lima-vm/lima · error

unknown format: %#q

Error message

unknown format: %#q

What it means

The requested output format for formatting an SSH command/config string is not recognized (expected values like `cmd` or `args`).

Source

Thrown at pkg/sshutil/format.go:102

		for _, o := range opts {
			args = append(args, "-o", quoteOption(o))
		}
		fmt.Fprintln(w, strings.Join(args, " ")) // no need to use shellescape.QuoteCommand
	case FormatOptions:
		for _, o := range opts {
			fmt.Fprintln(w, o)
		}
	case FormatConfig:
		fmt.Fprintf(w, "Host %s\n", fakeHostname)
		for _, o := range opts {
			kv := strings.SplitN(o, "=", 2)
			if len(kv) != 2 {
				return fmt.Errorf("unexpected option %#q", o)
			}
			fmt.Fprintf(w, "  %s %s\n", kv[0], kv[1])
		}
	default:
		return fmt.Errorf("unknown format: %#q", format)
	}
	return nil
}

View on GitHub (pinned to dd909d0973)

Solutions

1. Use the exported constants sshutil.FormatCmd or sshutil.FormatConfig instead of raw strings.
2. Validate any externally sourced format value against the supported set before calling Format.
3. Check for an uninitialized/zero-valued FormatT variable at the call site.

Example fix

// before
var format sshutil.FormatT
sshutil.Format(w, sshPath, instName, format, opts) // "unknown format"
// after
format := sshutil.FormatConfig
sshutil.Format(w, sshPath, instName, format, opts)

if format != sshutil.FormatCmd && format != sshutil.FormatConfig {
    return fmt.Errorf("unsupported format %q", format)
}

func validFormat(f sshutil.FormatT) bool { return f == sshutil.FormatCmd || f == sshutil.FormatConfig }

if err := sshutil.Format(w, sshPath, instName, format, opts); err != nil {
    if strings.Contains(err.Error(), "unknown format") {
        // fall back to sshutil.FormatConfig
    }
}

When it happens

Trigger: Passing a FormatT value that is neither "cmd" nor "config" (zero-value struct/empty string, wrong constant, or a value produced by unvalidated user input) to sshutil.Format.

Common situations: Constructing FormatT from CLI flags or config files without validation; refactoring that renames the constants; uninitialized variables defaulting to the zero value.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• failed to create the synced workdir in guest instance: %w
• failed to rsync to the guest %w
• failed to sync back the changes from guest instance to host:
• failed to sync back the changes from guest instance to host
• no SSH key was found, run `ssh-keygen`

AI-assisted analysis of lima-vm/lima@dd909d0973 (2026-09-01). Data as JSON: /api/errors/cf4203e7cb5ec201. Report an issue: GitHub.