cli === [![Build Status](https://travis-ci.org/urfave/cli.svg?branch=master)](https://travis-ci.org/urfave/cli) [![Windows Build Status](https://ci.appveyor.com/api/projects/status/rtgk5xufi932pb2v?svg=true)](https://ci.appveyor.com/project/urfave/cli) [![GoDoc](https://godoc.org/github.com/urfave/cli?status.svg)](https://godoc.org/github.com/urfave/cli) [![codebeat](https://codebeat.co/badges/0a8f30aa-f975-404b-b878-5fab3ae1cc5f)](https://codebeat.co/projects/github-com-urfave-cli) [![Go Report Card](https://goreportcard.com/badge/urfave/cli)](https://goreportcard.com/report/urfave/cli) [![top level coverage](https://gocover.io/_badge/github.com/urfave/cli?0 "top level coverage")](http://gocover.io/github.com/urfave/cli) / [![altsrc coverage](https://gocover.io/_badge/github.com/urfave/cli/altsrc?0 "altsrc coverage")](http://gocover.io/github.com/urfave/cli/altsrc) **Notice:** This is the library formerly known as `github.com/codegangsta/cli` -- Github will automatically redirect requests to this repository, but we recommend updating your references for clarity. cli is a simple, fast, and fun package for building command line apps in Go. The goal is to enable developers to write fast and distributable command line applications in an expressive way. - [Overview](#overview) - [Installation](#installation) * [Supported platforms](#supported-platforms) * [Using the `v2` branch](#using-the-v2-branch) * [Pinning to the `v1` releases](#pinning-to-the-v1-releases) - [Getting Started](#getting-started) - [Examples](#examples) * [Arguments](#arguments) * [Flags](#flags) + [Placeholder Values](#placeholder-values) + [Alternate Names](#alternate-names) + [Ordering](#ordering) + [Values from the Environment](#values-from-the-environment) + [Values from files](#values-from-files) + [Values from alternate input sources (YAML, TOML, and others)](#values-from-alternate-input-sources-yaml-toml-and-others) + [Precedence](#precedence) * [Subcommands](#subcommands) * [Subcommands categories](#subcommands-categories) * [Exit code](#exit-code) * [Bash Completion](#bash-completion) + [Enabling](#enabling) + [Distribution](#distribution) + [Customization](#customization) * [Generated Help Text](#generated-help-text) + [Customization](#customization-1) * [Version Flag](#version-flag) + [Customization](#customization-2) + [Full API Example](#full-api-example) * [Combining short Bool options](#combining-short-bool-options) - [Contribution Guidelines](#contribution-guidelines) ## Overview Command line apps are usually so tiny that there is absolutely no reason why your code should *not* be self-documenting. Things like generating help text and parsing command flags/options should not hinder productivity when writing a command line app. **This is where cli comes into play.** cli makes command line programming fun, organized, and expressive! ## Installation Make sure you have a working Go environment. Go version 1.2+ is supported. [See the install instructions for Go](http://golang.org/doc/install.html). To install cli, simply run: ``` $ go get github.com/urfave/cli ``` Make sure your `PATH` includes the `$GOPATH/bin` directory so your commands can be easily used: ``` export PATH=$PATH:$GOPATH/bin ``` ### Supported platforms cli is tested against multiple versions of Go on Linux, and against the latest released version of Go on OS X and Windows. For full details, see [`./.travis.yml`](./.travis.yml) and [`./appveyor.yml`](./appveyor.yml). ### Using the `v2` branch **Warning**: The `v2` branch is currently unreleased and considered unstable. There is currently a long-lived branch named `v2` that is intended to land as the new `master` branch once development there has settled down. The current `master` branch (mirrored as `v1`) is being manually merged into `v2` on an irregular human-based schedule, but generally if one wants to "upgrade" to `v2` *now* and accept the volatility (read: "awesomeness") that comes along with that, please use whatever version pinning of your preference, such as via `gopkg.in`: ``` $ go get gopkg.in/urfave/cli.v2 ``` ``` go ... import ( "gopkg.in/urfave/cli.v2" // imports