cli

README

cli

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
• Installation
  • Supported platforms
  • Using the v2 branch
  • Using v1 releases
• Getting Started
• Examples
  • Arguments
  • Flags
    • Placeholder Values
    • Alternate Names
    • Ordering
    • Values from the Environment
    • Values from files
    • Values from alternate input sources (YAML, TOML, and others)
    • Precedence
  • Subcommands
  • Subcommands categories
  • Exit code
  • Combining short options
  • Bash Completion
    • Enabling
    • Distribution
    • Customization
  • Generated Help Text
    • Customization
  • Version Flag
    • Customization
    • Full API Example
• 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 1.10+ is supported. See the install instructions for Go.

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 and ./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

...
import (
  "gopkg.in/urfave/cli.v2" // imports as package "cli"
)
...

Using v1 releases

$ go get github.com/urfave/cli

...
import (
  "github.com/urfave/cli"
)
...

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().

package main

import (
  "log"
  "os"

  "github.com/urfave/cli"
)

func main() {
  err := cli.NewApp().Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

This app will run and show help text, but is not very useful. Let's give an action to execute and some help documentation:

package main

import (
  "fmt"
  "log"
  "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
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

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:

package main

import (
  "fmt"
  "log"
  "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
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

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.:

package main

import (
  "fmt"
  "log"
  "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
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

Flags

Setting and querying flags is simple.

package main

import (
  "fmt"
  "log"
  "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
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

You can also set a destination variable for a flag, to which the content will be scanned.

package main

import (
  "log"
  "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
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

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:

package main

import (
  "log"
  "os"

  "github.com/urfave/cli"
)

func main() {
  app := cli.NewApp()

  app.Flags = []cli.Flag{
    cli.StringFlag{
      Name:  "config, c",
      Usage: "Load configuration from `FILE`",
    },
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

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.

package main

import (
  "log"
  "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",
    },
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

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:

package main

import (
  "log"
  "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))

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

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.

package main

import (
  "log"
  "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",
    },
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

The EnvVar may also be given as a comma-delimited "cascade", where the first environment variable that resolves is used as the default.

package main

import (
  "log"
  "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",
    },
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

Values from files

You can also have the default value set from file via FilePath. e.g.

package main

import (
  "log"
  "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",
    },
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

Note that default values set from file (e.g. FilePath) take precedence over default values set from the environment (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
• JSON
• 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:

  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.

  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 YAML, JSON, and TOML files 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:

package notmain

import (
  "fmt"
  "log"
  "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

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

Precedence

The precedence for flag value sources is as follows (highest to lowest):

1. Command line flag value from user
2. Environment variable (if specified)
3. Configuration file (if specified)
4. Default defined on the flag

Subcommands

Subcommands can be defined for a more git-like command line app.

package main

import (
  "fmt"
  "log"
  "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
          },
        },
      },
    },
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

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.

package main

import (
  "log"
  "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",
    },
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

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.:

package main

import (
  "log"
  "os"

  "github.com/urfave/cli"
)

func main() {
  app := cli.NewApp()
  app.Flags = []cli.Flag{
    cli.BoolFlag{
      Name:  "ginger-crouton",
      Usage: "Add ginger croutons to the soup",
    },
  }
  app.Action = func(ctx *cli.Context) error {
    if !ctx.Bool("ginger-crouton") {
      return cli.NewExitError("Ginger croutons are not in the soup", 86)
    }
    return nil
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

Combining short options

Traditional use of options using their shortnames look like this:

$ cmd -s -o -m "Some message"

Suppose you want users to be able to combine options with their shortnames. This can be done using the UseShortOptionHandling bool in your app configuration, or for individual commands by attaching it to the command configuration. For example:

package main

import (
  "fmt"
  "log"
  "os"

  "github.com/urfave/cli"
)

func main() {
  app := cli.NewApp()
  app.UseShortOptionHandling = true
  app.Commands = []cli.Command{
    {
      Name:  "short",
      Usage: "complete a task on the list",
      Flags: []cli.Flag{
        cli.BoolFlag{Name: "serve, s"},
        cli.BoolFlag{Name: "option, o"},
        cli.StringFlag{Name: "message, m"},
      },
      Action: func(c *cli.Context) error {
        fmt.Println("serve:", c.Bool("serve"))
        fmt.Println("option:", c.Bool("option"))
        fmt.Println("message:", c.String("message"))
        return nil
      },
    },
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

If your program has any number of bool flags such as serve and option, and optionally one non-bool flag message, with the short options of -s, -o, and -m respectively, setting UseShortOptionHandling will also support the following syntax:

$ cmd -som "Some message"

If you enable 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.

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.

package main

import (
  "fmt"
  "log"
  "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)
        }
      },
    },
  }

  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

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/<myprogram>
source /etc/bash_completion.d/<myprogram>

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.:

package main

import (
  "log"
  "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",
    },
  }
  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

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.:

package main

import (
  "fmt"
  "log"
  "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")
  }

  err := cli.NewApp().Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

The default flag may be customized to something other than -h/--help by setting cli.HelpFlag, e.g.:

package main

import (
  "log"
  "os"

  "github.com/urfave/cli"
)

func main() {
  cli.HelpFlag = cli.BoolFlag{
    Name: "halp, haaaaalp",
    Usage: "HALP",
    EnvVar: "SHOW_HALP,HALPPLZ",
  }

  err := cli.NewApp().Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

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.:

package main

import (
  "log"
  "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"
  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

Alternatively, the version printer at cli.VersionPrinter may be overridden, e.g.:

package main

import (
  "fmt"
  "log"
  "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"
  err := app.Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

Full API Example

Notice: This is a contrived (functioning) example meant strictly for API demonstration purposes. Use of one's imagination is encouraged.

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.UseShortOptionHandling = 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 nil
  }

  if os.Getenv("HEXY") != "" {
    app.Writer = &hexWriter{}
    app.ErrWriter = &hexWriter{}
  }

  app.Metadata = map[string]interface{}{
    "layers":     "many",
    "explicable": false,
    "whatever-values": 19.99,
  }


  // ignore error so we don't exit non-zero and break gfmrun README example tests
  _ = app.Run(os.Args)
}

func wopAction(c *cli.Context) error {
  fmt.Fprintf(c.App.Writer, ":wave: over here, eh\n")
  return nil
}

Contribution Guidelines

See ./CONTRIBUTING.md

Documentation

Overview

Package cli provides a minimal framework for creating and organizing command line Go applications. cli is designed to be easy to understand and write, the most simple cli application can be written as follows:

func main() {
  cli.NewApp().Run(os.Args)
}

Of course this application does not do much, so let's make this an actual application:

func main() {
  app := cli.NewApp()
  app.Name = "greet"
  app.Usage = "say a greeting"
  app.Action = func(c *cli.Context) error {
    println("Greetings")
    return nil
  }

