eww Documentation

File: README.md Copy Chapter

Eww

Elkowars Wacky Widgets is a standalone widget system made in Rust that allows you to implement
your own, custom widgets in any window manager.

Documentation and instructions on how to install can be found here.

Dharmx also wrote a nice, beginner friendly introductory guide for eww here.

Check out another cool project by me Copy Chapter

I'm currently busy working yolk,
which is a dotfile management solution that supports a unique spin on templating: templating without template files.

To find out more, check out the website and documentation!

Examples Copy Chapter

(Note that some of these still make use of the old configuration syntax.)

• A basic bar, see examples

• Some setups by Druskus20

• My own vertical bar

• Vertical Bar by Rxyhn

• Setup by Axarva

• Setup by adi1090x

• i3 Bar replacement by owenrumney

• Setups by iSparsh

• topbar by saimoomedits

• Activate Linux by Nycta

Contribewwting Copy Chapter

If you want to contribute anything, like adding new widgets, features, or subcommands (including sample configs), you should definitely do so.

Steps Copy Section

1. Fork this repository
2. Install dependencies
3. Smash your head against the keyboard from frustration (coding is hard)
4. Write down your changes in CHANGELOG.md
5. Open a pull request once you're finished

Widget Copy Chapter

https://en.wikipedia.org/wiki/Wikipedia:Widget

File: crates/simplexpr/README.md Copy Chapter

simplexpr

simplexpr is a parser and interpreter for a simple expression syntax that can be embedded into other applications or crates.
It is being developed to be used in eww, but may also other uses.

For now, this is highly experimental, unstable, and ugly. You most definitely do not want to use this crate.

File: docs/src/configuration.md Copy Chapter

Writing your eww configuration

(For a list of all built-in widgets (i.e. box, label, button), see Widget Documentation.)
Eww is configured using its own language called yuck.
Using yuck, you declare the structure and content of your widgets, the geometry, position, and behavior of any windows,
as well as any state and data that will be used in your widgets.
Yuck is based around S-expressions, which you may know from lisp-like languages.
If you're using vim, you can make use of yuck.vim for editor support.
If you're using VSCode, you can get syntax highlighting and formatting from yuck-vscode.
It is also recommended to use parinfer,
which makes working with S-expressions delightfully easy!

Additionally, any styles are defined in CSS or SCSS (which is mostly just slightly improved CSS syntax).
While eww supports a significant portion of the CSS you know from the web,
not everything is supported, as eww relies on GTK's own CSS engine.
Notably, some animation features are unsupported,
as well as most layout-related CSS properties such as flexbox, float, absolute position or width/height.

To get started, you'll need to create two files: eww.yuck and eww.scss (or eww.css, if you prefer).
These files must be placed under $XDG_CONFIG_HOME/eww (this is most likely ~/.config/eww).

Now that those files are created, you can start writing your first widget!

Creating your first window Copy Chapter

Firstly, you will need to create a top-level window. Here, you configure things such as the name, position, geometry, and content of your window.

Let's look at an example window definition:

(defwindow example
           :monitor 0
           :geometry (geometry :x "0%"
                               :y "20px"
                               :width "90%"
                               :height "30px"
                               :anchor "top center")
           :stacking "fg"
           :reserve (struts :distance "40px" :side "top")
           :windowtype "dock"
           :wm-ignore false
  "example content")

Here, we are defining a window named example, which we then define a set of properties for. Additionally, we set the content of the window to be the text "example content".

You can now open your first window by running eww open example! Glorious!

`defwindow`-properties Copy Section

monitor-property

This field can be:

• the string ``, in which case eww tries to identify the primary display (which may fail, especially on wayland)
• an integer, declaring the monitor index
• the name of the monitor
• a string containing a JSON-array of monitor matchers, such as: '["", "HDMI-A-1", "PHL 345B1C", 0]'. Eww will try to find a match in order, allowing you to specify fallbacks.

geometry-properties

Depending on if you are using X11 or Wayland, some additional properties exist:

X11

Wayland

Your first widget Copy Chapter

While our bar is already looking great, it's a bit boring. Thus, let's add some actual content!

(defwidget greeter [?text name]
  (box :orientation "horizontal"
       :halign "center"
    text
    (button :onclick "notify-send 'Hello' 'Hello, ${name}'"
      "Greet")))

To show this, let's replace the text in our window definition with a call to this new widget:

(defwindow example
           ; ... values omitted
  (greeter :text "Say hello!"
           :name "Tim"))

There is a lot going on here, so let's step through this.

