Get terminal size in Go

You can use golang.org/x/term package (https://pkg.go.dev/golang.org/x/term)

Example

package main

import "golang.org/x/term"

func main() {
    if term.IsTerminal(0) {
        println("in a term")
    } else {
        println("not in a term")
    }
    width, height, err := term.GetSize(0)
    if err != nil {
        return
    }
    println("width:", width, "height:", height)
}

Output

in a term
width: 228 height: 27

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>

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.

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)
}