  app.Run(os.Args)
}

Index

• Variables
• func DefaultAppComplete(c *Context)
• func DefaultCompleteWithFlags(cmd *Command) func(c *Context)
• func HandleAction(action interface{}, context *Context) (err error)
• func HandleExitCoder(err error)
• func ShowAppHelp(c *Context) (err error)
• func ShowAppHelpAndExit(c *Context, exitCode int)
• func ShowCommandCompletions(ctx *Context, command string)
• func ShowCommandHelp(ctx *Context, command string) error
• func ShowCommandHelpAndExit(c *Context, command string, code int)
• func ShowCompletions(c *Context)
• func ShowSubcommandHelp(c *Context) error
• func ShowVersion(c *Context)
• type ActionFunc
• type AfterFunc
• type App
  • func NewApp() *App
  • func (a *App) Categories() CommandCategories
  • func (a *App) Command(name string) *Command
  • func (a *App) Run(arguments []string) (err error)
  • func (a *App) RunAndExitOnError()
  • func (a *App) RunAsSubcommand(ctx *Context) (err error)
  • func (a *App) Setup()
  • func (a *App) ToFishCompletion() (string, error)
  • func (a *App) ToMan() (string, error)
  • func (a *App) ToMarkdown() (string, error)
  • func (a *App) VisibleCategories() []*CommandCategory
  • func (a *App) VisibleCommands() []Command
  • func (a *App) VisibleFlags() []Flag
• type Args
  • func (a Args) First() string
  • func (a Args) Get(n int) string
  • func (a Args) Present() bool
  • func (a Args) Swap(from, to int) error
  • func (a Args) Tail() []string
• type Author
  • func (a Author) String() string
• type BashCompleteFunc
• type BeforeFunc
• type BoolFlag
  • func (f BoolFlag) Apply(set *flag.FlagSet)
  • func (f BoolFlag) ApplyWithError(set *flag.FlagSet) error
  • func (f BoolFlag) GetName() string
  • func (f BoolFlag) GetUsage() string
  • func (f BoolFlag) GetValue() string
  • func (f BoolFlag) IsRequired() bool
  • func (f BoolFlag) String() string
  • func (f BoolFlag) TakesValue() bool
• type BoolTFlag
  • func (f BoolTFlag) Apply(set *flag.FlagSet)
  • func (f BoolTFlag) ApplyWithError(set *flag.FlagSet) error
  • func (f BoolTFlag) GetName() string
  • func (f BoolTFlag) GetUsage() string
  • func (f BoolTFlag) GetValue() string
  • func (f BoolTFlag) IsRequired() bool
  • func (f BoolTFlag) String() string
  • func (f BoolTFlag) TakesValue() bool
• type Command
  • func (c Command) FullName() string
  • func (c Command) HasName(name string) bool
  • func (c Command) Names() []string
  • func (c Command) Run(ctx *Context) (err error)
  • func (c Command) VisibleFlags() []Flag
• type CommandCategories
  • func (c CommandCategories) AddCommand(category string, command Command) CommandCategories
  • func (c CommandCategories) Len() int
  • func (c CommandCategories) Less(i, j int) bool
  • func (c CommandCategories) Swap(i, j int)
• type CommandCategory
  • func (c *CommandCategory) VisibleCommands() []Command
• type CommandNotFoundFunc
• type Commands
• type CommandsByName
  • func (c CommandsByName) Len() int
  • func (c CommandsByName) Less(i, j int) bool
  • func (c CommandsByName) Swap(i, j int)
• type Context
  • func NewContext(app *App, set *flag.FlagSet, parentCtx *Context) *Context
  • func (c *Context) Args() Args
  • func (c *Context) Bool(name string) bool
  • func (c *Context) BoolT(name string) bool
  • func (c *Context) Duration(name string) time.Duration
  • func (c *Context) FlagNames() (names []string)
  • func (c *Context) Float64(name string) float64
  • func (c *Context) Generic(name string) interface{}
  • func (c *Context) GlobalBool(name string) bool
  • func (c *Context) GlobalBoolT(name string) bool
  • func (c *Context) GlobalDuration(name string) time.Duration
  • func (c *Context) GlobalFlagNames() (names []string)
  • func (c *Context) GlobalFloat64(name string) float64
  • func (c *Context) GlobalGeneric(name string) interface{}
  • func (c *Context) GlobalInt(name string) int
  • func (c *Context) GlobalInt64(name string) int64
  • func (c *Context) GlobalInt64Slice(name string) []int64
  • func (c *Context) GlobalIntSlice(name string) []int
  • func (c *Context) GlobalIsSet(name string) bool
  • func (c *Context) GlobalSet(name, value string) error
  • func (c *Context) GlobalString(name string) string
  • func (c *Context) GlobalStringSlice(name string) []string
  • func (c *Context) GlobalUint(name string) uint
  • func (c *Context) GlobalUint64(name string) uint64
  • func (c *Context) Int(name string) int
  • func (c *Context) Int64(name string) int64
  • func (c *Context) Int64Slice(name string) []int64
  • func (c *Context) IntSlice(name string) []int
  • func (c *Context) IsSet(name string) bool
  • func (c *Context) NArg() int
  • func (c *Context) NumFlags() int
  • func (c *Context) Parent() *Context
  • func (c *Context) Set(name, value string) error
  • func (c *Context) String(name string) string
  • func (c *Context) StringSlice(name string) []string
  • func (c *Context) Uint(name string) uint
  • func (c *Context) Uint64(name string) uint64
• type DocGenerationFlag
• type DurationFlag
  • func (f DurationFlag) Apply(set *flag.FlagSet)
  • func (f DurationFlag) ApplyWithError(set *flag.FlagSet) error
  • func (f DurationFlag) GetName() string
  • func (f DurationFlag) GetUsage() string
  • func (f DurationFlag) GetValue() string
  • func (f DurationFlag) IsRequired() bool
  • func (f DurationFlag) String() string
  • func (f DurationFlag) TakesValue() bool
• type ErrorFormatter
• type ExitCoder
• type ExitErrHandlerFunc
• type ExitError
  • func NewExitError(message interface{}, exitCode int) *ExitError
  • func (ee *ExitError) Error() string
  • func (ee *ExitError) ExitCode() int
• type Flag
• type FlagEnvHintFunc
• type FlagFileHintFunc
• type FlagNamePrefixFunc
• type FlagStringFunc
• type FlagsByName
  • func (f FlagsByName) Len() int
  • func (f FlagsByName) Less(i, j int) bool
  • func (f FlagsByName) Swap(i, j int)
• type Float64Flag
  • func (f Float64Flag) Apply(set *flag.FlagSet)
  • func (f Float64Flag) ApplyWithError(set *flag.FlagSet) error
  • func (f Float64Flag) GetName() string
  • func (f Float64Flag) GetUsage() string
  • func (f Float64Flag) GetValue() string
  • func (f Float64Flag) IsRequired() bool
  • func (f Float64Flag) String() string
  • func (f Float64Flag) TakesValue() bool
• type Generic
• type GenericFlag
  • func (f GenericFlag) Apply(set *flag.FlagSet)
  • func (f GenericFlag) ApplyWithError(set *flag.FlagSet) error
  • func (f GenericFlag) GetName() string
  • func (f GenericFlag) GetUsage() string
  • func (f GenericFlag) GetValue() string
  • func (f GenericFlag) IsRequired() bool
  • func (f GenericFlag) String() string
  • func (f GenericFlag) TakesValue() bool
• type Int64Flag
  • func (f Int64Flag) Apply(set *flag.FlagSet)
  • func (f Int64Flag) ApplyWithError(set *flag.FlagSet) error
  • func (f Int64Flag) GetName() string
  • func (f Int64Flag) GetUsage() string
  • func (f Int64Flag) GetValue() string
  • func (f Int64Flag) IsRequired() bool
  • func (f Int64Flag) String() string
  • func (f Int64Flag) TakesValue() bool
• type Int64Slice
  • func (f *Int64Slice) Get() interface{}
  • func (f *Int64Slice) Set(value string) error
  • func (f *Int64Slice) String() string
  • func (f *Int64Slice) Value() []int64
• type Int64SliceFlag
  • func (f Int64SliceFlag) Apply(set *flag.FlagSet)
  • func (f Int64SliceFlag) ApplyWithError(set *flag.FlagSet) error
  • func (f Int64SliceFlag) GetName() string
  • func (f Int64SliceFlag) GetUsage() string
  • func (f Int64SliceFlag) GetValue() string
  • func (f Int64SliceFlag) IsRequired() bool
  • func (f Int64SliceFlag) String() string
  • func (f Int64SliceFlag) TakesValue() bool
• type IntFlag
  • func (f IntFlag) Apply(set *flag.FlagSet)
  • func (f IntFlag) ApplyWithError(set *flag.FlagSet) error
  • func (f IntFlag) GetName() string
  • func (f IntFlag) GetUsage() string
  • func (f IntFlag) GetValue() string
  • func (f IntFlag) IsRequired() bool
  • func (f IntFlag) String() string
  • func (f IntFlag) TakesValue() bool
• type IntSlice
  • func (f *IntSlice) Get() interface{}
  • func (f *IntSlice) Set(value string) error
  • func (f *IntSlice) String() string
  • func (f *IntSlice) Value() []int
• type IntSliceFlag
  • func (f IntSliceFlag) Apply(set *flag.FlagSet)
  • func (f IntSliceFlag) ApplyWithError(set *flag.FlagSet) error
  • func (f IntSliceFlag) GetName() string
  • func (f IntSliceFlag) GetUsage() string
  • func (f IntSliceFlag) GetValue() string
  • func (f IntSliceFlag) IsRequired() bool
  • func (f IntSliceFlag) String() string
  • func (f IntSliceFlag) TakesValue() bool
• type MultiError
  • func NewMultiError(err ...error) MultiError
  • func (m MultiError) Error() string
• type OnUsageErrorFunc
• type RequiredFlag
• type StringFlag
  • func (f StringFlag) Apply(set *flag.FlagSet)
  • func (f StringFlag) ApplyWithError(set *flag.FlagSet) error
  • func (f StringFlag) GetName() string
  • func (f StringFlag) GetUsage() string
  • func (f StringFlag) GetValue() string
  • func (f StringFlag) IsRequired() bool
  • func (f StringFlag) String() string
  • func (f StringFlag) TakesValue() bool
• type StringSlice
  • func (f *StringSlice) Get() interface{}
  • func (f *StringSlice) Set(value string) error
  • func (f *StringSlice) String() string
  • func (f *StringSlice) Value() []string
• type StringSliceFlag
  • func (f StringSliceFlag) Apply(set *flag.FlagSet)
  • func (f StringSliceFlag) ApplyWithError(set *flag.FlagSet) error
  • func (f StringSliceFlag) GetName() string
  • func (f StringSliceFlag) GetUsage() string
  • func (f StringSliceFlag) GetValue() string
  • func (f StringSliceFlag) IsRequired() bool
  • func (f StringSliceFlag) String() string
  • func (f StringSliceFlag) TakesValue() bool
• type Uint64Flag
  • func (f Uint64Flag) Apply(set *flag.FlagSet)
  • func (f Uint64Flag) ApplyWithError(set *flag.FlagSet) error
  • func (f Uint64Flag) GetName() string
  • func (f Uint64Flag) GetUsage() string
  • func (f Uint64Flag) GetValue() string
  • func (f Uint64Flag) IsRequired() bool
  • func (f Uint64Flag) String() string
  • func (f Uint64Flag) TakesValue() bool
• type UintFlag
  • func (f UintFlag) Apply(set *flag.FlagSet)
  • func (f UintFlag) ApplyWithError(set *flag.FlagSet) error
  • func (f UintFlag) GetName() string
  • func (f UintFlag) GetUsage() string
  • func (f UintFlag) GetValue() string
  • func (f UintFlag) IsRequired() bool
  • func (f UintFlag) String() string
  • func (f UintFlag) TakesValue() bool