as package "cli" ) ... ``` ### Pinning to the `v1` releases Similarly to the section above describing use of the `v2` branch, if one wants to avoid any unexpected compatibility pains once `v2` becomes `master`, then pinning to `v1` is an acceptable option, e.g.: ``` $ go get gopkg.in/urfave/cli.v1 ``` ``` go ... import ( "gopkg.in/urfave/cli.v1" // imports as package "cli" ) ... ``` This will pull the latest tagged `v1` release (e.g. `v1.18.1` at the time of writing). ## Getting Started One of the philosophies behind cli is that an API should be playful and full of discovery. So a cli app can be as little as one line of code in `main()`. ``` go package main import ( "os" "github.com/urfave/cli" ) func main() { cli.NewApp().Run(os.Args) } ``` This app will run and show help text, but is not very useful. Let's give an action to execute and some help documentation: ``` go package main import ( "fmt" "os" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Name = "boom" app.Usage = "make an explosive entrance" app.Action = func(c *cli.Context) error { fmt.Println("boom! I say!") return nil } app.Run(os.Args) } ``` Running this already gives you a ton of functionality, plus support for things like subcommands and flags, which are covered below. ## Examples Being a programmer can be a lonely job. Thankfully by the power of automation that is not the case! Let's create a greeter app to fend off our demons of loneliness! Start by creating a directory named `greet`, and within it, add a file, `greet.go` with the following code in it: ``` go package main import ( "fmt" "os" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Name = "greet" app.Usage = "fight the loneliness!" app.Action = func(c *cli.Context) error { fmt.Println("Hello friend!") return nil } app.Run(os.Args) } ``` Install our command to the `$GOPATH/bin` directory: ``` $ go install ``` Finally run our new command: ``` $ greet Hello friend! ``` cli also generates neat help text: ``` $ greet help NAME: greet - fight the loneliness! USAGE: greet [global options] command [command options] [arguments...] VERSION: 0.0.0 COMMANDS: help, h Shows a list of commands or help for one command GLOBAL OPTIONS --version Shows version information ``` ### Arguments You can lookup arguments by calling the `Args` function on `cli.Context`, e.g.: ``` go package main import ( "fmt" "os" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Action = func(c *cli.Context) error { fmt.Printf("Hello %q", c.Args().Get(0)) return nil } app.Run(os.Args) } ``` ### Flags Setting and querying flags is simple. ``` go package main import ( "fmt" "os" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Flags = []cli.Flag { cli.StringFlag{ Name: "lang", Value: "english", Usage: "language for the greeting", }, } app.Action = func(c *cli.Context) error { name := "Nefertiti" if c.NArg() > 0 { name = c.Args().Get(0) } if c.String("lang") == "spanish" { fmt.Println("Hola", name) } else { fmt.Println("Hello", name) } return nil } app.Run(os.Args) } ``` You can also set a destination variable for a flag, to which the content will be scanned. ``` go package main import ( "os" "fmt" "github.com/urfave/cli" ) func main() { var language string app := cli.NewApp() app.Flags = []cli.Flag { cli.StringFlag{ Name: "lang", Value: "english", Usage: "language for the greeting", Destination: &language, }, } app.Action = func(c *cli.Context) error { name := "someone" if c.NArg() > 0 { name = c.Args()[0] } if language == "spanish" { fmt.Println("Hola", name) } else { fmt.Println("Hello", name) } return nil } app.Run(os.Args) } ``` See full list of flags at http://godoc.org/github.com/urfave/cli #### Placeholder Values Sometimes it's useful to specify a flag's value within the usage string itself. Such placeholders are indicated with back quotes. For example this: ```go package main import ( "os" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Flags = []cli.Flag{ cli.StringFlag{ Name: "config, c", Usage: "Load configuration from `FILE`", }, } app.Run(os.Args) } ``` Will result in help output like: ``` --config FILE, -c FILE Load configuration from FILE ``` Note