readline

Readline is A Pure Go Implementation of a libreadline-style Library.
The goal is to be a powerful alternater for GNU-Readline.

WHY: Readline will support most of features which GNU Readline is supported, and provide a pure go environment and a MIT license.

Demo

You can read the source code in example/main.go.

Todo

• Vim mode
• More funny examples

Usage

• Simplest example

import "github.com/chzyer/readline"

rl, err := readline.New("> ")
if err != nil {
	panic(err)
}
defer rl.Close()

for {
	line, err := rl.Readline()
	if err != nil { // io.EOF
		break
	}
	println(line)
}

• Example with durable history

rl, err := readline.NewEx(&readline.Config{
	Prompt: "> ",
	HistoryFile: "/tmp/readline.tmp",
})
if err != nil {
	panic(err)
}
defer rl.Close()

for {
	line, err := rl.Readline()
	if err != nil { // io.EOF
		break
	}
	println(line)
}

• Example with auto refresh

import (
	"log"
	"github.com/chzyer/readline"
)

rl, err := readline.New("> ")
if err != nil {
	panic(err)
}
defer rl.Close()
log.SetOutput(l.Stderr()) // let "log" write to l.Stderr instead of os.Stderr

go func() {
	for _ = range time.Tick(time.Second) {
		log.Println("hello")
	}
}()

for {
	line, err := rl.Readline()
	if err != nil { // io.EOF
		break
	}
	println(line)
}

• Example with auto completion

import (
	"log"
	"github.com/chzyer/readline"
)

var completer = readline.NewPrefixCompleter(
	readline.PcItem("say",
		readline.PcItem("hello"),
		readline.PcItem("bye"),
	),
	readline.PcItem("help"),
)

rl, err := readline.New(&readline.Config{
	Prompt:       "> ",
	AutoComplete: completer,
})
if err != nil {
	panic(err)
}
defer rl.Close()

for {
	line, err := rl.Readline()
	if err != nil { // io.EOF
		break
	}
	println(line)
}

Shortcut

Meta+B means press Esc and n separately.
Users can change that in terminal simulator(i.e. iTerm2) to Alt+B

• Shortcut in normal mode

Shortcut	Comment
Ctrl+A	Beginning of line
Ctrl+B / ←	Backward one character
Meta+B	Backward one word
Ctrl+C	Send io.EOF
Ctrl+D	Delete one character
Meta+D	Delete one word
Ctrl+E	End of line
Ctrl+F / →	Forward one character
Meta+F	Forward one word
Ctrl+G	Cancel
Ctrl+H	Delete previous character
Ctrl+I / Tab	Command line completion
Ctrl+J	Line feed
Ctrl+K	Cut text to the end of line
Ctrl+L	Clean screen (TODO)
Ctrl+M	Same as Enter key
Ctrl+N / ↓	Next line (in history)
Ctrl+P / ↑	Prev line (in history)
Ctrl+R	Search backwards in history
Ctrl+S	Search forwards in history
Ctrl+T	Transpose characters
Meta+T	Transpose words (TODO)
Ctrl+U	Cut text to the beginning of line
Ctrl+W	Cut previous word
Backspace	Delete previous character
Meta+Backspace	Cut previous word
Enter	Line feed

• Shortcut in Search Mode (Ctrl+S or Ctrl+r to enter this mode)

Shortcut	Comment
Ctrl+S	Search forwards in history
Ctrl+R	Search backwards in history
Ctrl+C / Ctrl+G	Exit Search Mode and revert the history
Backspace	Delete previous character
Other	Exit Search Mode

• Shortcut in Complete Select Mode (double Tab to enter this mode)

Shortcut	Comment
Ctrl+F	Move Forward
Ctrl+B	Move Backward
Ctrl+N	Move to next line
Ctrl+P	Move to previous line
Ctrl+A	Move to the first candicate in current line
Ctrl+E	Move to the last candicate in current line
Tab / Enter	Use the word on cursor to complete
Ctrl+C / Ctrl+G	Exit Complete Select Mode
Other	Exit Complete Select Mode

Tested with

Environment	$TERM
Mac OS X iTerm2	xterm
Mac OS X default Terminal.app	xterm
Mac OS X iTerm2 Screen	screen
Mac OS X iTerm2 Tmux	screen
Ubuntu Server 14.04 LTS	linux
Centos 7	linux
Windows 10	-

Notice:

• Ctrl+A is not working in screen because it used as a control command by default

If you test it otherwhere, whether it works fine or not, please let me know!

Feedback

If you have any question, please submit an GitHub Issues and any pull request is welcomed :)