handles overwriting

README.md

@@ -346,6 +346,30 @@ downloader('path/to-binary', function error(err, done) {
 })
 ```
 
+This script parses a couple of flags from `argv`:
+
+* `--platform=windows` forces downloading the Windows version of youtube-dl.
+* `--overwrite` overwrites the existing youtube-dl executable if it exists.
+
+
+### Update (promise version)
+
+If you are using promises there's now a promise version.
+
+``` js
+const downloader = require('youtube-dl/lib/downloaderPromise')
+
+downloader('path/to-binary')
+.then((message) => {
+    console.log(message);
+}).catch((err) => {
+    console.log("err", err);
+    exit(1);
+});
+
+```
+
+
 ### Environment Variables
 
 Youtube-dl looks for certain environment variables to aid its operations. If Youtube-dl doesn't find them in the environment during the installation step, a lowercased variant of these variables will be used from the [npm config](https://docs.npmjs.com/cli/config) or [yarn config](https://yarnpkg.com/lang/en/docs/cli/config/).

lib/downloader.js

@@ -8,6 +8,7 @@ const fs = require('fs')
 const [, , ...flags] = process.argv
 
 const isWin = flags.includes('--platform=windows') || require('./util').isWin
+const isOverwrite = flags.includes('--overwrite')
 
 // First, look for the download link.
 let dir, filePath
@@ -44,25 +45,30 @@ function download (url, callback) {
         status = new Error('Response Error: ' + res.statusCode)
         return
       }
-      downloadFile.pipe(fs.createWriteStream(filePath, { mode: 493 }))
+
+      const outputStream = fs.createWriteStream(filePath, { mode: 493 });
+      outputStream.on(
+        'close',
+        function end() {
+          callback(status, newVersion);
+        });
+      downloadFile.pipe(outputStream);
     })
 
     downloadFile.on('error', function error (err) {
       callback(err)
     })
-
-    downloadFile.on('end', function end () {
-      callback(status, newVersion)
-    })
   })
 }
 
 const exec = path => (isWin ? path + '.exe' : path)
 
 function createBase (binDir) {
   dir = binDir || defaultBin
-  mkdirp.sync(dir)
-  if (binDir) mkdirp.sync(defaultBin)
+  if (!fs.existsSync(dir)) {
+    mkdirp.sync(dir)
+    if (binDir) mkdirp.sync(defaultBin)
+  }
   filePath = path.join(dir, exec('youtube-dl'))
 }
 
@@ -74,6 +80,21 @@ function downloader (binDir, callback) {
 
   createBase(binDir)
 
+  // handle overwritin
+  if (fs.existsSync(filePath)) {
+    if (!isOverwrite) {
+      return callback("File exists");
+    }
+    else {
+      try {
+        fs.unlinkSync(filePath);
+      }
+      catch (e) {
+        callback(e);
+      }
+    }
+  }
+
   download(url, function error (err, newVersion) {
     if (err) return callback(err)
     fs.writeFileSync(