Examples

• App.Run
• App.Run (AppHelp)
• App.Run (BashComplete)
• App.Run (BashComplete_withLongFlag)
• App.Run (BashComplete_withMultipleLongFlag)
• App.Run (BashComplete_withShortFlag)
• App.Run (CommandHelp)
• App.Run (NoAction)
• App.Run (Subcommand)
• App.Run (SubcommandNoAction)
• App.Run (ZshComplete)

Variables

var AppHelpTemplate = `` /* 1055-byte string literal not displayed */

AppHelpTemplate is the text template for the Default help topic. cli.go uses text/template to render templates. You can render custom help text by setting this variable.

var CommandHelpTemplate = `` /* 404-byte string literal not displayed */

CommandHelpTemplate is the text template for the command help topic. cli.go uses text/template to render templates. You can render custom help text by setting this variable.

var ErrWriter io.Writer = os.Stderr

ErrWriter is used to write errors to the user. This can be anything implementing the io.Writer interface and defaults to os.Stderr.

var FishCompletionTemplate = `` /* 358-byte string literal not displayed */

var HelpPrinter helpPrinter = printHelp

HelpPrinter is a function that writes the help output. If not set a default is used. The function signature is: func(w io.Writer, templ string, data interface{})

var HelpPrinterCustom helpPrinterCustom = printHelpCustom

HelpPrinterCustom is same as HelpPrinter but takes a custom function for template function map.

var MarkdownDocTemplate = `% {{ .App.Name }}(8) {{ .App.Description }}

% {{ .App.Author }}

# NAME

{{ .App.Name }}{{ if .App.Usage }} - {{ .App.Usage }}{{ end }}

# SYNOPSIS

{{ .App.Name }}
{{ if .SynopsisArgs }}
` + "```" + `
{{ range $v := .SynopsisArgs }}{{ $v }}{{ end }}` + "```" + `
{{ end }}{{ if .App.UsageText }}
# DESCRIPTION

{{ .App.UsageText }}
{{ end }}
**Usage**:

` + "```" + `
{{ .App.Name }} [GLOBAL OPTIONS] command [COMMAND OPTIONS] [ARGUMENTS...]
` + "```" + `
{{ if .GlobalArgs }}
# GLOBAL OPTIONS
{{ range $v := .GlobalArgs }}
{{ $v }}{{ end }}
{{ end }}{{ if .Commands }}
# COMMANDS
{{ range $v := .Commands }}
{{ $v }}{{ end }}{{ end }}`

var OsExiter = os.Exit

OsExiter is the function used when the app exits. If not set defaults to os.Exit.

var SubcommandHelpTemplate = `` /* 591-byte string literal not displayed */

SubcommandHelpTemplate is the text template for the subcommand help topic. cli.go uses text/template to render templates. You can render custom help text by setting this variable.

var VersionPrinter = printVersion

VersionPrinter prints the version for the App

Functions

func DefaultAppComplete

func DefaultAppComplete(c *Context)

DefaultAppComplete prints the list of subcommands as the default app completion method

func DefaultCompleteWithFlags

func DefaultCompleteWithFlags(cmd *Command) func(c *Context)

func HandleAction

func HandleAction(action interface{}, context *Context) (err error)

HandleAction attempts to figure out which Action signature was used. If it's an ActionFunc or a func with the legacy signature for Action, the func is run!

func HandleExitCoder

func HandleExitCoder(err error)

HandleExitCoder checks if the error fulfills the ExitCoder interface, and if so prints the error to stderr (if it is non-empty) and calls OsExiter with the given exit code. If the given error is a MultiError, then this func is called on all members of the Errors slice and calls OsExiter with the last exit code.

func ShowAppHelp

func ShowAppHelp(c *Context) (err error)

ShowAppHelp is an action that displays the help.

func ShowAppHelpAndExit

func ShowAppHelpAndExit(c *Context, exitCode int)

ShowAppHelpAndExit - Prints the list of subcommands for the app and exits with exit code.

func ShowCommandCompletions

func ShowCommandCompletions(ctx *Context, command string)

ShowCommandCompletions prints the custom completions for a given command

func ShowCommandHelp

func ShowCommandHelp(ctx *Context, command string) error

ShowCommandHelp prints help for the given command

func ShowCommandHelpAndExit

func ShowCommandHelpAndExit(c *Context, command string, code int)

ShowCommandHelpAndExit - exits with code after showing help

func ShowCompletions

func ShowCompletions(c *Context)

ShowCompletions prints the lists of commands within a given context

func ShowSubcommandHelp

func ShowSubcommandHelp(c *Context) error

ShowSubcommandHelp prints help for the given subcommand

func ShowVersion

func ShowVersion(c *Context)

ShowVersion prints the version number of the App

Types

type ActionFunc

type ActionFunc func(*Context) error

ActionFunc is the action to execute when no subcommands are specified

type AfterFunc

type AfterFunc func(*Context) error

AfterFunc is an action to execute after any subcommands are run, but after the subcommand has finished it is run even if Action() panics

type App

type App struct {
	// The name of the program. Defaults to path.Base(os.Args[0])
	Name string
	// Full name of command for help, defaults to Name
	HelpName string
	// Description of the program.
	Usage string
	// Text to override the USAGE section of help
	UsageText string
	// Description of the program argument format.
	ArgsUsage string
	// Version of the program
	Version string
	// Description of the program
	Description string
	// List of commands to execute
	Commands []Command
	// List of flags to parse
	Flags []Flag
	// Boolean to enable bash completion commands
	EnableBashCompletion bool
	// Boolean to hide built-in help command
	HideHelp bool
	// Boolean to hide built-in version flag and the VERSION section of help
	HideVersion bool

	// An action to execute when the bash-completion flag is set
	BashComplete BashCompleteFunc
	// An action to execute before any subcommands are run, but after the context is ready
	// If a non-nil error is returned, no subcommands are run
	Before BeforeFunc
	// An action to execute after any subcommands are run, but after the subcommand has finished
	// It is run even if Action() panics
	After AfterFunc

	// The action to execute when no subcommands are specified
	// Expects a `cli.ActionFunc` but will accept the *deprecated* signature of `func(*cli.Context) {}`
	// *Note*: support for the deprecated `Action` signature will be removed in a future version
	Action interface{}

