# Rigerc Claude Bubbletea Skills Cobra > Cobra CLI Framework - Skill: `tomevault-io/rigerc-claude-bubbletea-skills-cobra` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/rigerc-claude-bubbletea-skills-cobra` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/rigerc-claude-bubbletea-skills-cobra/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/rigerc-claude-bubbletea-skills-cobra --- # Cobra CLI Framework Cobra is a library for creating powerful modern CLI applications in Go, used by Kubernetes, Hugo, GitHub CLI, and many more. ## Core Concepts **Commands** represent actions, **Args** are things, **Flags** are modifiers. Follow the pattern: `APPNAME COMMAND ARG --FLAG`. ## Project Structure ``` appName/ cmd/ root.go subcommand.go main.go ``` ## Creating Commands ### Root Command ```go package cmd import ( "fmt" "os" "github.com/spf13/cobra" ) var rootCmd = &cobra.Command{ Use: "myapp", Short: "Brief description", Long: `Detailed description...`, Run: func(cmd *cobra.Command, args []string) { // Action here }, } func Execute() { if err := rootCmd.Execute(); err != nil { fmt.Fprintln(os.Stderr, err) os.Exit(1) } } ``` ### Subcommands ```go var versionCmd = &cobra.Command{ Use: "version", Short: "Print version", Run: func(cmd *cobra.Command, args []string) { fmt.Println("v1.0.0") }, } func init() { rootCmd.AddCommand(versionCmd) } ``` ### Error Handling with RunE ```go var cmd = &cobra.Command{ Use: "delete [name]", RunE: func(cmd *cobra.Command, args []string) error { if len(args) == 0 { return fmt.Errorf("name required") } return deleteResource(args[0]) }, } ``` ## Flags ### Persistent Flags (cascade to children) ```go var verbose bool func init() { rootCmd.PersistentFlags().BoolVarP(&verbose, "verbose", "v", false, "verbose output") } ``` ### Local Flags (command-specific) ```go var source string func init() { cmd.Flags().StringVarP(&source, "source", "s", "", "source directory") } ``` ### Required Flags ```go func init() { rootCmd.Flags().StringVarP(®ion, "region", "r", "", "AWS region") rootCmd.MarkFlagRequired("region") } ``` ### Flag Groups ```go func init() { rootCmd.Flags().StringVarP(&user, "username", "u", "", "Username") rootCmd.Flags().StringVarP(&pass, "password", "p", "", "Password") rootCmd.MarkFlagsRequiredTogether("username", "password") rootCmd.MarkFlagsMutuallyExclusive("json", "yaml") } ``` ### Count/Array Flags ```go var verbose int var files []string func init() { rootCmd.PersistentFlags().CountVarP(&verbose, "verbose", "v", "verbosity (-v, -vv, -vvv)") rootCmd.Flags().StringArrayVarP(&files, "file", "f", []string{}, "input files") } ``` ## Argument Validation ```go var cmd = &cobra.Command{ Use: "create [name]", Args: cobra.ExactArgs(1), Run: func(cmd *cobra.Command, args []string) { ... }, } ``` Built-in validators: - `NoArgs` - no positional args allowed - `ArbitraryArgs` - any number (default) - `MinimumNArgs(int)` - at least N args - `MaximumNArgs(int)` - at most N args - `ExactArgs(int)` - exactly N args - `RangeArgs(min, max)` - between min and max - `OnlyValidArgs` - only values in ValidArgs Combined validation: ```go Args: cobra.MatchAll(cobra.ExactArgs(2), cobra.OnlyValidArgs), ``` ## PreRun/PostRun Hooks Execution order: `PersistentPreRun` -> `PreRun` -> `Run` -> `PostRun` -> `PersistentPostRun` ```go var rootCmd = &cobra.Command{ Use: "myapp", PersistentPreRun: func(cmd *cobra.Command, args []string) { // Runs before any child command }, PreRun: func(cmd *cobra.Command, args []string) { // Runs before this command's Run }, Run: func(cmd *cobra.Command, args []string) { // Main logic }, PostRun: func(cmd *cobra.Command, args []string) { // Runs