that only the first placeholder is used. Subsequent back-quoted words will be left as-is. #### Alternate Names You can set alternate (or short) names for flags by providing a comma-delimited list for the `Name`. e.g. ``` go package main import ( "os" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Flags = []cli.Flag { cli.StringFlag{ Name: "lang, l", Value: "english", Usage: "language for the greeting", }, } app.Run(os.Args) } ``` That flag can then be set with `--lang spanish` or `-l spanish`. Note that giving two different forms of the same flag in the same command invocation is an error. #### Ordering Flags for the application and commands are shown in the order they are defined. However, it's possible to sort them from outside this library by using `FlagsByName` or `CommandsByName` with `sort`. For example this: ``` go package main import ( "os" "sort" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Flags = []cli.Flag { cli.StringFlag{ Name: "lang, l", Value: "english", Usage: "Language for the greeting", }, cli.StringFlag{ Name: "config, c", Usage: "Load configuration from `FILE`", }, } app.Commands = []cli.Command{ { Name: "complete", Aliases: []string{"c"}, Usage: "complete a task on the list", Action: func(c *cli.Context) error { return nil }, }, { Name: "add", Aliases: []string{"a"}, Usage: "add a task to the list", Action: func(c *cli.Context) error { return nil }, }, } sort.Sort(cli.FlagsByName(app.Flags)) sort.Sort(cli.CommandsByName(app.Commands)) app.Run(os.Args) } ``` Will result in help output like: ``` --config FILE, -c FILE Load configuration from FILE --lang value, -l value Language for the greeting (default: "english") ``` #### Values from the Environment You can also have the default value set from the environment via `EnvVar`. e.g. ``` go package main import ( "os" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Flags = []cli.Flag { cli.StringFlag{ Name: "lang, l", Value: "english", Usage: "language for the greeting", EnvVar: "APP_LANG", }, } app.Run(os.Args) } ``` The `EnvVar` may also be given as a comma-delimited "cascade", where the first environment variable that resolves is used as the default. ``` go package main import ( "os" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Flags = []cli.Flag { cli.StringFlag{ Name: "lang, l", Value: "english", Usage: "language for the greeting", EnvVar: "LEGACY_COMPAT_LANG,APP_LANG,LANG", }, } app.Run(os.Args) } ``` #### Values from files You can also have the default value set from file via `FilePath`. e.g. ``` go package main import ( "os" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Flags = []cli.Flag { cli.StringFlag{ Name: "password, p", Usage: "password for the mysql database", FilePath: "/etc/mysql/password", }, } app.Run(os.Args) } ``` Note that default values set from file (e.g. `FilePath`) take precedence over default values set from the enviornment (e.g. `EnvVar`). #### Values from alternate input sources (YAML, TOML, and others) There is a separate package altsrc that adds support for getting flag values from other file input sources. Currently supported input source formats: * YAML * TOML In order to get values for a flag from an alternate input source the following code would be added to wrap an existing cli.Flag like below: ``` go altsrc.NewIntFlag(cli.IntFlag{Name: "test"}) ``` Initialization must also occur for these flags. Below is an example initializing getting data from a yaml file below. ``` go command.Before = altsrc.InitInputSourceWithContext(command.Flags, NewYamlSourceFromFlagFunc("load")) ``` The code above will use the "load" string as a flag name to get the file name of a yaml file from the cli.Context. It will then use that file name to initialize the yaml input source for any flags that are defined on that command. As a note the "load" flag used would also have to be defined on the command flags in order for this code snipped to work. Currently only the aboved specified formats are supported but developers can add support for other input sources by implementing the altsrc.InputSourceContext for their given sources. Here is a more complete sample of