	// Execute this function if the proper command cannot be found
	CommandNotFound CommandNotFoundFunc
	// Execute this function if an usage error occurs
	OnUsageError OnUsageErrorFunc
	// Compilation date
	Compiled time.Time
	// List of all authors who contributed
	Authors []Author
	// Copyright of the binary if any
	Copyright string
	// Name of Author (Note: Use App.Authors, this is deprecated)
	Author string
	// Email of Author (Note: Use App.Authors, this is deprecated)
	Email string
	// Writer writer to write output to
	Writer io.Writer
	// ErrWriter writes error output
	ErrWriter io.Writer
	// Execute this function to handle ExitErrors. If not provided, HandleExitCoder is provided to
	// function as a default, so this is optional.
	ExitErrHandler ExitErrHandlerFunc
	// Other custom info
	Metadata map[string]interface{}
	// Carries a function which returns app specific info.
	ExtraInfo func() map[string]string
	// CustomAppHelpTemplate the text template for app help topic.
	// cli.go uses text/template to render templates. You can
	// render custom help text by setting this variable.
	CustomAppHelpTemplate string
	// Boolean to enable short-option handling so user can combine several
	// single-character bool arguements into one
	// i.e. foobar -o -v -> foobar -ov
	UseShortOptionHandling bool
	// contains filtered or unexported fields
}

App is the main structure of a cli application. It is recommended that an app be created with the cli.NewApp() function

func NewApp

func NewApp() *App

NewApp creates a new cli Application with some reasonable defaults for Name, Usage, Version and Action.

func (*App) Categories

func (a *App) Categories() CommandCategories

Categories returns a slice containing all the categories with the commands they contain

func (*App) Command

func (a *App) Command(name string) *Command

Command returns the named command on App. Returns nil if the command does not exist

func (*App) Run

func (a *App) Run(arguments []string) (err error)

Run is the entry point to the cli app. Parses the arguments slice and routes to the proper flag/args combination

Example

// set args for examples sake
os.Args = []string{"greet", "--name", "Jeremy"}

app := NewApp()
app.Name = "greet"
app.Flags = []Flag{
	StringFlag{Name: "name", Value: "bob", Usage: "a name to say"},
}
app.Action = func(c *Context) error {
	fmt.Printf("Hello %v\n", c.String("name"))
	return nil
}
app.UsageText = "app [first_arg] [second_arg]"
app.Author = "Harrison"
app.Email = "harrison@lolwut.com"
app.Authors = []Author{{Name: "Oliver Allen", Email: "oliver@toyshop.com"}}
_ = app.Run(os.Args)

Output:

Hello Jeremy

Example (AppHelp)

// set args for examples sake
os.Args = []string{"greet", "help"}

app := NewApp()
app.Name = "greet"
app.Version = "0.1.0"
app.Description = "This is how we describe greet the app"
app.Authors = []Author{
	{Name: "Harrison", Email: "harrison@lolwut.com"},
	{Name: "Oliver Allen", Email: "oliver@toyshop.com"},
}
app.Flags = []Flag{
	StringFlag{Name: "name", Value: "bob", Usage: "a name to say"},
}
app.Commands = []Command{
	{
		Name:        "describeit",
		Aliases:     []string{"d"},
		Usage:       "use it to see a description",
		Description: "This is how we describe describeit the function",
		Action: func(c *Context) error {
			fmt.Printf("i like to describe things")
			return nil
		},
	},
}
_ = app.Run(os.Args)

Output:

NAME:
   greet - A new cli application

USAGE:
   greet [global options] command [command options] [arguments...]

VERSION:
   0.1.0

DESCRIPTION:
   This is how we describe greet the app

AUTHORS:
   Harrison <harrison@lolwut.com>
   Oliver Allen <oliver@toyshop.com>

COMMANDS:
   describeit, d  use it to see a description
   help, h        Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --name value   a name to say (default: "bob")
   --help, -h     show help
   --version, -v  print the version

Example (BashComplete)

// set args for examples sake
os.Args = []string{"greet", "--generate-bash-completion"}

app := NewApp()
app.Name = "greet"
app.EnableBashCompletion = true
app.Commands = []Command{
	{
		Name:        "describeit",
		Aliases:     []string{"d"},
		Usage:       "use it to see a description",
		Description: "This is how we describe describeit the function",
		Action: func(c *Context) error {
			fmt.Printf("i like to describe things")
			return nil
		},
	}, {
		Name:        "next",
		Usage:       "next example",
		Description: "more stuff to see when generating bash completion",
		Action: func(c *Context) error {
			fmt.Printf("the next example")
			return nil
		},
	},
}

_ = app.Run(os.Args)

Output:

describeit
d
next
help
h

Example (BashComplete_withLongFlag)

os.Args = []string{"greet", "--s", "--generate-bash-completion"}

app := NewApp()
app.Name = "greet"
app.EnableBashCompletion = true
app.Flags = []Flag{
	IntFlag{
		Name: "other,o",
	},
	StringFlag{
		Name: "xyz,x",
	},
	StringFlag{
		Name: "some-flag,s",
	},
	StringFlag{
		Name: "similar-flag",
	},
}

_ = app.Run(os.Args)

Output:

--some-flag
--similar-flag

Example (BashComplete_withMultipleLongFlag)

os.Args = []string{"greet", "--st", "--generate-bash-completion"}

app := NewApp()
app.Name = "greet"
app.EnableBashCompletion = true
app.Flags = []Flag{
	IntFlag{
		Name: "int-flag,i",
	},
	StringFlag{
		Name: "string,s",
	},
	StringFlag{
		Name: "string-flag-2",
	},
	StringFlag{
		Name: "similar-flag",
	},
	StringFlag{
		Name: "some-flag",
	},
}

_ = app.Run(os.Args)

Output:

--string
--string-flag-2

Example (BashComplete_withShortFlag)

os.Args = []string{"greet", "-", "--generate-bash-completion"}

app := NewApp()
app.Name = "greet"
app.EnableBashCompletion = true
app.Flags = []Flag{
	IntFlag{
		Name: "other,o",
	},
	StringFlag{
		Name: "xyz,x",
	},
}

_ = app.Run(os.Args)

Output:

--other
-o
--xyz
-x
--help
-h
--version
-v

Example (CommandHelp)

// set args for examples sake
os.Args = []string{"greet", "h", "describeit"}

app := NewApp()
app.Name = "greet"
app.Flags = []Flag{
	StringFlag{Name: "name", Value: "bob", Usage: "a name to say"},
}
app.Commands = []Command{
	{
		Name:        "describeit",
		Aliases:     []string{"d"},
		Usage:       "use it to see a description",
		Description: "This is how we describe describeit the function",
		Action: func(c *Context) error {
			fmt.Printf("i like to describe things")
			return nil
		},
	},
}
_ = app.Run(os.Args)

Output:

NAME:
   greet describeit - use it to see a description

USAGE:
   greet describeit [arguments...]

DESCRIPTION:
   This is how we describe describeit the function

Example (NoAction)

app := App{}
app.Name = "greet"
_ = app.Run([]string{"greet"})

Output:

NAME:
   greet

USAGE:
    [global options] command [command options] [arguments...]

COMMANDS:
   help, h  Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --help, -h     show help
   --version, -v  print the version

Example (Subcommand)

// set args for examples sake
os.Args = []string{"say", "hi", "english", "--name", "Jeremy"}
app := NewApp()
app.Name = "say"
app.Commands = []Command{
	{
		Name:        "hello",
		Aliases:     []string{"hi"},
		Usage:       "use it to see a description",
		Description: "This is how we describe hello the function",
		Subcommands: []Command{
			{
				Name:        "english",
				Aliases:     []string{"en"},
				Usage:       "sends a greeting in english",
				Description: "greets someone in english",
				Flags: []Flag{
					StringFlag{
						Name:  "name",
						Value: "Bob",
						Usage: "Name of the person to greet",
					},
				},
				Action: func(c *Context) error {
					fmt.Println("Hello,", c.String("name"))
					return nil
				},
			},
		},
	},
}

_ = app.Run(os.Args)

Output:

Hello, Jeremy

Example (SubcommandNoAction)

app := App{}
app.Name = "greet"
app.Commands = []Command{
	{
		Name:        "describeit",
		Aliases:     []string{"d"},
		Usage:       "use it to see a description",
		Description: "This is how we describe describeit the function",
	},
}
_ = app.Run([]string{"greet", "describeit"})

Output:

NAME:
    describeit - use it to see a description

USAGE:
    describeit [arguments...]

