fs system

const fs = require('fs');
// read file
fs.readFile('./docs/sample.txt', (err, data) => {
    if(err){
        console.log(err);
    }
    console.log(data.toString());
})
console.log("this is last line");
// node will not wait for the function to excute, it will carry on with rest of the code and then come back when the file is read.

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// write file
fs.writeFile('./docs/blog1.txt', 'This is blog line', () => {
    console.log('File was written');
})
// if blog1.txt doesent exist, then node will create the file instead of giving an error.

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// create folder
if(!fs.existsSync('./assets')){
    fs.mkdir('./assets', (err) => {
        if(err){
            console.log(err)
        }
        console.log("folder created");
    })
}else{
    fs.rmdir('./assets', (err) => {
        if(err){
            console.log(err);
        }
        console.log('folder deleted');
    })
}
// existsSync will check if the file exists 

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// delete file
if(fs.existsSync('./docs/deleteme.txt')){
    fs.unlink('./docs/deleteme.txt', (err) => {
        if(err){
            console.log(err)
        }
        console.log('file deleted');
    })
}

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// read stream
const readStream = fs.createReadStream('./docs/lorum.txt', {encoding: 'utf8'})
readStream.on('data', (chunk) => {
    console.log(chunk);
})

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// write stream
const writeStream = fs.createWriteStream('./docs/write.txt');
const readStream = fs.createReadStream('./docs/lorum.txt', {encoding: 'utf8'})
readStream.on('data', (chunk) => {
    writeStream.write('New chunk');
    writeStream.write(chunk);
})

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// piping
const writeStream = fs.createWriteStream('./docs/write.txt');
const readStream = fs.createReadStream('./docs/lorum.txt', {encoding: 'utf8'})
readStream.pipe(writeStream);