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) { println("Greetings") } app.Run(os.Args) }
Index ¶
- Variables
- func DefaultAppComplete(c *Context)
- func ShowAppHelp(c *Context)
- func ShowCommandCompletions(ctx *Context, command string)
- func ShowCommandHelp(ctx *Context, command string)
- func ShowCompletions(c *Context)
- func ShowSubcommandHelp(c *Context)
- func ShowVersion(c *Context)
- type App
- type Args
- type Author
- type BoolFlag
- type BoolTFlag
- type Command
- type 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) GlobalDuration(name string) time.Duration
- func (c *Context) GlobalFlagNames() (names []string)
- func (c *Context) GlobalGeneric(name string) interface{}
- func (c *Context) GlobalInt(name string) int
- func (c *Context) GlobalIntSlice(name string) []int
- func (c *Context) GlobalIsSet(name string) bool
- func (c *Context) GlobalString(name string) string
- func (c *Context) GlobalStringSlice(name string) []string
- func (c *Context) Int(name string) int
- func (c *Context) IntSlice(name string) []int
- func (c *Context) IsSet(name string) bool
- func (c *Context) NumFlags() int
- func (c *Context) Parent() *Context
- func (c *Context) String(name string) string
- func (c *Context) StringSlice(name string) []string
- type DurationFlag
- type Flag
- type Float64Flag
- type Generic
- type GenericFlag
- type IntFlag
- type IntSlice
- type IntSliceFlag
- type MultiError
- type StringFlag
- type StringSlice
- type StringSliceFlag
Examples ¶
Constants ¶
This section is empty.
Variables ¶
var AppHelpTemplate = `` /* 573-byte string literal not displayed */
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 BashCompletionFlag = BoolFlag{
Name: "generate-bash-completion",
}
This flag enables bash-completion for all commands and subcommands
var CommandHelpTemplate = `` /* 288-byte string literal not displayed */
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 HelpFlag = BoolFlag{
Name: "help, h",
Usage: "show help",
}
This flag 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 HelpPrinter helpPrinter = printHelp
var SubcommandHelpTemplate = `` /* 318-byte string literal not displayed */
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 VersionFlag = BoolFlag{
Name: "version, v",
Usage: "print the version",
}
This flag prints the version for the application
var VersionPrinter = printVersion
Prints version for the App
Functions ¶
func DefaultAppComplete ¶
func DefaultAppComplete(c *Context)
Prints the list of subcommands as the default app completion method
func ShowAppHelp ¶
func ShowAppHelp(c *Context)
func ShowCommandCompletions ¶
Prints the custom completions for a given command
func ShowCommandHelp ¶
Prints help for the given command
func ShowCompletions ¶
func ShowCompletions(c *Context)
Prints the lists of commands within a given context
Types ¶
type App ¶
type App struct { // The name of the program. Defaults to os.Args[0] Name string // Full name of command for help, defaults to Name HelpName string // Description of the program. Usage string // Description of the program argument format. ArgsUsage string // Version of the program Version 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 HideVersion bool // An action to execute when the bash-completion flag is set BashComplete func(context *Context) // 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 func(context *Context) error // An action to execute after any subcommands are run, but after the subcommand has finished // It is run even if Action() panics After func(context *Context) error // The action to execute when no subcommands are specified Action func(context *Context) // Execute this function if the proper command cannot be found CommandNotFound func(context *Context, command string) // 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 }
App is the main structure of a cli application. It is recomended that an app be created with the cli.NewApp() function
func NewApp ¶
func NewApp() *App
Creates a new cli Application with some reasonable defaults for Name, Usage, Version and Action.
func (*App) Run ¶
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) { fmt.Printf("Hello %v\n", c.String("name")) } app.Author = "Harrison" app.Email = "harrison@lolwut.com" app.Authors = []Author{Author{Name: "Oliver Allen", Email: "oliver@toyshop.com"}} app.Run(os.Args)
Output: Hello Jeremy
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) { fmt.Printf("i like to describe things") }, }, { Name: "next", Usage: "next example", Description: "more stuff to see when generating bash completion", Action: func(c *Context) { fmt.Printf("the next example") }, }, } app.Run(os.Args)
Output: describeit d next help h
Example (Help) ¶
// 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) { fmt.Printf("i like to describe things") }, }, } 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 (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) { fmt.Println("Hello,", c.String("name")) }, }, }, }, } app.Run(os.Args)
Output: Hello, Jeremy
func (*App) RunAndExitOnError ¶
func (a *App) RunAndExitOnError()
Another entry point to the cli app, takes care of passing arguments and error handling
func (*App) RunAsSubcommand ¶
Invokes the subcommand given the context, parses ctx.Args() to generate command-specific flags
type BoolFlag ¶
BoolFlag is a switch that defaults to false
type BoolTFlag ¶
BoolTFlag this represents a boolean flag that is true by default, but can still be set to false by --some-flag=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 // A longer explanation of how the command works Description string // A short description of the arguments of this command ArgsUsage string // The function to call when checking for bash command completions BashComplete func(context *Context) // 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 func(context *Context) error // An action to execute after any subcommands are run, but after the subcommand has finished // It is run even if Action() panics After func(context *Context) error // The function to call when this command is invoked Action func(context *Context) // List of child commands Subcommands []Command // List of flags to parse Flags []Flag // Treat all flags as normal arguments if true SkipFlagParsing bool // Boolean to hide built-in help command HideHelp bool // Full name of command for help, defaults to full command name, including parent commands. HelpName string // contains filtered or unexported fields }
Command is a subcommand for a cli.App.