DESCRIPTION:
   This is how we describe describeit the function

Example (ZshComplete)

// set args for examples sake
os.Args = []string{"greet", "--generate-bash-completion"}
_ = os.Setenv("_CLI_ZSH_AUTOCOMPLETE_HACK", "1")

app := NewApp()
app.Name = "greet"
app.EnableBashCompletion = true
app.Commands = []Command{
	{
		Name:        "describeit",
		Aliases:     []string{"d"},
		Usage:       "use it to see a description",
		Description: "This is how we describe describeit the function",
		Action: func(c *Context) error {
			fmt.Printf("i like to describe things")
			return nil
		},
	}, {
		Name:        "next",
		Usage:       "next example",
		Description: "more stuff to see when generating bash completion",
		Action: func(c *Context) error {
			fmt.Printf("the next example")
			return nil
		},
	},
}

_ = app.Run(os.Args)

Output:

describeit:use it to see a description
d:use it to see a description
next:next example
help:Shows a list of commands or help for one command
h:Shows a list of commands or help for one command

func (*App) RunAndExitOnError

func (a *App) RunAndExitOnError()

RunAndExitOnError calls .Run() and exits non-zero if an error was returned

Deprecated: instead you should return an error that fulfills cli.ExitCoder to cli.App.Run. This will cause the application to exit with the given eror code in the cli.ExitCoder

func (*App) RunAsSubcommand

func (a *App) RunAsSubcommand(ctx *Context) (err error)

RunAsSubcommand invokes the subcommand given the context, parses ctx.Args() to generate command-specific flags

func (*App) Setup

func (a *App) Setup()

Setup runs initialization code to ensure all data structures are ready for `Run` or inspection prior to `Run`. It is internally called by `Run`, but will return early if setup has already happened.

func (*App) ToFishCompletion

func (a *App) ToFishCompletion() (string, error)

ToFishCompletion creates a fish completion string for the `*App` The function errors if either parsing or writing of the string fails.

func (*App) ToMan

func (a *App) ToMan() (string, error)

ToMan creates a man page string for the `*App` The function errors if either parsing or writing of the string fails.

func (*App) ToMarkdown

func (a *App) ToMarkdown() (string, error)

ToMarkdown creates a markdown string for the `*App` The function errors if either parsing or writing of the string fails.

func (*App) VisibleCategories

func (a *App) VisibleCategories() []*CommandCategory

VisibleCategories returns a slice of categories and commands that are Hidden=false

func (*App) VisibleCommands

func (a *App) VisibleCommands() []Command

VisibleCommands returns a slice of the Commands with Hidden=false

func (*App) VisibleFlags

func (a *App) VisibleFlags() []Flag

VisibleFlags returns a slice of the Flags with Hidden=false

type Args

type Args []string

Args contains apps console arguments

func (Args) First

func (a Args) First() string

First returns the first argument, or else a blank string

func (Args) Get

func (a Args) Get(n int) string

Get returns the nth argument, or else a blank string

func (Args) Present

func (a Args) Present() bool

Present checks if there are any arguments present

func (Args) Swap

func (a Args) Swap(from, to int) error

Swap swaps arguments at the given indexes

func (Args) Tail

func (a Args) Tail() []string

Tail returns the rest of the arguments (not the first one) or else an empty string slice

type Author

type Author struct {
	Name  string // The Authors name
	Email string // The Authors email
}

Author represents someone who has contributed to a cli project.

func (Author) String

func (a Author) String() string

String makes Author comply to the Stringer interface, to allow an easy print in the templating process

type BashCompleteFunc

type BashCompleteFunc func(*Context)

BashCompleteFunc is an action to execute when the bash-completion flag is set

type BeforeFunc

type BeforeFunc func(*Context) error

BeforeFunc is an action to execute before any subcommands are run, but after the context is ready if a non-nil error is returned, no subcommands are run

type BoolFlag

type BoolFlag struct {
	Name        string
	Usage       string
	EnvVar      string
	FilePath    string
	Required    bool
	Hidden      bool
	Destination *bool
}

BoolFlag is a flag with type bool

func (BoolFlag) Apply

func (f BoolFlag) Apply(set *flag.FlagSet)

Apply populates the flag given the flag set and environment Ignores errors

func (BoolFlag) ApplyWithError

func (f BoolFlag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError populates the flag given the flag set and environment

func (BoolFlag) GetName

func (f BoolFlag) GetName() string

GetName returns the name of the flag

func (BoolFlag) GetUsage

func (f BoolFlag) GetUsage() string

GetUsage returns the usage string for the flag

func (BoolFlag) GetValue

func (f BoolFlag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (BoolFlag) IsRequired

func (f BoolFlag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (BoolFlag) String

func (f BoolFlag) String() string

String returns a readable representation of this value (for usage defaults)

func (BoolFlag) TakesValue

func (f BoolFlag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false

type BoolTFlag

type BoolTFlag struct {
	Name        string
	Usage       string
	EnvVar      string
	FilePath    string
	Required    bool
	Hidden      bool
	Destination *bool
}

BoolTFlag is a flag with type bool that is true by default

func (BoolTFlag) Apply

func (f BoolTFlag) Apply(set *flag.FlagSet)

Apply populates the flag given the flag set and environment Ignores errors

func (BoolTFlag) ApplyWithError

func (f BoolTFlag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError populates the flag given the flag set and environment

func (BoolTFlag) GetName

func (f BoolTFlag) GetName() string

GetName returns the name of the flag

func (BoolTFlag) GetUsage

func (f BoolTFlag) GetUsage() string

GetUsage returns the usage string for the flag

func (BoolTFlag) GetValue

func (f BoolTFlag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (BoolTFlag) IsRequired

func (f BoolTFlag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (BoolTFlag) String

func (f BoolTFlag) String() string

String returns a readable representation of this value (for usage defaults)

func (BoolTFlag) TakesValue

func (f BoolTFlag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false

type Command

type Command struct {
	// The name of the command
	Name string
	// short name of the command. Typically one character (deprecated, use `Aliases`)
	ShortName string
	// A list of aliases for the command
	Aliases []string
	// A short description of the usage of this command
	Usage string
	// Custom text to show on USAGE section of help
	UsageText string
	// A longer explanation of how the command works
	Description string
	// A short description of the arguments of this command
	ArgsUsage string
	// The category the command is part of
	Category string
	// The function to call when checking for bash command completions
	BashComplete BashCompleteFunc
	// An action to execute before any sub-subcommands are run, but after the context is ready
	// If a non-nil error is returned, no sub-subcommands are run
	Before BeforeFunc
	// An action to execute after any subcommands are run, but after the subcommand has finished
	// It is run even if Action() panics
	After AfterFunc
	// The function to call when this command is invoked
	Action interface{}

	// Execute this function if a usage error occurs.
	OnUsageError OnUsageErrorFunc
	// List of child commands
	Subcommands Commands
	// List of flags to parse
	Flags []Flag
	// Treat all flags as normal arguments if true
	SkipFlagParsing bool
	// Skip argument reordering which attempts to move flags before arguments,
	// but only works if all flags appear after all arguments. This behavior was
	// removed n version 2 since it only works under specific conditions so we
	// backport here by exposing it as an option for compatibility.
	SkipArgReorder bool
	// Boolean to hide built-in help command
	HideHelp bool
	// Boolean to hide this command from help or completion
	Hidden bool
	// Boolean to enable short-option handling so user can combine several
	// single-character bool arguments into one
	// i.e. foobar -o -v -> foobar -ov
	UseShortOptionHandling bool

	// Full name of command for help, defaults to full command name, including parent commands.
	HelpName string

	// CustomHelpTemplate the text template for the command help topic.
	// cli.go uses text/template to render templates. You can
	// render custom help text by setting this variable.
	CustomHelpTemplate string
	// contains filtered or unexported fields
}

Command is a subcommand for a cli.App.

func (Command) FullName

func (c Command) FullName() string

FullName returns the full name of the command. For subcommands this ensures that parent commands are part of the command path

func (Command) HasName

func (c Command) HasName(name string) bool

HasName returns true if Command.Name or Command.ShortName matches given name

func (Command) Names

func (c Command) Names() []string

Names returns the names including short names and aliases.

func (Command) Run

func (c Command) Run(ctx *Context) (err error)

Run invokes the command given the context, parses ctx.Args() to generate command-specific flags

func (Command) VisibleFlags

func (c Command) VisibleFlags() []Flag

VisibleFlags returns a slice of the Flags with Hidden=false

type CommandCategories

type CommandCategories []*CommandCategory

CommandCategories is a slice of *CommandCategory.

