let stream = fs.createReadStream('a.txt')
stream.unshift(Buffer.from('添加内容'))

这样行不？

@xiedacon 谢谢，我先试一下

貌似不行的

@zhoujinhai 添加之后还需要写回文件吗？

var path = require('path');
var fs = require('mz/fs');
async function appendFileHeadAsync(filepath, head) {

 	if (!await fs.exists(filepath)) throw new Error("file not exist!!");
	
    var new_file_path = path.format({
        root: '/ignored',
        name: path.parse(filepath).name + "_n",
        ext: path.parse(filepath).ext
    });

    await fs.writeFile(new_file_path, Buffer.concat([
        Buffer.from(head, "utf8"),
        await fs.readFile(filepath, {
            "encoding": null
        })
    ]), {
        "encoding": "utf8",
        "flag": "w"
    });
    await fs.unlink(filepath);
    await fs.rename(new_file_path, filepath);

    return true;
}

appendFileHeadAsync(path.join(__dirname, 'a/test13333.txt'), "hello node js \r\n").then(a => {
	console.dir("success");
}).catch(err => {
    console.dir(err);
});

@xiedacon 嗯啊 是的

@godghdai 好的，谢谢！我先看一下

let stream = fs.createReadStream('a.txt')
stream.unshift(Buffer.from('添加内容'))
stream.pipe(fs.createWriteStream('b.txt'))

@zhoujinhai 这样写回去就行了 godghdai 那个好些，封装成方法了，有验证

@xiedacon 都可以 嘿嘿！谢谢啦