Determine if Stdin has data with Go

Question

Is there a way to check if the input stream (os.Stdin) has data?

The post Read from initial stdin in GO? shows how to read the data, but unfortunately b

Answer 1

This seems to be reliable solution and works even with sleep/delayed data via pipe. https://coderwall.com/p/zyxyeg/golang-having-fun-with-os-stdin-and-shell-pipes

package main

import (
  "os"
  "fmt"
)

func main() {
  fi, err := os.Stdin.Stat()
  if err != nil {
    panic(err)
  }
  if fi.Mode() & os.ModeNamedPipe == 0 {
    fmt.Println("no pipe :(")
  } else {
    fmt.Println("hi pipe!")
  }
}

Answer 2

os.Stdin is like any other "file", so you can check it's size:

package main

import (
    "fmt"
    "os"
)

func main() {
    file := os.Stdin
    fi, err := file.Stat()
    if err != nil {
        fmt.Println("file.Stat()", err)
    }
    size := fi.Size()
    if size > 0 {
        fmt.Printf("%v bytes available in Stdin\n", size)
    } else {
        fmt.Println("Stdin is empty")
    }
}

I built this as a "pipe" executable, here is how it works:

$ ./pipe
Stdin is empty
$ echo test | ./pipe
5 bytes available in Stdin