func (Command) FullName ¶
Returns the full name of the command. For subcommands this ensures that parent commands are part of the command path
type Context ¶
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 ¶
Creates a new context. For use in when invoking an App or Command action.
func (*Context) Bool ¶
Looks up the value of a local bool flag, returns false if no bool flag exists
func (*Context) BoolT ¶
Looks up the value of a local boolT flag, returns false if no bool flag exists
func (*Context) Duration ¶
Looks up the value of a local time.Duration flag, returns 0 if no time.Duration flag exists
func (*Context) Float64 ¶
Looks up the value of a local float64 flag, returns 0 if no float64 flag exists
func (*Context) Generic ¶
Looks up the value of a local generic flag, returns nil if no generic flag exists
func (*Context) GlobalBool ¶
Looks up the value of a global bool flag, returns false if no bool flag exists
func (*Context) GlobalDuration ¶
Looks up the value of a global time.Duration flag, returns 0 if no time.Duration flag exists
func (*Context) GlobalFlagNames ¶
Returns a slice of global flag names used by the app.
func (*Context) GlobalGeneric ¶
Looks up the value of a global generic flag, returns nil if no generic flag exists
func (*Context) GlobalInt ¶
Looks up the value of a global int flag, returns 0 if no int flag exists
func (*Context) GlobalIntSlice ¶
Looks up the value of a global int slice flag, returns nil if no int slice flag exists
func (*Context) GlobalIsSet ¶
Determines if the global flag was actually set
func (*Context) GlobalString ¶
Looks up the value of a global string flag, returns "" if no string flag exists
func (*Context) GlobalStringSlice ¶
Looks up the value of a global string slice flag, returns nil if no string slice flag exists
func (*Context) IntSlice ¶
Looks up the value of a local int slice flag, returns nil if no int slice flag exists
func (*Context) String ¶
Looks up the value of a local string flag, returns "" if no string flag exists
func (*Context) StringSlice ¶
Looks up the value of a local string slice flag, returns nil if no string slice flag exists
type DurationFlag ¶
type DurationFlag struct { Name string Value time.Duration Usage string EnvVar string Destination *time.Duration }
DurationFlag is a flag that takes a duration specified in Go's duration format: 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
func (DurationFlag) String ¶
func (f DurationFlag) String() string
String returns a readable representation of this value (for usage defaults)
type Flag ¶
type Flag interface { fmt.Stringer // Apply Flag settings to the given flag set Apply(*flag.FlagSet) // contains filtered or unexported methods }
Flag is a common interface related to parsing flags in cli. For more advanced flag parsing techniques, it is recomended that this interface be implemented.
type Float64Flag ¶
type Float64Flag struct { Name string Value float64 Usage string EnvVar string Destination *float64 }
Float64Flag is a flag that takes an float value Errors if the value provided cannot be parsed
func (Float64Flag) Apply ¶
func (f Float64Flag) Apply(set *flag.FlagSet)
Apply populates the flag given the flag set and environment
type GenericFlag ¶
GenericFlag is the flag type for types implementing 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
func (GenericFlag) String ¶
func (f GenericFlag) String() string
String returns the string representation of the generic flag to display the help text to the user (uses the String() method of the generic flag to show the value)
type IntFlag ¶
IntFlag is a flag that takes an integer Errors if the value provided cannot be parsed
type IntSlice ¶
type IntSlice []int
StringSlice is an opaque type for []int to satisfy flag.Value
type IntSliceFlag ¶
IntSliceFlag is an int flag that can be specified multiple times on the command-line
func (IntSliceFlag) Apply ¶
func (f IntSliceFlag) Apply(set *flag.FlagSet)
Apply populates the flag given the flag set and environment
type MultiError ¶
type MultiError struct {
Errors []error
}
func NewMultiError ¶
func NewMultiError(err ...error) MultiError
func (MultiError) Error ¶
func (m MultiError) Error() string
type StringFlag ¶
StringFlag represents a flag that takes as string value
func (StringFlag) Apply ¶
func (f StringFlag) Apply(set *flag.FlagSet)
Apply populates the flag given the flag set and environment
type StringSlice ¶
type StringSlice []string
StringSlice is an opaque type for []string to satisfy flag.Value
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 Value *StringSlice Usage string EnvVar string }
StringSlice is a string flag that can be specified multiple times on the command-line
func (StringSliceFlag) Apply ¶
func (f StringSliceFlag) Apply(set *flag.FlagSet)
Apply populates the flag given the flag set and environment