caddyserver/caddy · error

reading stdin: %v

Error message

reading stdin: %v

What it means

Error "reading stdin: %v" thrown in caddyserver/caddy.

Source

Thrown at cmd/commandfuncs.go:701

}

func cmdFmt(fl Flags) (int, error) {
	configFile := fl.Arg(0)
	configFlag := fl.String("config")
	if (len(fl.Args()) > 1) || (configFlag != "" && configFile != "") {
		return caddy.ExitCodeFailedStartup, fmt.Errorf("fmt does not support multiple files %s %s", configFlag, strings.Join(fl.Args(), " "))
	}
	if configFile == "" && configFlag == "" {
		configFile = "Caddyfile"
	} else if configFile == "" {
		configFile = configFlag
	}
	// as a special case, read from stdin if the file name is "-"
	if configFile == "-" {
		input, err := io.ReadAll(os.Stdin)
		if err != nil {
			return caddy.ExitCodeFailedStartup,
				fmt.Errorf("reading stdin: %v", err)
		}
		fmt.Print(string(caddyfile.Format(input)))
		return caddy.ExitCodeSuccess, nil
	}

	input, err := os.ReadFile(configFile)
	if err != nil {
		return caddy.ExitCodeFailedStartup,
			fmt.Errorf("reading input file: %v", err)
	}

	output := caddyfile.Format(input)

	if fl.Bool("overwrite") {
		if err := os.WriteFile(configFile, output, 0o600); err != nil { //nolint:gosec // path traversal is not really a thing here, this is either "Caddyfile" or admin-controlled
			return caddy.ExitCodeFailedStartup, fmt.Errorf("overwriting formatted file: %v", err)
		}
		return caddy.ExitCodeSuccess, nil

View on GitHub (pinned to 50e54ee279)

Solutions

1. Ensure valid input is piped to stdin, or pass a file path instead of '-' to 'caddy fmt'.

When it happens

Trigger: Thrown at cmd/commandfuncs.go:701 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of caddyserver/caddy@50e54ee279 (2026-08-15). Data as JSON: /api/errors/d47b7fd61bdd4a81. Report an issue: GitHub.