fs 完成写入文件后如何运行命令？

Question

Here is the code in question:

        const scriptFiles = fs.readdirSync(scriptsPath)
            .filter(file => file.endsWith(".sql"));

        for (const file of scriptFiles) {

            var data = fs.readFileSync(`${scriptsPath}/${file}`, 'utf8');
            fs.appendFile(`${scriptsPath}/Hotfix.sql`, data.toString() + "\n", (err) => {
                if (err) throw new Error(err)
                console.log('Appending ' + file + '...')
            })

            process.stdout.cursorTo(0);
        }

        console.log(`start ${scriptsPath}/Hotfix.sql`)
        exec(`start ${scriptsPath}/Hotfix.sql`)

The problem that I'm running into is that it is attempting to open/start scriptsPath/Hotfix.sql before anything has been appended to the file. For example, here is the output from the console.log()s I've added to the script:

start scriptsPath/Hotfix.sql
Appending file1.sql...    
Appending file2.sql...

is there a way I can have the script wait until the for loop has completed before attempting to execute the command?

Answer 1

Either use .appendFileSync() and remove the (err)=> callback, or write your code as async entirely.

There is an async version of the fs API, you can access it via require('fs').promises .

In that case, you will have to use await , your code must be an async function. For an utility script that only does one thing, the benefit of doing it that way is questionable.

Answer 2

Replace the appendFile() asynchronous method with the appendFileSync() synchronous method so that code waits until the loop has completed.

 const scriptFiles = fs.readdirSync(scriptsPath).filter(file => file.endsWith(".sql")); for (const file of scriptFiles) { var data = fs.readFileSync(`${scriptsPath}/${file}`, 'utf8'); fs.appendFileSync(`${scriptsPath}/Hotfix.sql`, data.toString() + "\n"); process.stdout.cursorTo(0); } console.log(`start ${scriptsPath}/Hotfix.sql`) exec(`start ${scriptsPath}/Hotfix.sql`)