a command using YAML support: ``` go package notmain import ( "fmt" "os" "github.com/urfave/cli" "github.com/urfave/cli/altsrc" ) func main() { app := cli.NewApp() flags := []cli.Flag{ altsrc.NewIntFlag(cli.IntFlag{Name: "test"}), cli.StringFlag{Name: "load"}, } app.Action = func(c *cli.Context) error { fmt.Println("yaml ist rad") return nil } app.Before = altsrc.InitInputSourceWithContext(flags, altsrc.NewYamlSourceFromFlagFunc("load")) app.Flags = flags app.Run(os.Args) } ``` #### Precedence The precedence for flag value sources is as follows (highest to lowest): 0. Command line flag value from user 0. Environment variable (if specified) 0. Configuration file (if specified) 0. Default defined on the flag ### Subcommands Subcommands can be defined for a more git-like command line app. ```go package main import ( "fmt" "os" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Commands = []cli.Command{ { Name: "add", Aliases: []string{"a"}, Usage: "add a task to the list", Action: func(c *cli.Context) error { fmt.Println("added task: ", c.Args().First()) return nil }, }, { Name: "complete", Aliases: []string{"c"}, Usage: "complete a task on the list", Action: func(c *cli.Context) error { fmt.Println("completed task: ", c.Args().First()) return nil }, }, { Name: "template", Aliases: []string{"t"}, Usage: "options for task templates", Subcommands: []cli.Command{ { Name: "add", Usage: "add a new template", Action: func(c *cli.Context) error { fmt.Println("new task template: ", c.Args().First()) return nil }, }, { Name: "remove", Usage: "remove an existing template", Action: func(c *cli.Context) error { fmt.Println("removed task template: ", c.Args().First()) return nil }, }, }, }, } app.Run(os.Args) } ``` ### Subcommands categories For additional organization in apps that have many subcommands, you can associate a category for each command to group them together in the help output. E.g. ```go package main import ( "os" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Commands = []cli.Command{ { Name: "noop", }, { Name: "add", Category: "Template actions", }, { Name: "remove", Category: "Template actions", }, } app.Run(os.Args) } ``` Will include: ``` COMMANDS: noop Template actions: add remove ``` ### Exit code Calling `App.Run` will not automatically call `os.Exit`, which means that by default the exit code will "fall through" to being `0`. An explicit exit code may be set by returning a non-nil error that fulfills `cli.ExitCoder`, *or* a `cli.MultiError` that includes an error that fulfills `cli.ExitCoder`, e.g.: ``` go package main import ( "os" "github.com/urfave/cli" ) func main() { app := cli.NewApp() app.Flags = []cli.Flag{ cli.BoolTFlag{ Name: "ginger-crouton", Usage: "is it in the soup?", }, } app.Action = func(ctx *cli.Context) error { if !ctx.Bool("ginger-crouton") { return cli.NewExitError("it is not in the soup", 86) } return nil } app.Run(os.Args) } ``` ### Bash Completion You can enable completion commands by setting the `EnableBashCompletion` flag on the `App` object. By default, this setting will only auto-complete to show an app's subcommands, but you can write your own completion methods for the App or its subcommands. ``` go package main import ( "fmt" "os" "github.com/urfave/cli" ) func main() { tasks := []string{"cook", "clean", "laundry", "eat", "sleep", "code"} app := cli.NewApp() app.EnableBashCompletion = true app.Commands = []cli.Command{ { Name: "complete", Aliases: []string{"c"}, Usage: "complete a task on the list", Action: func(c *cli.Context) error { fmt.Println("completed task: ", c.Args().First()) return nil }, BashComplete: func(c *cli.Context) { // This will complete if no args are passed if c.NArg() > 0 { return } for _, t := range tasks { fmt.Println(t) } }, }, } app.Run(os.Args) } ``` #### Enabling Source the `autocomplete/bash_autocomplete` file in your `.bashrc` file while setting the `PROG` variable to the name of your program: `PROG=myprogram source /.../cli/autocomplete/bash_autocomplete` #### Distribution Copy `autocomplete/bash_autocomplete` into `/etc/bash_completion.d/` and rename it to the name of the program you wish