We are creating a widget named greeter. This widget takes two attributes, called text and name.
The declaration ?text specifies that the text-attribute is optional, and can thus be left out. In that case,
its value will be the empty string "".
The name attribute must be provided.

Now we declare the body of our widget. We make use of a box, which we set a couple attributes of.

We need this box, as a widget definition can only ever contain a single widget - otherwise,
eww would not know if it should align them vertically or horizontally, how it should space them, and so on.
Thus, we wrap multiple children in a box.
This box then contains a reference to the provided attribute text, as well as a button.
In that button's onclick attribute, we refer to the provided name using string-interpolation syntax: "${name}".
This allows us to easily refer to any variables within strings.
In fact, there is a lot more you can do within ${...} - more on that in the chapter about the expression language.

To then use our widget, we call it just like we would use any other built-in widget and provide the required attributes.

As you may have noticed, we are using a couple predefined widgets here. These are all listed and explained in the widgets chapter.

Rendering children in your widgets Copy Section

As your configuration grows, you might want to improve the structure of your config by factoring out functionality into basic reusable widgets.
Eww allows you to create custom wrapper widgets that can themselves take children, just like some of the built-in widgets like box or button can.
For this, use the children placeholder:

(defwidget labeled-container [name]
  (box :class "container"
    name
    (children)))

Now you can use this widget as expected:

(labeled-container :name "foo"
  (button :onclick "notify-send hey ho"
    "click me"))

You can also create more complex structure by referring to specific children with the nth-attribute:

(defwidget two-boxes []
  (box
    (box :class "first" (children :nth 0))
    (box :class "second" (children :nth 1))))

Adding dynamic content Copy Chapter

Now that you feel sufficiently greeted by your bar, you may realize that showing data like the time and date might be even more useful than having a button that greets you.

To implement dynamic content in your widgets, you make use of variables.

These user-defined variables are globally available from all of your widgets. Whenever the variable changes, the value in the widget will update!

There are four different types of variables: basic, polling, listening, and a set of builtin "magic" variables.

Basic variables (defvar)

(defvar foo "initial value")

This is the simplest type of variable.
Basic variables don't ever change automatically.
Instead, you explicitly update them by calling eww like so: eww update foo="new value".

This is useful if you have values that change very rarely, or may change as a result of some external script you wrote.
They may also be useful to have buttons within eww change what is shown within your widget, by setting attributes like onclick to run eww update.

Polling variables (defpoll)

(defvar time-visible false)   ; for :run-while property of below variable
                              ; when this turns true, the polling starts and
                              ; var gets updated with given interval

(defpoll time :interval "1s"
              :initial "initial-value"  ; optional, defaults to poll at startup
              :run-while time-visible   ; optional, defaults to 'true'
  `date +%H:%M:%S`)

A polling variable is a variable which runs a provided shell-script repeatedly, in a given interval.

This may be the most commonly used type of variable.
They are useful to access any quickly retrieved value repeatedly,
and thus are the perfect choice for showing your time, date, as well as other bits of information such as pending package updates, weather, and battery level.

You can also specify an initial-value. This should prevent eww from waiting for the result of a given command during startup, thus
making the startup time faster.

To externally update a polling variable, eww update can be used like with basic variables to assign a value.
You can also call eww poll to poll the variable outside of its usual interval, or even while it isn't running at all.

Listening variables (deflisten)

(deflisten foo :initial "whatever"
  `tail -F /tmp/some_file`)

Listening variables might be the most confusing of the bunch.
A listening variable runs a script once, and reads its output continously.
Whenever the script outputs a new line, the value will be updated to that new line.
In the example given above, the value of foo will start out as "whatever", and will change whenever a new line is appended to /tmp/some_file.

These are particularly useful when you want to apply changes instantaneously when an operation happens if you have a script
that can monitor some value on its own. Volume, brightness, workspaces that get added/removed at runtime,
monitoring currently focused desktop/tag, etc. are the most common usecases of this type of variable.
These are particularly efficient and should be preferred if possible.

For example, the command xprop -spy -root _NET_CURRENT_DESKTOP writes the currently focused desktop whenever it changes.
Another example usecase is monitoring the currently playing song with playerctl: playerctl --follow metadata --format {{title}}.

