charmbracelet/crush · warning

empty command

Error message

empty command

What it means

ExecShell in internal/ui/util splits the command string with shell.Fields; if splitting succeeds but yields zero fields (i.e. the command string is empty or only whitespace/comments), it refuses to exec and reports this error rather than calling exec with no binary.

Source

Thrown at internal/ui/util/util.go:91

	ClearStatusMsg struct{}
)

// IsEmpty checks if the [InfoMsg] is empty.
func (m InfoMsg) IsEmpty() bool {
	var zero InfoMsg
	return m == zero
}

// ExecShell parses a shell command string and executes it with exec.Command.
// Uses shell.Fields for proper handling of shell syntax like quotes and
// arguments while preserving TTY handling for terminal editors.
func ExecShell(ctx context.Context, cmdStr string, callback tea.ExecCallback) tea.Cmd {
	fields, err := shell.Fields(cmdStr, nil)
	if err != nil {
		return ReportError(err)
	}
	if len(fields) == 0 {
		return ReportError(errors.New("empty command"))
	}

	cmd := exec.CommandContext(ctx, fields[0], fields[1:]...)
	return tea.ExecProcess(cmd, callback)
}

View on GitHub (pinned to 7944b8e522)

Solutions

1. Guard the caller: skip ExecShell when the trimmed command string is empty
2. Show a validation message to the user instead of dispatching an empty command
3. Trim and non-empty check the input at the UI boundary

Example fix

// before
util.ExecShell(ctx, cmdStr, callback)
// after
if strings.TrimSpace(cmdStr) != "" {
	cmds = append(cmds, util.ExecShell(ctx, cmdStr, callback))
}

if strings.TrimSpace(cmdStr) == "" {
	return
}

func hasCommand(s string) bool { return strings.TrimSpace(s) != "" }

if err, ok := <-errCh; ok && err.Error() == "empty command" { /* skip */ }

When it happens

Trigger: Calling ExecShell with cmdStr == "" or a whitespace-only string; also when shell.Fields reduces the input to nothing (e.g. a string that is only a shell comment).

Common situations: TUI commands executing a user/editor-supplied command buffer that is empty; variables expanding to empty before the call; copying a command but pasting only whitespace.

Related errors

• Crush crashed. If metrics are enabled, we were notified abou
• configuration not found
• agent configuration not found
• session ID is required for executing shell command
• error starting background shell: %w

AI-assisted analysis of charmbracelet/crush@7944b8e522 (2026-08-29). Data as JSON: /api/errors/af545f47ee908484. Report an issue: GitHub.