to add autocomplete support for (or automatically install it there if you are distributing a package). Don't forget to source the file to make it active in the current shell. ``` sudo cp src/bash_autocomplete /etc/bash_completion.d/ source /etc/bash_completion.d/ ``` Alternatively, you can just document that users should source the generic `autocomplete/bash_autocomplete` in their bash configuration with `$PROG` set to the name of their program (as above). #### Customization The default bash completion flag (`--generate-bash-completion`) is defined as `cli.BashCompletionFlag`, and may be redefined if desired, e.g.: ``` go package main import ( "os" "github.com/urfave/cli" ) func main() { cli.BashCompletionFlag = cli.BoolFlag{ Name: "compgen", Hidden: true, } app := cli.NewApp() app.EnableBashCompletion = true app.Commands = []cli.Command{ { Name: "wat", }, } app.Run(os.Args) } ``` ### Generated Help Text The default help flag (`-h/--help`) is defined as `cli.HelpFlag` and is checked by the cli internals in order to print generated help text for the app, command, or subcommand, and break execution. #### Customization All of the help text generation may be customized, and at multiple levels. The templates are exposed as variables `AppHelpTemplate`, `CommandHelpTemplate`, and `SubcommandHelpTemplate` which may be reassigned or augmented, and full override is possible by assigning a compatible func to the `cli.HelpPrinter` variable, e.g.: ``` go package main import ( "fmt" "io" "os" "github.com/urfave/cli" ) func main() { // EXAMPLE: Append to an existing template cli.AppHelpTemplate = fmt.Sprintf(`%s WEBSITE: http://awesometown.example.com SUPPORT: support@awesometown.example.com `, cli.AppHelpTemplate) // EXAMPLE: Override a template cli.AppHelpTemplate = `NAME: {{.Name}} - {{.Usage}} USAGE: {{.HelpName}} {{if .VisibleFlags}}[global options]{{end}}{{if .Commands}} command [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}} {{if len .Authors}} AUTHOR: {{range .Authors}}{{ . }}{{end}} {{end}}{{if .Commands}} COMMANDS: {{range .Commands}}{{if not .HideHelp}} {{join .Names ", "}}{{ "\t"}}{{.Usage}}{{ "\n" }}{{end}}{{end}}{{end}}{{if .VisibleFlags}} GLOBAL OPTIONS: {{range .VisibleFlags}}{{.}} {{end}}{{end}}{{if .Copyright }} COPYRIGHT: {{.Copyright}} {{end}}{{if .Version}} VERSION: {{.Version}} {{end}} ` // EXAMPLE: Replace the `HelpPrinter` func cli.HelpPrinter = func(w io.Writer, templ string, data interface{}) { fmt.Println("Ha HA. I pwnd the help!!1") } cli.NewApp().Run(os.Args) } ``` The default flag may be customized to something other than `-h/--help` by setting `cli.HelpFlag`, e.g.: ``` go package main import ( "os" "github.com/urfave/cli" ) func main() { cli.HelpFlag = cli.BoolFlag{ Name: "halp, haaaaalp", Usage: "HALP", EnvVar: "SHOW_HALP,HALPPLZ", } cli.NewApp().Run(os.Args) } ``` ### Version Flag The default version flag (`-v/--version`) is defined as `cli.VersionFlag`, which is checked by the cli internals in order to print the `App.Version` via `cli.VersionPrinter` and break execution. #### Customization The default flag may be customized to something other than `-v/--version` by setting `cli.VersionFlag`, e.g.: ``` go package main import ( "os" "github.com/urfave/cli" ) func main() { cli.VersionFlag = cli.BoolFlag{ Name: "print-version, V", Usage: "print only the version", } app := cli.NewApp() app.Name = "partay" app.Version = "19.99.0" app.Run(os.Args) } ``` Alternatively, the version printer at `cli.VersionPrinter` may be overridden, e.g.: ``` go package main import ( "fmt" "os" "github.com/urfave/cli" ) var ( Revision = "fafafaf" ) func main() { cli.VersionPrinter = func(c *cli.Context) { fmt.Printf("version=%s revision=%s\n", c.App.Version, Revision) } app := cli.NewApp() app.Name = "partay" app.Version = "19.99.0" app.Run(os.Args) } ``` #### Full API Example **Notice**: This is a contrived (functioning) example meant strictly for API demonstration purposes. Use of one's imagination is encouraged. ``` go package main import ( "errors" "flag" "fmt" "io" "io/ioutil" "os" "time" "github.com/urfave/cli" ) func init() { cli.AppHelpTemplate += "\nCUSTOMIZED: