to map these, use BTN_WHEEL_LEFT and BTN_WHEEL_RIGHT.

A modifier+button combination can only be mapped to one action. Let's say you want to bind BTN_MIDDLE to fullscreen. Since BTN_MIDDLE is the default binding for primary-paste, you first need to unmap the default binding. This can be done by setting action=none; e.g. primary-paste=none.

selection-override-modifiers
    The modifiers set in this set (which may be set to any combination of modifiers, e.g. mod1+mod2+mod3, as well as none) are used to enable selecting text with the mouse irrespective of whether a client application currently has the mouse grabbed. These modifiers cannot be used as modifiers in mouse bindings. Because the order of bindings is significant, it is best to set this prior to any other mouse bindings that might use modifiers in the default set. Default: Shift

The actions to which mouse combos can be bound are listed below. All actions listed under key-bindings can be used here as well.

scrollback-up-mouse
    Normal screen: scrolls up the contents.

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

    Default: BTN_WHEEL_BACK

scrollback-down-mouse
    Normal screen: scrolls down the contents.

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

    Default: BTN_WHEEL_FORWARD

select-begin
    Begin an interactive selection. The selection is finalized, and copied to the primary selection, when the button is released. Default: BTN_LEFT.

select-begin-block
    Begin an interactive block selection. The selection is finalized, and copied to the primary selection, when the button is released. Default: Control+BTN_LEFT.

select-word
    Begin an interactive word-wise selection, where words are separated by whitespace and all characters defined by the word-delimiters option. The selection is finalized, and copied to the primary selection, when the button is released. Default: BTN_LEFT-2.

select-word-whitespace
    Same as select-word, but the characters in the word-delimiters option are ignored. I.e only whitespace characters act as delimiters. The selection is finalized, and copied to the primary selection, when the button is released. Default: Control+BTN_LEFT-2.

select-quote
    Begin an interactive "quote" selection. This is similar to select-word, except an entire quote is selected (that is, everything inside the quote, excluding the quote characters). Recognized quote characters are: " and '.

    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.

select-row
    Begin an interactive row-wise selection. The selection is finalized, and copied to the primary selection, when the button is released. Default: BTN_LEFT-4.

select-extend
    Interactively extend an existing selection, using the original selection mode (normal, block, word-wise or row-wise). The selection is finalized, and copied to the primary selection, when the button is released. Default: BTN_RIGHT.

select-extend-character-wise
    Same as select-extend, but forces the selection mode to normal (i.e. character wise). Note that this causes subsequent select-extend operations to be character wise. This action is ignored for block selections. Default: Control+BTN_RIGHT.

primary-paste
    Pastes from the primary selection. Default: BTN_MIDDLE.

font-increase
    Increases the font size by 0.5pt. Default: Control+BTN_WHEEL_BACK (also defined in key-bindings).

font-decrease
    Decreases the font size by 0.5pt. Default: Control+BTN_WHEEL_FORWARD (also defined in key-bindings).

TWEAK

This section is for advanced users and describes configuration options that can be used to tweak foot's low-level behavior.

These options are not included in the example configuration. You should not change these unless you understand what they do.

Note that these options may change, or be removed at any time, without prior notice.

When reporting bugs, please mention if, and to what, you have changed any of these options.

scaling-filter
    Overrides the default scaling filter used when down-scaling bitmap fonts (e.g. emoji fonts). Possible values are none, nearest, bilinear, impulse, box, linear, cubic gaussian, lanczos2, lanczos3 or lanczos3-stretched.

    Default: lanczos3.

overflowing-glyphs
    Boolean. When enabled, glyphs wider than their cell(s) are allowed to render into one additional neighbouring cell.

    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.

render-timer
    Enables a frame rendering timer, that prints the time it takes to render each frame, in microseconds, either on-screen, to stderr, or both. Valid values are none, osd, log and both. Default: none.

box-drawing-base-thickness
    Line thickness to use for LIGHT box drawing line characters, in points. This value is converted to pixels using the monitor's DPI, and then multiplied with the cell size. The end result is that a larger font (and thus larger cells) result in thicker lines. Default: 0.04.

box-drawing-solid-shades
    Boolean. When enabled, box drawing "shades" (e.g. LIGHT SHADE, MEDIUM SHADE and DARK SHADE) are rendered as solid blocks using a darker variant of the current foreground color.

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

    Default: yes.

delayed-render-lower, delayed-render-upper
    These two values control the timeouts (in nanoseconds) that are used to mitigate screen flicker caused by clients writing large, non-atomic screen updates.

    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).

damage-whole-window
    Boolean. When enabled, foot will 'damage' the entire window each time a frame has been rendered. This forces the compositor to redraw the entire window. If disabled, foot will only 'damage' updated rows.

    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.

grapheme-shaping
    Boolean. When enabled, foot will use utf8proc to do grapheme cluster segmentation while parsing "printed" text. Then, when rendering, it will use fcft (if compiled with HarfBuzz support) to shape the grapheme clusters.

    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.

        •   foot must have been compiled with utf8proc support
        •   fcft must have been compiled with HarfBuzz support

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

    See also: grapheme-width-method.

    Default: yes

grapheme-width-method
    Selects which method to use when calculating the width (i.e. number of columns) of a grapheme cluster. One of wcswidth, double-width and max.

    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

font-monospace-warn
    Boolean. When enabled, foot will use heuristics to try to verify the primary font is a monospace font, and warn if it is not.

    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

max-shm-pool-size-mb
    This option controls the amount of virtual address space used by the pixmap memory to which the terminal screen content is rendered.

    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:
        •   only supported on 64-bit architectures
        •   only supported on Linux

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

sixel
    Boolean. When enabled, foot will process sixel images. Default: yes

bold-text-in-bright-amount
    Amount by which bold fonts are brightened when bold-text-in-bright is set to yes (the palette-based variant is not affected by this option). Default: 1.3.

surface-bit-depth
    Selects which RGB bit depth to use for image buffers. One of 8-bit, or 10-bit.

    The default, 8-bit, uses 8 bits for all channels, alpha included. When gamma-correct-blending is disabled, this is the best option.

    When gamma-correct-blending is enabled, you may want to enable 10-bit surfaces, as that improves the color resolution. Be aware however, that in this mode, the alpha channel is only 2 bits instead of 8 bits. Thus, if you are using a transparent background, you may want to use the default, 8-bit, even if you have gamma-correct blending enabled.

    You should also note that 10-bit surface is slower. This will increase input latency and decrease rendering throughput.

    Default: 8-bit

SEE ALSO

foot(1), footclient(1)