func (CommandCategories) AddCommand

func (c CommandCategories) AddCommand(category string, command Command) CommandCategories

AddCommand adds a command to a category.

func (CommandCategories) Len

func (c CommandCategories) Len() int

func (CommandCategories) Less

func (c CommandCategories) Less(i, j int) bool

func (CommandCategories) Swap

func (c CommandCategories) Swap(i, j int)

type CommandCategory

type CommandCategory struct {
	Name     string
	Commands Commands
}

CommandCategory is a category containing commands.

func (*CommandCategory) VisibleCommands

func (c *CommandCategory) VisibleCommands() []Command

VisibleCommands returns a slice of the Commands with Hidden=false

type CommandNotFoundFunc

type CommandNotFoundFunc func(*Context, string)

CommandNotFoundFunc is executed if the proper command cannot be found

type Commands

type Commands []Command

Commands is a slice of Command

type CommandsByName

type CommandsByName []Command

func (CommandsByName) Len

func (c CommandsByName) Len() int

func (CommandsByName) Less

func (c CommandsByName) Less(i, j int) bool

func (CommandsByName) Swap

func (c CommandsByName) Swap(i, j int)

type Context

type Context struct {
	App     *App
	Command Command
	// contains filtered or unexported fields
}

Context is a type that is passed through to each Handler action in a cli application. Context can be used to retrieve context-specific Args and parsed command-line options.

func NewContext

func NewContext(app *App, set *flag.FlagSet, parentCtx *Context) *Context

NewContext creates a new context. For use in when invoking an App or Command action.

func (*Context) Args

func (c *Context) Args() Args

Args returns the command line arguments associated with the context.

func (*Context) Bool

func (c *Context) Bool(name string) bool

Bool looks up the value of a local BoolFlag, returns false if not found

func (*Context) BoolT

func (c *Context) BoolT(name string) bool

BoolT looks up the value of a local BoolTFlag, returns false if not found

func (*Context) Duration

func (c *Context) Duration(name string) time.Duration

Duration looks up the value of a local DurationFlag, returns 0 if not found

func (*Context) FlagNames

func (c *Context) FlagNames() (names []string)

FlagNames returns a slice of flag names used in this context.

func (*Context) Float64

func (c *Context) Float64(name string) float64

Float64 looks up the value of a local Float64Flag, returns 0 if not found

func (*Context) Generic

func (c *Context) Generic(name string) interface{}

Generic looks up the value of a local GenericFlag, returns nil if not found

func (*Context) GlobalBool

func (c *Context) GlobalBool(name string) bool

GlobalBool looks up the value of a global BoolFlag, returns false if not found

func (*Context) GlobalBoolT

func (c *Context) GlobalBoolT(name string) bool

GlobalBoolT looks up the value of a global BoolTFlag, returns false if not found

func (*Context) GlobalDuration

func (c *Context) GlobalDuration(name string) time.Duration

GlobalDuration looks up the value of a global DurationFlag, returns 0 if not found

func (*Context) GlobalFlagNames

func (c *Context) GlobalFlagNames() (names []string)

GlobalFlagNames returns a slice of global flag names used by the app.

func (*Context) GlobalFloat64

func (c *Context) GlobalFloat64(name string) float64

GlobalFloat64 looks up the value of a global Float64Flag, returns 0 if not found

func (*Context) GlobalGeneric

func (c *Context) GlobalGeneric(name string) interface{}

GlobalGeneric looks up the value of a global GenericFlag, returns nil if not found

func (*Context) GlobalInt

func (c *Context) GlobalInt(name string) int

GlobalInt looks up the value of a global IntFlag, returns 0 if not found

func (*Context) GlobalInt64

func (c *Context) GlobalInt64(name string) int64

GlobalInt64 looks up the value of a global Int64Flag, returns 0 if not found

func (*Context) GlobalInt64Slice

func (c *Context) GlobalInt64Slice(name string) []int64

GlobalInt64Slice looks up the value of a global Int64SliceFlag, returns nil if not found

func (*Context) GlobalIntSlice

func (c *Context) GlobalIntSlice(name string) []int

GlobalIntSlice looks up the value of a global IntSliceFlag, returns nil if not found

func (*Context) GlobalIsSet

func (c *Context) GlobalIsSet(name string) bool

GlobalIsSet determines if the global flag was actually set

func (*Context) GlobalSet

func (c *Context) GlobalSet(name, value string) error

GlobalSet sets a context flag to a value on the global flagset

func (*Context) GlobalString

func (c *Context) GlobalString(name string) string

GlobalString looks up the value of a global StringFlag, returns "" if not found

func (*Context) GlobalStringSlice

func (c *Context) GlobalStringSlice(name string) []string

GlobalStringSlice looks up the value of a global StringSliceFlag, returns nil if not found

func (*Context) GlobalUint

func (c *Context) GlobalUint(name string) uint

GlobalUint looks up the value of a global UintFlag, returns 0 if not found

func (*Context) GlobalUint64

func (c *Context) GlobalUint64(name string) uint64

GlobalUint64 looks up the value of a global Uint64Flag, returns 0 if not found

func (*Context) Int

func (c *Context) Int(name string) int

Int looks up the value of a local IntFlag, returns 0 if not found

func (*Context) Int64

func (c *Context) Int64(name string) int64

Int64 looks up the value of a local Int64Flag, returns 0 if not found

func (*Context) Int64Slice

func (c *Context) Int64Slice(name string) []int64

Int64Slice looks up the value of a local Int64SliceFlag, returns nil if not found

func (*Context) IntSlice

func (c *Context) IntSlice(name string) []int

IntSlice looks up the value of a local IntSliceFlag, returns nil if not found

func (*Context) IsSet

func (c *Context) IsSet(name string) bool

IsSet determines if the flag was actually set

func (*Context) NArg

func (c *Context) NArg() int

NArg returns the number of the command line arguments.

func (*Context) NumFlags

func (c *Context) NumFlags() int

NumFlags returns the number of flags set

func (*Context) Parent

func (c *Context) Parent() *Context

Parent returns the parent context, if any

func (*Context) Set

func (c *Context) Set(name, value string) error

Set sets a context flag to a value.

func (*Context) String

func (c *Context) String(name string) string

String looks up the value of a local StringFlag, returns "" if not found

func (*Context) StringSlice

func (c *Context) StringSlice(name string) []string

StringSlice looks up the value of a local StringSliceFlag, returns nil if not found

func (*Context) Uint

func (c *Context) Uint(name string) uint

Uint looks up the value of a local UintFlag, returns 0 if not found

func (*Context) Uint64

func (c *Context) Uint64(name string) uint64

Uint64 looks up the value of a local Uint64Flag, returns 0 if not found

type DocGenerationFlag

type DocGenerationFlag interface {
	Flag

	// TakesValue returns true of the flag takes a value, otherwise false
	TakesValue() bool

	// GetUsage returns the usage string for the flag
	GetUsage() string

	// GetValue returns the flags value as string representation and an empty
	// string if the flag takes no value at all.
	GetValue() string
}

DocGenerationFlag is an interface that allows documentation generation for the flag

type DurationFlag

type DurationFlag struct {
	Name        string
	Usage       string
	EnvVar      string
	FilePath    string
	Required    bool
	Hidden      bool
	Value       time.Duration
	Destination *time.Duration
}

DurationFlag is a flag with type time.Duration (see https://golang.org/pkg/time/#ParseDuration)

func (DurationFlag) Apply

func (f DurationFlag) Apply(set *flag.FlagSet)

Apply populates the flag given the flag set and environment Ignores errors

func (DurationFlag) ApplyWithError

func (f DurationFlag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError populates the flag given the flag set and environment

func (DurationFlag) GetName

func (f DurationFlag) GetName() string

GetName returns the name of the flag

func (DurationFlag) GetUsage

func (f DurationFlag) GetUsage() string

GetUsage returns the usage string for the flag

func (DurationFlag) GetValue

func (f DurationFlag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (DurationFlag) IsRequired

func (f DurationFlag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (DurationFlag) String

func (f DurationFlag) String() string

String returns a readable representation of this value (for usage defaults)

func (DurationFlag) TakesValue

func (f DurationFlag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false

type ErrorFormatter

type ErrorFormatter interface {
	Format(s fmt.State, verb rune)
}

type ExitCoder

type ExitCoder interface {
	error
	ExitCode() int
}

ExitCoder is the interface checked by `App` and `Command` for a custom exit code

type ExitErrHandlerFunc

type ExitErrHandlerFunc func(context *Context, err error)

