The script for the ` `-variable exited unsuccessfully

Error message

The script for the `{}`-variable exited unsuccessfully

What it means

initial_value computes the first value of a script variable. For a `VarSource::Shell` (a shell command from `:command`), the command is run once synchronously; if it exits non-zero, eww wraps the failure warning in this error saying the script for the variable exited unsuccessfully.

Solutions

Run the :command string manually in a shell and fix whatever makes it exit non-zero
Make the script exit 0 even on failure (e.g. append `|| echo 'fallback'` or `2>/dev/null || true`)
Install missing dependencies the script relies on

Example fix

; before
(defpoll cpu :interval "1s" "mpstat 1 1 | awk '/Average/{print $3}'")  ; mpstat not installed

; after
(defpoll cpu :interval "1s" "command -v mpstat >/dev/null && mpstat 1 1 | awk '/Average/{print $3}' || echo 0")

Defensive patterns

Strategy: try-catch

Validate before calling

// shell: verify the command succeeds before configuring it
mycommand || echo "fix: exits $?, would break initial value"

Try / catch

match script_var::initial_value(&var) {
    Ok(v) => /* use v */,
    Err(e) => log::warn!("using default for {}: {e:#}", var.name()),
}

Prevention

Test every :command manually first
Always end poll scripts with a guaranteed exit 0 fallback
Install dependencies before deploying the config

When it happens

Trigger: Defining a polled/initial script var whose `:command` shell string fails on first evaluation — command not found, non-zero exit, bad syntax — when the initial value is computed.

Common situations: Command depends on a tool not installed; script fails on a fresh machine before dependencies exist; quoting errors in the yuck command string; command exits non-zero under eww's environment.

Related errors

AI-assisted analysis of elkowar/eww@48f5aa8b37 (2026-09-08). Data as JSON: /api/errors/fb5563a397aad6eb. Report an issue: GitHub.

Appendix: source

Thrown at crates/eww/src/config/script_var.rs:31

pub fn create_script_var_failed_warn(span: Span, var_name: &VarName, error_output: &str) -> DiagError {
    DiagError(gen_diagnostic! {
        kind = Severity::Warning,
        msg = format!("The script for the `{}`-variable exited unsuccessfully", var_name),
        label = span => "Defined here",
        note = error_output,
    })
}

pub fn initial_value(var: &ScriptVarDefinition) -> Result<DynVal> {
    match var {
        ScriptVarDefinition::Poll(x) => match &x.initial_value {
            Some(value) => Ok(value.clone()),
            None => match &x.command {
                VarSource::Function(f) => f()
                    .map_err(|err| anyhow!(err))
                    .with_context(|| format!("Failed to compute initial value for {}", &var.name())),
                VarSource::Shell(span, command) => {
                    run_command(command).map_err(|e| anyhow!(create_script_var_failed_warn(*span, var.name(), &e.to_string())))
                }
            },
        },

        ScriptVarDefinition::Listen(var) => Ok(var.initial_value.clone()),
    }
}

/// Run a command and get the output
pub fn run_command(cmd: &str) -> Result<DynVal> {
    log::debug!("Running command: {}", cmd);
    let command = Command::new("/bin/sh").arg("-c").arg(cmd).output()?;
    if !command.status.success() {
        bail!("Failed with output:\n{}", String::from_utf8(command.stderr)?);
    }
    let output = String::from_utf8(command.stdout)?;
    let output = output.trim_matches('\n');
    Ok(DynVal::from(output))

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