#include <unistd.h>
#include <stdio.h>

int main() {
    if (isatty(fileno(stdin))) {
        printf("stdin is from terminal (not redirected)\n");
    } else {
        printf("stdin is redirected (from pipe/file)\n");
    }
    return 0;
}

import sys

if sys.stdin.isatty():
    print("stdin is from terminal (not redirected)")
else:
    print("stdin is redirected (from pipe/file)")

import java.io.Console;

public class StdinCheck {
    public static void main(String[] args) {
        Console console = System.console();
        if (console != null) {
            System.out.println("stdin is from terminal (not redirected)");
        } else {
            System.out.println("stdin is redirected (from pipe/file)");
        }
    }
}

package main

import (
    "os"
    "log"
)

func main() {
    fileInfo, _ := os.Stdin.Stat()
    if (fileInfo.Mode() & os.ModeCharDevice) == os.ModeCharDevice {
        log.Println("stdin is from terminal (not redirected)")
    } else {
        log.Println("stdin is redirected (from pipe/file)")
    }
}

if [ -t 0 ]; then
    echo "stdin is from terminal (not redirected)"
else
    echo "stdin is redirected (from pipe/file)"
fi