ExitErrHandlerFunc is executed if provided in order to handle ExitError values returned by Actions and Before/After functions.

type ExitError

type ExitError struct {
	// contains filtered or unexported fields
}

ExitError fulfills both the builtin `error` interface and `ExitCoder`

func NewExitError

func NewExitError(message interface{}, exitCode int) *ExitError

NewExitError makes a new *ExitError

func (*ExitError) Error

func (ee *ExitError) Error() string

Error returns the string message, fulfilling the interface required by `error`

func (*ExitError) ExitCode

func (ee *ExitError) ExitCode() int

ExitCode returns the exit code, fulfilling the interface required by `ExitCoder`

type Flag

type Flag interface {
	fmt.Stringer
	// Apply Flag settings to the given flag set
	Apply(*flag.FlagSet)
	GetName() string
}

Flag is a common interface related to parsing flags in cli. For more advanced flag parsing techniques, it is recommended that this interface be implemented.

var BashCompletionFlag Flag = BoolFlag{
	Name:   "generate-bash-completion",
	Hidden: true,
}

BashCompletionFlag enables bash-completion for all commands and subcommands

var HelpFlag Flag = BoolFlag{
	Name:  "help, h",
	Usage: "show help",
}

HelpFlag prints the help for all commands and subcommands Set to the zero value (BoolFlag{}) to disable flag -- keeps subcommand unless HideHelp is set to true)

var VersionFlag Flag = BoolFlag{
	Name:  "version, v",
	Usage: "print the version",
}

VersionFlag prints the version for the application

type FlagEnvHintFunc

type FlagEnvHintFunc func(envVar, str string) string

FlagEnvHintFunc is used by the default FlagStringFunc to annotate flag help with the environment variable details.

var FlagEnvHinter FlagEnvHintFunc = withEnvHint

FlagEnvHinter annotates flag help message with the environment variable details. This is used by the default FlagStringer.

type FlagFileHintFunc

type FlagFileHintFunc func(filePath, str string) string

FlagFileHintFunc is used by the default FlagStringFunc to annotate flag help with the file path details.

var FlagFileHinter FlagFileHintFunc = withFileHint

FlagFileHinter annotates flag help message with the environment variable details. This is used by the default FlagStringer.

type FlagNamePrefixFunc

type FlagNamePrefixFunc func(fullName, placeholder string) string

FlagNamePrefixFunc is used by the default FlagStringFunc to create prefix text for a flag's full name.

var FlagNamePrefixer FlagNamePrefixFunc = prefixedNames

FlagNamePrefixer converts a full flag name and its placeholder into the help message flag prefix. This is used by the default FlagStringer.

type FlagStringFunc

type FlagStringFunc func(Flag) string

FlagStringFunc is used by the help generation to display a flag, which is expected to be a single line.

var FlagStringer FlagStringFunc = stringifyFlag

FlagStringer converts a flag definition to a string. This is used by help to display a flag.

type FlagsByName

type FlagsByName []Flag

FlagsByName is a slice of Flag.

func (FlagsByName) Len

func (f FlagsByName) Len() int

func (FlagsByName) Less

func (f FlagsByName) Less(i, j int) bool

func (FlagsByName) Swap

func (f FlagsByName) Swap(i, j int)

type Float64Flag

type Float64Flag struct {
	Name        string
	Usage       string
	EnvVar      string
	FilePath    string
	Required    bool
	Hidden      bool
	Value       float64
	Destination *float64
}

Float64Flag is a flag with type float64

func (Float64Flag) Apply

func (f Float64Flag) Apply(set *flag.FlagSet)

Apply populates the flag given the flag set and environment Ignores errors

func (Float64Flag) ApplyWithError

func (f Float64Flag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError populates the flag given the flag set and environment

func (Float64Flag) GetName

func (f Float64Flag) GetName() string

GetName returns the name of the flag

func (Float64Flag) GetUsage

func (f Float64Flag) GetUsage() string

GetUsage returns the usage string for the flag

func (Float64Flag) GetValue

func (f Float64Flag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (Float64Flag) IsRequired

func (f Float64Flag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (Float64Flag) String

func (f Float64Flag) String() string

String returns a readable representation of this value (for usage defaults)

func (Float64Flag) TakesValue

func (f Float64Flag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false

type Generic

type Generic interface {
	Set(value string) error
	String() string
}

Generic is a generic parseable type identified by a specific flag

type GenericFlag

type GenericFlag struct {
	Name      string
	Usage     string
	EnvVar    string
	FilePath  string
	Required  bool
	Hidden    bool
	TakesFile bool
	Value     Generic
}

GenericFlag is a flag with type Generic

func (GenericFlag) Apply

func (f GenericFlag) Apply(set *flag.FlagSet)

Apply takes the flagset and calls Set on the generic flag with the value provided by the user for parsing by the flag Ignores parsing errors

func (GenericFlag) ApplyWithError

func (f GenericFlag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError takes the flagset and calls Set on the generic flag with the value provided by the user for parsing by the flag

func (GenericFlag) GetName

func (f GenericFlag) GetName() string

GetName returns the name of the flag

func (GenericFlag) GetUsage

func (f GenericFlag) GetUsage() string

GetUsage returns the usage string for the flag

func (GenericFlag) GetValue

func (f GenericFlag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (GenericFlag) IsRequired

func (f GenericFlag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (GenericFlag) String

func (f GenericFlag) String() string

String returns a readable representation of this value (for usage defaults)

func (GenericFlag) TakesValue

func (f GenericFlag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false

type Int64Flag

type Int64Flag struct {
	Name        string
	Usage       string
	EnvVar      string
	FilePath    string
	Required    bool
	Hidden      bool
	Value       int64
	Destination *int64
}

Int64Flag is a flag with type int64

func (Int64Flag) Apply

func (f Int64Flag) Apply(set *flag.FlagSet)

Apply populates the flag given the flag set and environment Ignores errors

func (Int64Flag) ApplyWithError

func (f Int64Flag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError populates the flag given the flag set and environment

func (Int64Flag) GetName

func (f Int64Flag) GetName() string

GetName returns the name of the flag

func (Int64Flag) GetUsage

func (f Int64Flag) GetUsage() string

GetUsage returns the usage string for the flag

func (Int64Flag) GetValue

func (f Int64Flag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (Int64Flag) IsRequired

func (f Int64Flag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (Int64Flag) String

func (f Int64Flag) String() string

String returns a readable representation of this value (for usage defaults)

func (Int64Flag) TakesValue

func (f Int64Flag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false

type Int64Slice

type Int64Slice []int64

Int64Slice is an opaque type for []int to satisfy flag.Value and flag.Getter

func (*Int64Slice) Get

func (f *Int64Slice) Get() interface{}

Get returns the slice of ints set by this flag

func (*Int64Slice) Set

func (f *Int64Slice) Set(value string) error

Set parses the value into an integer and appends it to the list of values

func (*Int64Slice) String

func (f *Int64Slice) String() string

String returns a readable representation of this value (for usage defaults)

func (*Int64Slice) Value

func (f *Int64Slice) Value() []int64

Value returns the slice of ints set by this flag

type Int64SliceFlag

type Int64SliceFlag struct {
	Name     string
	Usage    string
	EnvVar   string
	FilePath string
	Required bool
	Hidden   bool
	Value    *Int64Slice
}

Int64SliceFlag is a flag with type *Int64Slice

func (Int64SliceFlag) Apply

func (f Int64SliceFlag) Apply(set *flag.FlagSet)

Apply populates the flag given the flag set and environment Ignores errors

func (Int64SliceFlag) ApplyWithError

func (f Int64SliceFlag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError populates the flag given the flag set and environment

func (Int64SliceFlag) GetName

func (f Int64SliceFlag) GetName() string

GetName returns the name of the flag

func (Int64SliceFlag) GetUsage

func (f Int64SliceFlag) GetUsage() string

GetUsage returns the usage string for the flag

func (Int64SliceFlag) GetValue

func (f Int64SliceFlag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (Int64SliceFlag) IsRequired

func (f Int64SliceFlag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (Int64SliceFlag) String

func (f Int64SliceFlag) String() string

String returns a readable representation of this value (for usage defaults)

func (Int64SliceFlag) TakesValue

func (f Int64SliceFlag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false

type IntFlag

type IntFlag struct {
	Name        string
	Usage       string
	EnvVar      string
	FilePath    string
	Required    bool
	Hidden      bool
	Value       int
	Destination *int
}