Built-in "magic" variables

In addition to defining your own variables, eww provides some values for you to use out of the box.
These include values such as your CPU and RAM usage.
These mostly contain their data as JSON, which you can then get using the json access syntax.
All available magic variables are listed here.

Dynamically generated widgets with `literal` Copy Chapter

In some cases, you want to not only change the text,
value, or color of a widget dynamically, but instead want to generate an entire widget structure dynamically.
This is necessary if you want to display lists of things (for example notifications)
where the amount is not necessarily known,
or if you want to change the widget structure in some other, more complex way.

For this, you can make use of one of eww's most powerful features: the literal widget.

(defvar variable_containing_yuck
  "(box (button 'foo') (button 'bar'))")

; Then, inside your widget, use:
(literal :content variable_containing_yuck)

Here, you specify the content of your literal by providing it a string (most likely stored in a variable) which contains a single yuck widget tree.
Eww then reads the provided value and renders the resulting widget. Whenever it changes, the widget will be rerendered.

Note that this is not all that efficient. Make sure to only use literal when necessary!

Using window arguments and IDs Copy Chapter

In some cases you may want to use the same window configuration for multiple widgets, e.g. for multiple windows. This is where arguments and ids come in.

Window ID Copy Section

Firstly let us start off with ids. An id can be specified in the open command
with --id, by default the id will be set to the name of the window
configuration. These ids allow you to spawn multiple of the same windows. So
for example you can do:

eww open my_bar --screen 0 --id primary
eww open my_bar --screen 1 --id secondary

When using open-many you can follow the structure below. Again if no id is
given, the id will default to the name of the window configuration.

eww open-many my_config:primary my_config:secondary

You may notice with this we didn't set screen, this is set through the
--arg system, please see below for more information.

Window Arguments Copy Section

However this may not be enough and you want to have slight changes for each of
these bars, e.g. having a different class for 1080p displays vs 4k or having
spawning the window in a different size or location. This is where the
arguments come in.

Please note these arguments are CONSTANT and so cannot be update after the
window has been opened.

Defining arguments in a window is the exact same as in a widget so you can
have:

(defwindow my_bar [arg1 ?arg2]
          :geometry (geometry
                       :x      "0%"
                       :y      "6px"
                       :width  "100%"
                       :height { arg1 == "small" ? "30px" : "40px" }
                       :anchor "top center")
          :stacking   "bg"
          :windowtype "dock"
          :reserve    (struts :distance "50px" :side "top")
    (my_widget :arg2 arg2))

Here we have two arguments, arg1 and arg2 (an optional parameter).

Once we have these parameters, when opening a new window, we must specify them
(unless they are optional, like arg2), but how? Well, we use the --arg
option when running the open command:

eww open my_bar --id primary --arg arg1=some_value --arg arg2=another_value

With the open-many it looks like this:

# Please note that `--arg` option must be given after all the windows names
eww open-many my_bar:primary --arg primary:arg1=some_value --arg primary:arg2=another_value

Using this method you can define screen, anchor, pos, size inside the
args for each window and it will act like giving --screen, --anchor etc. in
the open command.

So, now you know the basics, I shall introduce you to some of these "special"
parameters, which are set slightly differently. However these can all be
overridden by the --arg option.

• id - If id is included in the argument list, it will be set to the id
  specified by --id or will be set to the name of the config. This can be
  used when closing the current window through eww commands.
• screen - If screen is specified it will be set to the value given by
  --screen, so you can use this in other widgets to access screen specific
  information.

Further insight into args in `open-many` Copy Section

Now due to the system behind processing the open-many --arg option you
don't have to specify an id for each argument. If you do not, that argument
will be applied across all windows e.g.

eww open-many my_bar:primary my_bar:secondary --arg gui_size="small"

This will mean the config is the same throughout the bars.

Furthermore if you didn't specify an id for the window, you can still set args
specifically for that window - following the idea that the id will be set to
the window configuration if not given - by just using the name of the window
configuration e.g.

eww open-many my_primary_bar --arg my_primary_bar:screen=0

Generating a list of widgets from JSON using `for` Copy Chapter

If you want to display a list of values, you can use the for-Element to fill a container with a list of elements generated from a JSON-array.

(defvar my-json "[1, 2, 3]")

; Then, inside your widget, you can use
(box
  (for entry in my-json
    (button :onclick "notify-send 'click' 'button ${entry}'"
      entry)))

This can be useful in many situations, for example when generating a workspace list from a JSON representation of your workspaces.
In many cases, this can be used instead of literal, and should most likely be preferred in those cases.