you bet ur muffins\n" cli.CommandHelpTemplate += "\nYMMV\n" cli.SubcommandHelpTemplate += "\nor something\n" cli.HelpFlag = cli.BoolFlag{Name: "halp"} cli.BashCompletionFlag = cli.BoolFlag{Name: "compgen", Hidden: true} cli.VersionFlag = cli.BoolFlag{Name: "print-version, V"} cli.HelpPrinter = func(w io.Writer, templ string, data interface{}) { fmt.Fprintf(w, "best of luck to you\n") } cli.VersionPrinter = func(c *cli.Context) { fmt.Fprintf(c.App.Writer, "version=%s\n", c.App.Version) } cli.OsExiter = func(c int) { fmt.Fprintf(cli.ErrWriter, "refusing to exit %d\n", c) } cli.ErrWriter = ioutil.Discard cli.FlagStringer = func(fl cli.Flag) string { return fmt.Sprintf("\t\t%s", fl.GetName()) } } type hexWriter struct{} func (w *hexWriter) Write(p []byte) (int, error) { for _, b := range p { fmt.Printf("%x", b) } fmt.Printf("\n") return len(p), nil } type genericType struct{ s string } func (g *genericType) Set(value string) error { g.s = value return nil } func (g *genericType) String() string { return g.s } func main() { app := cli.NewApp() app.Name = "kənˈtrīv" app.Version = "19.99.0" app.Compiled = time.Now() app.Authors = []cli.Author{ cli.Author{ Name: "Example Human", Email: "human@example.com", }, } app.Copyright = "(c) 1999 Serious Enterprise" app.HelpName = "contrive" app.Usage = "demonstrate available API" app.UsageText = "contrive - demonstrating the available API" app.ArgsUsage = "[args and such]" app.Commands = []cli.Command{ cli.Command{ Name: "doo", Aliases: []string{"do"}, Category: "motion", Usage: "do the doo", UsageText: "doo - does the dooing", Description: "no really, there is a lot of dooing to be done", ArgsUsage: "[arrgh]", Flags: []cli.Flag{ cli.BoolFlag{Name: "forever, forevvarr"}, }, Subcommands: cli.Commands{ cli.Command{ Name: "wop", Action: wopAction, }, }, SkipFlagParsing: false, HideHelp: false, Hidden: false, HelpName: "doo!", BashComplete: func(c *cli.Context) { fmt.Fprintf(c.App.Writer, "--better\n") }, Before: func(c *cli.Context) error { fmt.Fprintf(c.App.Writer, "brace for impact\n") return nil }, After: func(c *cli.Context) error { fmt.Fprintf(c.App.Writer, "did we lose anyone?\n") return nil }, Action: func(c *cli.Context) error { c.Command.FullName() c.Command.HasName("wop") c.Command.Names() c.Command.VisibleFlags() fmt.Fprintf(c.App.Writer, "dodododododoodododddooooododododooo\n") if c.Bool("forever") { c.Command.Run(c) } return nil }, OnUsageError: func(c *cli.Context, err error, isSubcommand bool) error { fmt.Fprintf(c.App.Writer, "for shame\n") return err }, }, } app.Flags = []cli.Flag{ cli.BoolFlag{Name: "fancy"}, cli.BoolTFlag{Name: "fancier"}, cli.DurationFlag{Name: "howlong, H", Value: time.Second * 3}, cli.Float64Flag{Name: "howmuch"}, cli.GenericFlag{Name: "wat", Value: &genericType{}}, cli.Int64Flag{Name: "longdistance"}, cli.Int64SliceFlag{Name: "intervals"}, cli.IntFlag{Name: "distance"}, cli.IntSliceFlag{Name: "times"}, cli.StringFlag{Name: "dance-move, d"}, cli.StringSliceFlag{Name: "names, N"}, cli.UintFlag{Name: "age"}, cli.Uint64Flag{Name: "bigage"}, } app.EnableBashCompletion = true app.HideHelp = false app.HideVersion = false app.BashComplete = func(c *cli.Context) { fmt.Fprintf(c.App.Writer, "lipstick\nkiss\nme\nlipstick\nringo\n") } app.Before = func(c *cli.Context) error { fmt.Fprintf(c.App.Writer, "HEEEERE GOES\n") return nil } app.After = func(c *cli.Context) error { fmt.Fprintf(c.App.Writer, "Phew!\n") return nil } app.CommandNotFound = func(c *cli.Context, command string) { fmt.Fprintf(c.App.Writer, "Thar be no %q here.