pty

README

pty

Pty is a Go package for using unix pseudo-terminals.

Install

go get github.com/creack/pty

Examples

Note that those examples are for demonstration purpose only, to showcase how to use the library. They are not meant to be used in any kind of production environment.

Command

package main

import (
	"io"
	"os"
	"os/exec"

	"github.com/creack/pty"
)

func main() {
	c := exec.Command("grep", "--color=auto", "bar")
	f, err := pty.Start(c)
	if err != nil {
		panic(err)
	}

	go func() {
		f.Write([]byte("foo\n"))
		f.Write([]byte("bar\n"))
		f.Write([]byte("baz\n"))
		f.Write([]byte{4}) // EOT
	}()
	io.Copy(os.Stdout, f)
}

Shell

package main

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

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

func test() error {
        // Create arbitrary command.
        c := exec.Command("bash")

        // 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 {
                        if err := pty.InheritSize(os.Stdin, ptmx); err != nil {
                                log.Printf("error resizing pty: %s", err)
                        }
                }
        }()
        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() {
        if err := test(); err != nil {
                log.Fatal(err)
        }
}

Documentation

Overview

Package pty provides functions for working with Unix terminals.

Index

• Constants
• Variables
• func Getsize(t *os.File) (rows, cols int, err error)
• func InheritSize(pty, tty *os.File) error
• func Open() (pty, tty *os.File, err error)
• func Setsize(t *os.File, ws *Winsize) error
• func Start(cmd *exec.Cmd) (*os.File, error)
• func StartWithAttrs(c *exec.Cmd, sz *Winsize, attrs *syscall.SysProcAttr) (*os.File, error)
• func StartWithSize(cmd *exec.Cmd, ws *Winsize) (*os.File, error)
• type Winsize
  • func GetsizeFull(t *os.File) (size *Winsize, err error)

Constants

const (
	TIOCGWINSZ = syscall.TIOCGWINSZ
	TIOCSWINSZ = syscall.TIOCSWINSZ
)

Variables

var ErrUnsupported = errors.New("unsupported")

ErrUnsupported is returned if a function is not available on the current platform.

Functions

func Getsize

func Getsize(t *os.File) (rows, cols int, err error)

Getsize returns the number of rows (lines) and cols (positions in each line) in terminal t.

func InheritSize

func InheritSize(pty, tty *os.File) error

InheritSize applies the terminal size of pty to tty. This should be run in a signal handler for syscall.SIGWINCH to automatically resize the tty when the pty receives a window size change notification.

func Open

func Open() (pty, tty *os.File, err error)

Open a pty and its corresponding tty.

func Setsize

func Setsize(t *os.File, ws *Winsize) error

Setsize resizes t to s.

func Start

func Start(cmd *exec.Cmd) (*os.File, error)

Start assigns a pseudo-terminal tty os.File to c.Stdin, c.Stdout, and c.Stderr, calls c.Start, and returns the File of the tty's corresponding pty.

Starts the process in a new session and sets the controlling terminal.

func StartWithAttrs

func StartWithAttrs(c *exec.Cmd, sz *Winsize, attrs *syscall.SysProcAttr) (*os.File, error)

StartWithAttrs assigns a pseudo-terminal tty os.File to c.Stdin, c.Stdout, and c.Stderr, calls c.Start, and returns the File of the tty's corresponding pty.

This will resize the pty to the specified size before starting the command if a size is provided. The `attrs` parameter overrides the one set in c.SysProcAttr.

This should generally not be needed. Used in some edge cases where it is needed to create a pty without a controlling terminal.

func StartWithSize

func StartWithSize(cmd *exec.Cmd, ws *Winsize) (*os.File, error)

StartWithSize assigns a pseudo-terminal tty os.File to c.Stdin, c.Stdout, and c.Stderr, calls c.Start, and returns the File of the tty's corresponding pty.

This will resize the pty to the specified size before starting the command. Starts the process in a new session and sets the controlling terminal.

Types

type Winsize

type Winsize struct {
	Rows uint16 // ws_row: Number of rows (in cells)
	Cols uint16 // ws_col: Number of columns (in cells)
	X    uint16 // ws_xpixel: Width in pixels
	Y    uint16 // ws_ypixel: Height in pixels
}

Winsize describes the terminal size.

func GetsizeFull

func GetsizeFull(t *os.File) (size *Winsize, err error)

GetsizeFull returns the full terminal size description.