after Run }, PersistentPostRun: func(cmd *cobra.Command, args []string) { // Runs after any child command }, } ``` ## Shell Completions ### Static Completions ```go var cmd = &cobra.Command{ Use: "get [resource]", ValidArgs: []string{"pod", "service", "deployment"}, Run: func(cmd *cobra.Command, args []string) { ... }, } ``` ### Dynamic Completions ```go var cmd = &cobra.Command{ Use: "status [release]", ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]cobra.Completion, cobra.ShellCompDirective) { return getReleases(toComplete), cobra.ShellCompDirectiveNoFileComp }, Run: func(cmd *cobra.Command, args []string) { ... }, } ``` ### Flag Completions ```go cmd.RegisterFlagCompletionFunc("output", func(cmd *cobra.Command, args []string, toComplete string) ([]cobra.Completion, cobra.ShellCompDirective) { return []cobra.Completion{"json", "yaml", "table"}, cobra.ShellCompDirectiveNoFileComp }) ``` ### ShellCompDirective Values - `ShellCompDirectiveDefault` - default behavior - `ShellCompDirectiveNoSpace` - no space after completion - `ShellCompDirectiveNoFileComp` - no file completion - `ShellCompDirectiveFilterFileExt` - filter by file extension - `ShellCompDirectiveFilterDirs` - directory names only ## Help Customization ```go cmd.SetHelpCommand(customHelpCmd) cmd.SetHelpFunc(func(cmd *cobra.Command, args []string) { ... }) cmd.SetHelpTemplate(customTemplate) cmd.SetUsageFunc(func(cmd *cobra.Command) error { ... }) cmd.SetUsageTemplate(customTemplate) ``` ## Version Flag ```go var rootCmd = &cobra.Command{ Use: "myapp", Version: "1.0.0", } ``` ## Command Groups ```go func init() { rootCmd.AddGroup( &cobra.Group{ID: "management", Title: "Management Commands:"}, &cobra.Group{ID: "query", Title: "Query Commands:"}, ) listCmd.GroupID = "query" createCmd.GroupID = "management" rootCmd.AddCommand(listCmd, createCmd) } ``` ## Plugin Support (kubectl-style) ```go rootCmd := &cobra.Command{ Use: "kubectl-myplugin", Annotations: map[string]string{ cobra.CommandDisplayNameAnnotation: "kubectl myplugin", }, } ``` ## Common Patterns ### Traverse Children Flags ```go rootCmd := &cobra.Command{ Use: "myapp", TraverseChildren: true, // Parse parent flags before child command } ``` ### Silence Errors/Usage ```go cmd.SilenceErrors = true // Don't print error prefix cmd.SilenceUsage = true // Don't print usage on error ``` ### Hidden Commands ```go cmd.Hidden = true ``` ### Deprecated Commands ```go cmd.Deprecated = "use 'newcmd' instead" ``` ## Examples Index | File | Description | |------|-------------| | [references/_examples/basic_app.go](references/_examples/basic_app.go) | Minimal CLI application | | [references/_examples/subcommands.go](references/_examples/subcommands.go) | Nested subcommands | | [references/_examples/flags.go](references/_examples/flags.go) | Flag patterns | | [references/_examples/hooks.go](references/_examples/hooks.go) | PreRun/PostRun hooks | | [references/_examples/completions.go](references/_examples/completions.go) | Shell completions | ## Integration with Viper ```go import "github.com/spf13/viper" func init() { rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file") rootCmd.PersistentFlags().StringP("author", "a", "", "author name") viper.BindPFlag("author", rootCmd.PersistentFlags().Lookup("author")) } ``` ## Further Reading - [User Guide](references/user_guide.md) - Complete user guide documentation - [Shell Completions](references/completions.md) - Detailed completion documentation - [Active Help](references/active_help.md) - Context-sensitive help messages --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/rigerc) — claim your Tome and manage your conversions.