\n", command) } app.OnUsageError = func(c *cli.Context, err error, isSubcommand bool) error { if isSubcommand { return err } fmt.Fprintf(c.App.Writer, "WRONG: %#v\n", err) return nil } app.Action = func(c *cli.Context) error { cli.DefaultAppComplete(c) cli.HandleExitCoder(errors.New("not an exit coder, though")) cli.ShowAppHelp(c) cli.ShowCommandCompletions(c, "nope") cli.ShowCommandHelp(c, "also-nope") cli.ShowCompletions(c) cli.ShowSubcommandHelp(c) cli.ShowVersion(c) categories := c.App.Categories() categories.AddCommand("sounds", cli.Command{ Name: "bloop", }) for _, category := range c.App.Categories() { fmt.Fprintf(c.App.Writer, "%s\n", category.Name) fmt.Fprintf(c.App.Writer, "%#v\n", category.Commands) fmt.Fprintf(c.App.Writer, "%#v\n", category.VisibleCommands()) } fmt.Printf("%#v\n", c.App.Command("doo")) if c.Bool("infinite") { c.App.Run([]string{"app", "doo", "wop"}) } if c.Bool("forevar") { c.App.RunAsSubcommand(c) } c.App.Setup() fmt.Printf("%#v\n", c.App.VisibleCategories()) fmt.Printf("%#v\n", c.App.VisibleCommands()) fmt.Printf("%#v\n", c.App.VisibleFlags()) fmt.Printf("%#v\n", c.Args().First()) if len(c.Args()) > 0 { fmt.Printf("%#v\n", c.Args()[1]) } fmt.Printf("%#v\n", c.Args().Present()) fmt.Printf("%#v\n", c.Args().Tail()) set := flag.NewFlagSet("contrive", 0) nc := cli.NewContext(c.App, set, c) fmt.Printf("%#v\n", nc.Args()) fmt.Printf("%#v\n", nc.Bool("nope")) fmt.Printf("%#v\n", nc.BoolT("nerp")) fmt.Printf("%#v\n", nc.Duration("howlong")) fmt.Printf("%#v\n", nc.Float64("hay")) fmt.Printf("%#v\n", nc.Generic("bloop")) fmt.Printf("%#v\n", nc.Int64("bonk")) fmt.Printf("%#v\n", nc.Int64Slice("burnks")) fmt.Printf("%#v\n", nc.Int("bips")) fmt.Printf("%#v\n", nc.IntSlice("blups")) fmt.Printf("%#v\n", nc.String("snurt")) fmt.Printf("%#v\n", nc.StringSlice("snurkles")) fmt.Printf("%#v\n", nc.Uint("flub")) fmt.Printf("%#v\n", nc.Uint64("florb")) fmt.Printf("%#v\n", nc.GlobalBool("global-nope")) fmt.Printf("%#v\n", nc.GlobalBoolT("global-nerp")) fmt.Printf("%#v\n", nc.GlobalDuration("global-howlong")) fmt.Printf("%#v\n", nc.GlobalFloat64("global-hay")) fmt.Printf("%#v\n", nc.GlobalGeneric("global-bloop")) fmt.Printf("%#v\n", nc.GlobalInt("global-bips")) fmt.Printf("%#v\n", nc.GlobalIntSlice("global-blups")) fmt.Printf("%#v\n", nc.GlobalString("global-snurt")) fmt.Printf("%#v\n", nc.GlobalStringSlice("global-snurkles")) fmt.Printf("%#v\n", nc.FlagNames()) fmt.Printf("%#v\n", nc.GlobalFlagNames()) fmt.Printf("%#v\n", nc.GlobalIsSet("wat")) fmt.Printf("%#v\n", nc.GlobalSet("wat", "nope")) fmt.Printf("%#v\n", nc.NArg()) fmt.Printf("%#v\n", nc.NumFlags()) fmt.Printf("%#v\n", nc.Parent()) nc.Set("wat", "also-nope") ec := cli.NewExitError("ohwell", 86) fmt.Fprintf(c.App.Writer, "%d", ec.ExitCode()) fmt.Printf("made it!\n") return ec } if os.Getenv("HEXY") != "" { app.Writer = &hexWriter{} app.ErrWriter = &hexWriter{} } app.Metadata = map[string]interface{}{ "layers": "many", "explicable": false, "whatever-values": 19.99, } app.Run(os.Args) } func wopAction(c *cli.Context) error { fmt.Fprintf(c.App.Writer, ":wave: over here, eh\n") return nil } ``` ### Combining short Bool options Traditional use of boolean options using their shortnames look like this: ``` # cmd foobar -s -o ``` Suppose you want users to be able to combine your bool options with their shortname. This can be done using the **UseShortOptionHandling** bool in your commands. Suppose your program has a two bool flags such as *serve* and *option* with the short options of *-o* and *-s* respectively. With **UseShortOptionHandling** set to *true*, a user can use a syntax like: ``` # cmd foobar -so ``` If you enable the **UseShortOptionHandling*, then you must not use any flags that have a single leading *-* or this will result in failures. For example, **-option** can no longer be used. Flags with two leading dashes (such as **--options**) are still valid. ## Contribution Guidelines Feel free to put up a pull request to fix a bug or maybe add a feature. I will give it a code review and make sure that it does not break backwards compatibility. If I or any other collaborators agree that it is in line with the vision of the project, we will work with you to get the code into a mergeable state and merge it into the master branch. If you have contributed something significant to the project, we will most likely add you as a collaborator. As a collaborator you are given the ability to merge others pull requests. It is very important that new code does not break existing code, so be careful about what code you do choose to merge. If you feel like you have contributed to the project but have not yet been added as a collaborator, we probably forgot to add you, please open an issue.