IntFlag is a flag with type int

func (IntFlag) Apply

func (f IntFlag) Apply(set *flag.FlagSet)

Apply populates the flag given the flag set and environment Ignores errors

func (IntFlag) ApplyWithError

func (f IntFlag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError populates the flag given the flag set and environment

func (IntFlag) GetName

func (f IntFlag) GetName() string

GetName returns the name of the flag

func (IntFlag) GetUsage

func (f IntFlag) GetUsage() string

GetUsage returns the usage string for the flag

func (IntFlag) GetValue

func (f IntFlag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (IntFlag) IsRequired

func (f IntFlag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (IntFlag) String

func (f IntFlag) String() string

String returns a readable representation of this value (for usage defaults)

func (IntFlag) TakesValue

func (f IntFlag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false

type IntSlice

type IntSlice []int

IntSlice is an opaque type for []int to satisfy flag.Value and flag.Getter

func (*IntSlice) Get

func (f *IntSlice) Get() interface{}

Get returns the slice of ints set by this flag

func (*IntSlice) Set

func (f *IntSlice) Set(value string) error

Set parses the value into an integer and appends it to the list of values

func (*IntSlice) String

func (f *IntSlice) String() string

String returns a readable representation of this value (for usage defaults)

func (*IntSlice) Value

func (f *IntSlice) Value() []int

Value returns the slice of ints set by this flag

type IntSliceFlag

type IntSliceFlag struct {
	Name     string
	Usage    string
	EnvVar   string
	FilePath string
	Required bool
	Hidden   bool
	Value    *IntSlice
}

IntSliceFlag is a flag with type *IntSlice

func (IntSliceFlag) Apply

func (f IntSliceFlag) Apply(set *flag.FlagSet)

Apply populates the flag given the flag set and environment Ignores errors

func (IntSliceFlag) ApplyWithError

func (f IntSliceFlag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError populates the flag given the flag set and environment

func (IntSliceFlag) GetName

func (f IntSliceFlag) GetName() string

GetName returns the name of the flag

func (IntSliceFlag) GetUsage

func (f IntSliceFlag) GetUsage() string

GetUsage returns the usage string for the flag

func (IntSliceFlag) GetValue

func (f IntSliceFlag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (IntSliceFlag) IsRequired

func (f IntSliceFlag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (IntSliceFlag) String

func (f IntSliceFlag) String() string

String returns a readable representation of this value (for usage defaults)

func (IntSliceFlag) TakesValue

func (f IntSliceFlag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false

type MultiError

type MultiError struct {
	Errors []error
}

MultiError is an error that wraps multiple errors.

func NewMultiError

func NewMultiError(err ...error) MultiError

NewMultiError creates a new MultiError. Pass in one or more errors.

func (MultiError) Error

func (m MultiError) Error() string

Error implements the error interface.

type OnUsageErrorFunc

type OnUsageErrorFunc func(context *Context, err error, isSubcommand bool) error

OnUsageErrorFunc is executed if an usage error occurs. This is useful for displaying customized usage error messages. This function is able to replace the original error messages. If this function is not set, the "Incorrect usage" is displayed and the execution is interrupted.

type RequiredFlag

type RequiredFlag interface {
	Flag

	IsRequired() bool
}

RequiredFlag is an interface that allows us to mark flags as required it allows flags required flags to be backwards compatible with the Flag interface

type StringFlag

type StringFlag struct {
	Name        string
	Usage       string
	EnvVar      string
	FilePath    string
	Required    bool
	Hidden      bool
	TakesFile   bool
	Value       string
	Destination *string
}

StringFlag is a flag with type string

func (StringFlag) Apply

func (f StringFlag) Apply(set *flag.FlagSet)

Apply populates the flag given the flag set and environment Ignores errors

func (StringFlag) ApplyWithError

func (f StringFlag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError populates the flag given the flag set and environment

func (StringFlag) GetName

func (f StringFlag) GetName() string

GetName returns the name of the flag

func (StringFlag) GetUsage

func (f StringFlag) GetUsage() string

GetUsage returns the usage string for the flag

func (StringFlag) GetValue

func (f StringFlag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (StringFlag) IsRequired

func (f StringFlag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (StringFlag) String

func (f StringFlag) String() string

String returns a readable representation of this value (for usage defaults)

func (StringFlag) TakesValue

func (f StringFlag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false

type StringSlice

type StringSlice []string

StringSlice is an opaque type for []string to satisfy flag.Value and flag.Getter

func (*StringSlice) Get

func (f *StringSlice) Get() interface{}

Get returns the slice of strings set by this flag

func (*StringSlice) Set

func (f *StringSlice) Set(value string) error

Set appends the string value to the list of values

func (*StringSlice) String

func (f *StringSlice) String() string

String returns a readable representation of this value (for usage defaults)

func (*StringSlice) Value

func (f *StringSlice) Value() []string

Value returns the slice of strings set by this flag

type StringSliceFlag

type StringSliceFlag struct {
	Name      string
	Usage     string
	EnvVar    string
	FilePath  string
	Required  bool
	Hidden    bool
	TakesFile bool
	Value     *StringSlice
}

StringSliceFlag is a flag with type *StringSlice

func (StringSliceFlag) Apply

func (f StringSliceFlag) Apply(set *flag.FlagSet)

Apply populates the flag given the flag set and environment Ignores errors

func (StringSliceFlag) ApplyWithError

func (f StringSliceFlag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError populates the flag given the flag set and environment

func (StringSliceFlag) GetName

func (f StringSliceFlag) GetName() string

GetName returns the name of the flag

func (StringSliceFlag) GetUsage

func (f StringSliceFlag) GetUsage() string

GetUsage returns the usage string for the flag

func (StringSliceFlag) GetValue

func (f StringSliceFlag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (StringSliceFlag) IsRequired

func (f StringSliceFlag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (StringSliceFlag) String

func (f StringSliceFlag) String() string

String returns a readable representation of this value (for usage defaults)

func (StringSliceFlag) TakesValue

func (f StringSliceFlag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false

type Uint64Flag

type Uint64Flag struct {
	Name        string
	Usage       string
	EnvVar      string
	FilePath    string
	Required    bool
	Hidden      bool
	Value       uint64
	Destination *uint64
}

Uint64Flag is a flag with type uint64

func (Uint64Flag) Apply

func (f Uint64Flag) Apply(set *flag.FlagSet)

Apply populates the flag given the flag set and environment Ignores errors

func (Uint64Flag) ApplyWithError

func (f Uint64Flag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError populates the flag given the flag set and environment

func (Uint64Flag) GetName

func (f Uint64Flag) GetName() string

GetName returns the name of the flag

func (Uint64Flag) GetUsage

func (f Uint64Flag) GetUsage() string

GetUsage returns the usage string for the flag

func (Uint64Flag) GetValue

func (f Uint64Flag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (Uint64Flag) IsRequired

func (f Uint64Flag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (Uint64Flag) String

func (f Uint64Flag) String() string

String returns a readable representation of this value (for usage defaults)

func (Uint64Flag) TakesValue

func (f Uint64Flag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false

type UintFlag

type UintFlag struct {
	Name        string
	Usage       string
	EnvVar      string
	FilePath    string
	Required    bool
	Hidden      bool
	Value       uint
	Destination *uint
}

UintFlag is a flag with type uint

func (UintFlag) Apply

func (f UintFlag) Apply(set *flag.FlagSet)

Apply populates the flag given the flag set and environment Ignores errors

func (UintFlag) ApplyWithError

func (f UintFlag) ApplyWithError(set *flag.FlagSet) error

ApplyWithError populates the flag given the flag set and environment

func (UintFlag) GetName

func (f UintFlag) GetName() string

GetName returns the name of the flag

func (UintFlag) GetUsage

func (f UintFlag) GetUsage() string

GetUsage returns the usage string for the flag

func (UintFlag) GetValue

func (f UintFlag) GetValue() string

GetValue returns the flags value as string representation and an empty string if the flag takes no value at all.

func (UintFlag) IsRequired

func (f UintFlag) IsRequired() bool

IsRequired returns whether or not the flag is required

func (UintFlag) String

func (f UintFlag) String() string

String returns a readable representation of this value (for usage defaults)

func (UintFlag) TakesValue

func (f UintFlag) TakesValue() bool

TakesValue returns true of the flag takes a value, otherwise false