将文件的最后几行添加到文件的开头

with open('file.txt', 'r+') as file:
    lines = file.readlines()
    file.seek(0)
    file.write(''.join(lines[-3:]))
    file.seek(0, 2)
    file.truncate()

import java.io.*;

public class FileManipulation {
    public static void main(String[] args) {
        try {
            File file = new File("file.txt");
            BufferedReader reader = new BufferedReader(new FileReader(file));
            String line;
            StringBuilder content = new StringBuilder();
            while ((line = reader.readLine()) != null) {
                content.append(line).append("\n");
            }
            reader.close();

            int lastLinesToKeep = 3;
            String[] lines = content.toString().split("\n");
            StringBuilder newContent = new StringBuilder();
            for (int i = Math.max(lines.length - lastLinesToKeep, 0); i < lines.length; i++) {
                newContent.append(lines[i]).append("\n");
            }
            newContent.append(content);

            FileWriter writer = new FileWriter(file);
            writer.write(newContent.toString());
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

const fs = require('fs');

fs.readFile('file.txt', 'utf8', function (err, data) {
    if (err) {
        console.error(err);
        return;
    }

    const lines = data.split('\n');
    const lastLines = lines.slice(-3);
    const newContent = lastLines.join('\n') + '\n' + data;

    fs.writeFile('file.txt', newContent, function (err) {
        if (err) {
            console.error(err);
            return;
        }
        console.log('File modified successfully.');
    });
});