A terminal emulator in Go

README.md

A terminal-based terminal emulator

Run a terminal from inside your terminal.

The purpose of this code is to demonstrate how to have applications running in a PTY (psedoterminal) environment.

Usage

Be sure to have Go installed.

Then just:

go run . /bin/bash

go.mod

module gist.github.com/shovon/8307ba2559f23baa249601cf8af900c7

go 1.22.4

require (
	github.com/creack/pty v1.1.21
	golang.org/x/sys v0.22.0
	golang.org/x/term v0.22.0
)

go.sum

github.com/creack/pty v1.1.21 h1:1/QdRyBaHHJP61QkWMXlOIBfsgdDeeKfK8SYVUWJKf0=
github.com/creack/pty v1.1.21/go.mod h1:MOBLtS5ELjhRRrroQr9kyvTxUAFNvYEK993ew/Vr4O4=
golang.org/x/sys v0.22.0 h1:RI27ohtqKCnwULzJLqkv897zojh5/DwS/ENaMzUOaWI=
golang.org/x/sys v0.22.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
golang.org/x/term v0.22.0 h1:BbsgPEJULsl2fV/AT3v15Mjva5yXKQDyKf+TbDz7QJk=
golang.org/x/term v0.22.0/go.mod h1:F3qCibpT5AMpCRfhfT53vVJwhLtIVHhB9XDjfFvnMI4=

main.go

package main

import (
	"io"
	"log"
	"os"
	"os/exec"
	"os/signal"
	"syscall"

	"github.com/creack/pty"
	"golang.org/x/term"
)

func runTerminal(c *exec.Cmd) error {

	// Start the command with a pty.
	ptmx, err := pty.Start(c)
	if err != nil {
		return err
	}
	// Make sure to close the pty at the end.
	defer func() { _ = ptmx.Close() }() // Best effort.

	// Handle pty size.
	ch := make(chan os.Signal, 1)
	signal.Notify(ch, syscall.SIGWINCH)
	go func() {
		for range ch {
			pty.InheritSize(os.Stdin, ptmx)
		}
	}()
	ch <- syscall.SIGWINCH                        // Initial resize.
	defer func() { signal.Stop(ch); close(ch) }() // Cleanup signals when done.

	// Set stdin in raw mode.
	oldState, err := term.MakeRaw(int(os.Stdin.Fd()))
	if err != nil {
		panic(err)
	}
	defer func() { _ = term.Restore(int(os.Stdin.Fd()), oldState) }() // Best effort.

	// Copy stdin to the pty and the pty to stdout.
	// NOTE: The goroutine will keep reading until the next keystroke before returning.
	go func() { _, _ = io.Copy(ptmx, os.Stdin) }()
	_, _ = io.Copy(os.Stdout, ptmx)

	return nil
}

func main() {
	// Create arbitrary command.
	c := exec.Command(os.Args[1], os.Args[2:]...)

	if err := runTerminal(c); err != nil {
		log.Fatal(err)
	}
}