ishell

ishell is an interactive shell library for creating interactive cli applications.

Usage

import "strings"
import "github.com/abiosoft/ishell/v2"

func main(){
    // create new shell.
    // by default, new shell includes 'exit', 'help' and 'clear' commands.
    shell := ishell.New()

    // display welcome info.
    shell.Println("Sample Interactive Shell")

    // register a function for "greet" command.
    shell.AddCmd(&ishell.Cmd{
        Name: "greet",
        Help: "greet user",
        Func: func(c *ishell.Context) {
            c.Println("Hello", strings.Join(c.Args, " "))
        },
    })

    // run shell
    shell.Run()
}

Execution

Sample Interactive Shell
>>> help

Commands:
  clear      clear the screen
  greet      greet user
  exit       exit the program
  help       display help

>>> greet Someone Somewhere
Hello Someone Somewhere
>>> exit
$

Reading input

// simulate an authentication
shell.AddCmd(&ishell.Cmd{
    Name: "login",
    Help: "simulate a login",
    Func: func(c *ishell.Context) {
        // disable the '>>>' for cleaner same line input.
        c.ShowPrompt(false)
        defer c.ShowPrompt(true) // yes, revert after login.

        // get username
        c.Print("Username: ")
        username := c.ReadLine()

        // get password.
        c.Print("Password: ")
        password := c.ReadPassword()

        ... // do something with username and password

        c.Println("Authentication Successful.")
    },
})

Execution

>>> login
Username: someusername
Password:
Authentication Successful.

Multiline input

Builtin support for multiple lines.

>>> This is \
... multi line

>>> Cool that << EOF
... everything here goes
... as a single argument.
... EOF

User defined

shell.AddCmd(&ishell.Cmd{
    Name: "multi",
    Help: "input in multiple lines",
    Func: func(c *ishell.Context) {
        c.Println("Input multiple lines and end with semicolon ';'.")
        lines := c.ReadMultiLines(";")
        c.Println("Done reading. You wrote:")
        c.Println(lines)
    },
})

Execution

>>> multi
Input multiple lines and end with semicolon ';'.
>>> this is user defined
... multiline input;
You wrote:
this is user defined
multiline input;

Keyboard interrupt

Builtin interrupt handler.

>>> ^C
Input Ctrl-C once more to exit
>>> ^C
Interrupted
exit status 1

Custom

shell.Interrupt(func(count int, c *ishell.Context) { ... })

Multiple Choice

func(c *ishell.Context) {
    choice := c.MultiChoice([]string{
        "Golangers",
        "Go programmers",
        "Gophers",
        "Goers",
    }, "What are Go programmers called ?")
    if choice == 2 {
        c.Println("You got it!")
    } else {
        c.Println("Sorry, you're wrong.")
    }
},

Output

What are Go programmers called ?
  Golangers
  Go programmers
> Gophers
  Goers

You got it!

Checklist

func(c *ishell.Context) {
    languages := []string{"Python", "Go", "Haskell", "Rust"}
    choices := c.Checklist(languages,
        "What are your favourite programming languages ?", nil)
    out := func() []string { ... } // convert index to language
    c.Println("Your choices are", strings.Join(out(), ", "))
}

Output

What are your favourite programming languages ?
    Python
  ✓ Go
    Haskell
 >✓ Rust

Your choices are Go, Rust

Progress Bar

Determinate

func(c *ishell.Context) {
    c.ProgressBar().Start()
    for i := 0; i < 101; i++ {
        c.ProgressBar().Suffix(fmt.Sprint(" ", i, "%"))
        c.ProgressBar().Progress(i)
        ... // some background computation
    }
    c.ProgressBar().Stop()
}

Output

[==========>         ] 50%

Indeterminate

func(c *ishell.Context) {
    c.ProgressBar().Indeterminate(true)
    c.ProgressBar().Start()
    ... // some background computation
    c.ProgressBar().Stop()
}

Output

[ ====               ]

Custom display using briandowns/spinner.

display := ishell.ProgressDisplayCharSet(spinner.CharSets[11])
func(c *Context) { c.ProgressBar().Display(display) ... }

// or set it globally
ishell.ProgressBar().Display(display)

Durable history

// Read and write history to $HOME/.ishell_history
shell.SetHomeHistoryPath(".ishell_history")

Non-interactive execution

In some situations it is desired to exit the program directly after executing a single command.

// when started with "exit" as first argument, assume non-interactive execution
if len(os.Args) > 1 && os.Args[1] == "exit" {
    shell.Process(os.Args[2:]...)
} else {
    // start shell
    shell.Run()
}

# Run normally - interactive mode:
$ go run main.go
>>> |

# Run non-interactivelly
$ go run main.go exit greet Someusername
Hello Someusername

Output with Color

You can use fatih/color.

func(c *ishell.Context) {
    yellow := color.New(color.FgYellow).SprintFunc()
    c.Println(yellow("This line is yellow"))
}

Execution

>>> color
This line is yellow

Example

Available here.

go run example/main.go

Supported Platforms

• Linux
• OSX
• Windows [Not tested but should work]

Note

ishell is in active development and can still change significantly.

Roadmap (in no particular order)

• Multiline inputs
• Command history
• Customizable tab completion
• Handle ^C interrupts
• Subcommands and help texts
• Scrollable paged output
• Progress bar
• Multiple choice prompt
• Checklist prompt
• Support for command aliases
• Multiple line progress bars
• Testing, testing, testing

Contribution

1. Create an issue to discuss it.
2. Send in Pull Request.

License

MIT

Credits

Library	Use
github.com/flynn-archive/go-shlex	splitting input into command and args.
github.com/chzyer/readline	readline capabilities.

Donate

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paypal: a@abiosoft.com