Detecting Data Availability in Standard Input (Stdin) Using Go

In Go, the standard input stream (os.Stdin) can be checked for data using the technique of verifying its file size. Here's how it works:

The os.Stdin can be treated like any regular file, allowing us to examine its properties. To do this, we retrieve a FileInfo object using os.Stdin.Stat(). This object provides various information about the file, including its size.

By checking the file size, we can determine whether the Stdin stream contains data. If its size is greater than zero, it indicates the presence of data. Conversely, a size of zero indicates that Stdin is empty.

Below is a code example that demonstrates this method:

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")
    }
}

This technique provides an effective way to determine whether os.Stdin has data without blocking the program's execution while waiting for input. It can be particularly useful in cases where you need to dynamically handle incoming data from external sources or processes.