STDOUT是什么类型，我如何选择性地写入它？

# 将STDOUT重定向到output.txt文件
your_program > output.txt

# 将STDOUT追加到output.txt文件
your_program >> output.txt

import sys

def print_to_stdout(condition, message):
    if condition:
        sys.stdout.write(message + '\n')

# 使用示例
print_to_stdout(True, "This will be printed to STDOUT")
print_to_stdout(False, "This won't be printed")

import java.io.PrintStream;

public class SelectiveOutput {
    public static void main(String[] args) {
        PrintStream originalOut = System.out;
        PrintStream fileOut = null;
        try {
            fileOut = new PrintStream("output.txt");
            System.setOut(fileOut);

            // 这些输出将被重定向到output.txt文件
            System.out.println("This will be written to the file.");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (fileOut != null) {
                fileOut.close();
            }
            System.setOut(originalOut);
        }
    }
}

# 将STDOUT重定向到output.txt，将STDERR重定向到error.txt
your_program > output.txt 2> error.txt

import sys

sys.stdout.write("This is a standard output message.\n")
sys.stderr.write("This is a standard error message.\n")

System.out.println("This is a standard output message.");
System.err.println("This is a standard error message.");