Get terminal size in Go

问题:

How to get tty size with Go lang? I am trying do this with executing stty size command, but i can't craft code right.

package main

import (
  "os/exec"
  "fmt"
  "log"
)

func main() {
  out, err := exec.Command("stty", "size").Output()
  fmt.Printf("out: %#v\n", out)
  fmt.Printf("err: %#v\n", err)
  if err != nil {
    log.Fatal(err)
  }
}

Output:

out: []byte{}
err: &exec.ExitError{ProcessState:(*os.ProcessState)(0xc200066520)}
2013/05/16 02:35:57 exit status 1
exit status 1

I think this is because Go spawns a process not related to the current tty, with which it is working. How can I relate the command to current terminal in order to get its size?

回答1:

It works if you give the child process access to the parent's stdin:

package main

import (
  "os/exec"
  "fmt"
  "log"
  "os"
)

func main() {
  cmd := exec.Command("stty", "size")
  cmd.Stdin = os.Stdin
  out, err := cmd.Output()
  fmt.Printf("out: %#v\n", string(out))
  fmt.Printf("err: %#v\n", err)
  if err != nil {
    log.Fatal(err)
  }
}

Yields:

out: "36 118\n"
err: <nil>

回答2:

I was stuck on a similar problem. Here is what I ended up with.

It doesn't use a subprocess, so might be desirable in some situations.

import (
    "syscall"
    "unsafe"
)

type winsize struct {
    Row    uint16
    Col    uint16
    Xpixel uint16
    Ypixel uint16
}

func getWidth() uint {
    ws := &winsize{}
    retCode, _, errno := syscall.Syscall(syscall.SYS_IOCTL,
        uintptr(syscall.Stdin),
        uintptr(syscall.TIOCGWINSZ),
        uintptr(unsafe.Pointer(ws)))

    if int(retCode) == -1 {
        panic(errno)
    }
    return uint(ws.Col)
}

回答3:

I just wanted to add a new answer since I ran into this problem recently. There is a terminal package which lives inside the official ssh package https://godoc.org/golang.org/x/crypto/ssh/terminal.

This package provides a method to easily get the size of a terminal.

width, height, err := terminal.GetSize(0)

0 would be the file descriptor of the terminal you want the size of. To get the fd or you current terminal you can always do int(os.Stdin.Fd())

Under the covers it uses a syscall to get the terminal size for the given fd.

回答4:

If anyone's interested I made a package to make this easier.

https://github.com/wayneashleyberry/terminal-dimensions

package main

import (
    "fmt"

    terminal "github.com/wayneashleyberry/terminal-dimensions"
)

func main() {
    x, _ := terminal.Width()
    y, _ := terminal.Height()
    fmt.Printf("Terminal is %d wide and %d high", x, y)
}