To see how to declare and use more advanced data structures, check out the data structures example.

Splitting up your configuration Copy Chapter

As time passes, your configuration might grow larger and larger. Luckily, you can easily split up your configuration into multiple files!

There are two options to achieve this:

Using `include` Copy Section

(include "./path/to/your/file.yuck")

A single yuck file may import the contents of any other yuck file. For this, make use of the include directive.

Using a separate eww configuration directory Copy Section

If you want to separate different widgets even further, you can create a new eww config folder anywhere else.
Then, you can tell eww to use that configuration directory by passing every command the --config /path/to/your/config/dir flag.
Make sure to actually include this in all your eww calls, including eww kill, eww logs, etc.
This launches a separate instance of the eww daemon that has separate logs and state from your main eww configuration.

File: docs/src/eww.md Copy Chapter

Eww - Widgets for everyone!

Eww (ElKowar's Wacky Widgets, pronounced with sufficient amounts of disgust)
is a widget system made in Rust,
which lets you create your own widgets similarly to how you can in AwesomeWM.
The key difference: It is independent of your window manager!

Configured in yuck and themed using CSS, it is easy to customize and provides all the flexibility you need!

How to install Eww Copy Chapter

Prerequisites Copy Section

• rustc
• cargo

Rather than with your system package manager,
I strongly recommend installing it using rustup.

Additionally, eww requires some dynamic libraries to be available on your system.
The exact names of the packages that provide these may differ depending on your distribution.
The following list of package names should work for arch linux:

Packages

• gtk3 (libgdk-3, libgtk-3)
• gtk-layer-shell (only on Wayland)
• pango (libpango)
• gdk-pixbuf2 (libgdk_pixbuf-2)
• libdbusmenu-gtk3
• cairo (libcairo, libcairo-gobject)
• glib2 (libgio, libglib-2, libgobject-2)
• gcc-libs (libgcc)
• glibc

(Note that you will most likely need the -devel variants of your distro's packages to be able to compile eww.)

Building Copy Section

Once you have the prerequisites ready, you're ready to install and build eww.

First clone the repo:

git clone https://github.com/elkowar/eww

cd eww

Then build:

cargo build --release --no-default-features --features x11

NOTE:
When you're on Wayland, build with:

cargo build --release --no-default-features --features=wayland

Running eww Copy Section

Once you've built it you can now run it by entering:

cd target/release

Then make the Eww binary executable:

chmod +x ./eww

Then to run it, enter:

./eww daemon
./eww open <window_name>

File: docs/src/examples.md Copy Chapter

Example Configurations Copy Chapter

These configurations of eww are available in the examples/ directory of the repo.

An eww bar configuration:

A demo on how to declare and use data structures:

File: docs/src/expression_language.md Copy Chapter

Simple expression language

Yuck includes a small expression language that can be used to run several operations on your data.
This can be used to show different values depending on certain conditions,
do mathematic operations, and even access values within JSON-structures.

These expressions can be placed anywhere within your configuration inside { ... },
as well as within strings, inside string-interpolation blocks ("foo ${ ... } bar").

Example Copy Chapter

(box
  "Some math: ${12 + foo * 10}"
  (button :class {button_active ? "active" : "inactive"}
          :onclick "toggle_thing"
    {button_active ? "disable" : "enable"}))

Features Copy Chapter

Supported currently are the following features:

