GoogleContainerTools/skaffold · error

missing shell: %s

Error message

missing shell: %s

What it means

In `skaffold completion` (cmd/skaffold/app/cmd/completion.go:70), the cobra Args validator requires exactly one argument naming a shell. When zero or multiple arguments are given, this error is returned listing the valid shells (bash, fish, zsh) before cobra's OnlyValidArgs check runs.

Source

Thrown at cmd/skaffold/app/cmd/completion.go:70

func completion(cmd *cobra.Command, args []string) {
	switch args[0] {
	case "bash":
		rootCmd(cmd).GenBashCompletion(os.Stdout)
	case "fish":
		rootCmd(cmd).GenFishCompletion(os.Stdout, true)
	case "zsh":
		runCompletionZsh(cmd, os.Stdout)
	}
}

// NewCmdCompletion returns the cobra command that outputs shell completion code
func NewCmdCompletion() *cobra.Command {
	return &cobra.Command{
		Use: "completion SHELL",
		Args: func(cmd *cobra.Command, args []string) error {
			if len(args) != 1 {
				return fmt.Errorf("missing shell: %s", strings.Join(cmd.ValidArgs, ", "))
			}
			return cobra.OnlyValidArgs(cmd, args)
		},
		ValidArgs: []string{"bash", "fish", "zsh"},
		Short:     "Output shell completion for the given shell (bash, fish or zsh)",
		Long:      longDescription,
		Run:       completion,
	}
}

func runCompletionZsh(cmd *cobra.Command, out io.Writer) {
	rootCmd(cmd).GenZshCompletion(out)
	io.WriteString(out, zshCompdef)
}

func rootCmd(cmd *cobra.Command) *cobra.Command {
	parent := cmd
	for parent.HasParent() {

View on GitHub (pinned to a1189de023)

Solutions

1. Pass exactly one supported shell: `skaffold completion bash` (or fish, zsh)
2. Fix aliases/scripts that invoke completion without the shell argument
3. Source the output, e.g. `source <(skaffold completion bash)` in your shell rc
4. Check `skaffold completion --help` for the shells supported by your skaffold version

Example fix

// before
// skaffold completion        # missing shell
// after
// skaffold completion bash | source /dev/stdin   # or add to ~/.bashrc

// Validate the shell argument before invoking completion
validShells := map[string]bool{"bash": true, "fish": true, "zsh": true}
if !validShells[shell] {
    return fmt.Errorf("unsupported shell %q; use bash, fish or zsh", shell)
}

func isSupportedShell(s string) bool {
    switch s {
    case "bash", "fish", "zsh":
        return true
    }
    return false
}

if err := sh.Run("skaffold", "completion", shell); err != nil {
    if strings.Contains(err.Error(), "missing shell") {
        log.Fatalf("pass exactly one shell: skaffold completion <bash|fish|zsh>")
    }
    return err
}

When it happens

Trigger: Running `skaffold completion` with no argument, or with more than one argument (e.g. `skaffold completion bash zsh`); len(args) != 1 triggers the error message joined from cmd.ValidArgs.

Common situations: Older documentation or muscle memory from tools whose completion command takes no argument; shell alias dropping the argument; copy-pasting a command with an extra token; expecting powershell support which is not in ValidArgs.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• `apply` requires at least one manifest argument
• `exec` requires exactly one action to execute
• `config-dependencies add` requires exactly one file path arg
• `jobManifestPaths modify` requires exactly one manifest file
• `inspect namespaces list` requires exactly one manifest file

AI-assisted analysis of GoogleContainerTools/skaffold@a1189de023 (2026-09-05). Data as JSON: /api/errors/030a742c316a099b. Report an issue: GitHub.