• simple mathematical operations (+, -, *, /, %)
• comparisons (==, !=, >, <, <=, >=)
• boolean operations (||, &&, !)
• regex match operator (=~)
  • Rust regex style, left hand is regex, right hand is string
  • ex: workspace.name =~ '^special:.+$'
• elvis operator (?:)
  • if the left side is "" or a JSON null, then returns the right side,
    otherwise evaluates to the left side.
• Safe Access operator (?.) or (?.[index])
  • if the left side is an empty string or a JSON null, then return null. Otherwise,
    attempt to index. Note that indexing an empty JSON string ('""') is an error.
  • This can still cause an error to occur if the left hand side exists but is
    not an object or an array.
    (Number or String).
• conditionals (condition ? 'value' : 'other value')
• numbers, strings, booleans and variable references (12, 'hi', true, some_variable)
• json access (object.field, array[12], object["field"])
  • for this, the object/array value needs to refer to a variable that contains a valid json string.
• some function calls:
  • round(number, decimal_digits): Round a number to the given amount of decimals
  • floor(number): Round a number down to the nearest integer
  • ceil(number): Round a number up to the nearest integer
  • sin(number), cos(number), tan(number), cot(number): Calculate the trigonometric value of a given number in radians
  • min(a, b), max(a, b): Get the smaller or bigger number out of two given numbers
  • powi(num, n), powf(num, n): Raise number num to power n. powi expects n to be of type i32
  • log(num, n): Calculate the base n logarithm of num. num, n and return type are f64
  • degtorad(number): Converts a number from degrees to radians
  • radtodeg(number): Converts a number from radians to degrees
  • replace(string, regex, replacement): Replace matches of a given regex in a string
  • search(string, regex): Search for a given regex in a string (returns array)
  • matches(string, regex): check if a given string matches a given regex (returns bool)
  • captures(string, regex): Get the captures of a given regex in a string (returns array)
  • strlength(value): Gets the length of the string
    • substring(string, start, length): Return a substring of given length starting at the given index
  • arraylength(value): Gets the length of the array
  • objectlength(value): Gets the amount of entries in the object
  • jq(value, jq_filter_string): run a jq style command on a json value. (Uses jaq internally).
  • jq(value, jq_filter_string, args): Emulate command line flags for jq, see the docs on invoking jq for details. Invalid flags are silently ignored.
    Currently supported flags:
    • "r": If the result is a string, it won't be formatted as a JSON string. The equivalent jq flag is --raw-output.
  • get_env(string): Gets the specified enviroment variable
  • formattime(unix_timestamp, format_str, timezone): Gets the time in a given format from UNIX timestamp.
    Check chrono's documentation for more
    information about format string and chrono-tz's documentation
    for available time zones.
  • formattime(unix_timestamp, format_str): Gets the time in a given format from UNIX timestamp.
    Same as other formattime, but does not accept timezone. Instead, it uses system's local timezone.
    Check chrono's documentation for more
    information about format string.
  • formatbytes(bytes, short, format_mode): Display bytes in a human-readable format.
    Arguments:
    • bytes: i64 of bytes, supports negative sizes.
    • short: set true for a compact version (default: false)
    • format_mode: set to either to "iec" (eg. 1.0 GiB) or "si" (eg. 1.2 GB) (default: "iec")

File: docs/src/magic-vars.md Copy Chapter

Magic variables

These are variables that are always there, without you having to import them.

The delay between all the updating variables except EWW_TIME is 2s, for EWW_TIME it is 1s.

File: docs/src/SUMMARY.md Copy Chapter

Summary

• Eww - Widgets for everyone!
• Configuration
• Eww expressions
• Theming with GTK
• Magic Variables
• Widgets
• Troubleshooting
• Examples

File: docs/src/troubleshooting.md Copy Chapter

Troubleshooting

Here you will find help if something doesn't work. If the issue isn't listed here, please open an issue on the GitHub repo.

Eww does not compile Copy Chapter

1. Make sure that you are compiling eww using a recent version of rust (run rustup update to be sure you have the latest version available)
2. Make sure you have all the necessary dependencies. If there are compile-errors, the compiler will tell you what you're missing.

Eww does not work on Wayland Copy Chapter

1. Make sure you compiled eww with the --no-default-features --features=wayland flags.
2. Make sure that you're not trying to use X11-specific features (these are (hopefully) explicitly specified as such in the documentation).

My configuration is not loaded correctly Copy Chapter

1. Make sure the eww.yuck and eww.(s)css files are in the correct places.
2. Sometimes, eww might fail to load your configuration as a result of a configuration error. Make sure your configuration is valid.

Something isn't styled correctly! Copy Chapter

Check the GTK-Debugger to get more insight into what styles GTK is applying to which elements.

General issues Copy Chapter

You should try the following things before opening an issue or doing more specialized troubleshooting:

• Kill the eww daemon by running eww kill and re-open your window with the --debug-flag to get additional log output.
• Now you can take a look at the logs by running eww logs.
• Use eww state to see the state of all variables.
• Use eww debug to see the structure of your widget and other information.
• Update to the latest eww version.
• Sometimes hot reloading doesn't work. In that case, you can make use of eww reload manually.

Remember, if your issue isn't listed here, open an issue on the GitHub repo.