diff --git a/badger-am.js b/badger-am.js
index 123797e..d1981be 100755
--- a/badger-am.js
+++ b/badger-am.js
@@ -10,19 +10,11 @@ const audio = require('./lib/audio');
 const util = require('./lib/util');
 const cli = require('./lib/cli');
 
-// generate timestamp
-const start = process.hrtime();
-
 badger();
 
-// "main"
+// main application
 function badger() {
     cli.printLogo();
-    run();
-}
-
-// start from command lines
-function run() {
     // general options
     commander
         .version(app.version)
@@ -38,14 +30,20 @@ function run() {
     commander
         .command('sort <input> <output>')
         .description('sort audio files by tags')
-        .option('-f, --format <type>', 'specify audio format (\'flac\', \'mp3\')', '.flac')
+        .option('-f, --format <format>', 'specify audio format (\'flac\', \'mp3\')', '.flac')
         .action(sort);
     // artwork
     commander
         .command('artwork <input>')
         .description('extract cover artwork')
-        .option('-f, --format <type>', 'specify audio format (\'flac\', \'mp3\')', '.flac')
+        .option('-f, --format <format>', 'specify audio format (\'flac\', \'mp3\')', '.flac')
         .action(artwork);
+    // scan
+    commander
+        .command('scan <input>')
+        .description('scan audio files for missing cover artwork')
+        .option('-f, --format <format>', 'specify audio format (\'flac\', \'mp3\')', '.flac')
+        .action(scan);
     // parse command line arguments
     commander.parse(process.argv);
 }
@@ -58,8 +56,8 @@ function convert(input, output, options) {
         concurrency: commander.concurrency || os.cpus().length,
         bitrate: options.bitrate || 320,
         format: options.format || '.flac'
-    }, function (err) {
-        cli.exit(err);
+    }, function (err, time) {
+        cli.exit(err, time);
     });
 }
 
@@ -71,7 +69,7 @@ function sort(input, output, options) {
         concurrency: commander.concurrency || os.cpus().length,
         bitrate: options.bitrate || 320,
         format: options.format || '.flac'
-    }, function (err) {
+    }, function (err, time) {
         cli.exit(err);
     });
 }
@@ -82,7 +80,12 @@ function artwork(input, options) {
         input: path.normalize(input),
         concurrency: commander.concurrency || os.cpus().length,
         format: options.format || '.flac'
-    }, function (err) {
+    }, function (err, time) {
         cli.exit(err);
     });
+}
+
+// scan files
+function scan(input, options) {
+
 }
\ No newline at end of file
diff --git a/lib/audio.js b/lib/audio.js
index da82255..b842137 100644
--- a/lib/audio.js
+++ b/lib/audio.js
@@ -10,6 +10,7 @@ const cli = require('./cli');
 
 // convert all files in input directory
 function batchConvert(config, callback) {
+    let timestamp = process.hrtime();
     async.waterfall([
         // get files
         function (waterfallCallback) {
@@ -17,7 +18,8 @@ function batchConvert(config, callback) {
         },
         // display info, prompt user and create progressbar
         function (files, waterfallCallback) {
-            cli.askForConfirmation(files.length + ' files found.\nstart conversion now?', ['yes', 'y'], function (err) {
+            console.log(files.length + ' files found after ' + util.getTimeDiff(timestamp) + ' seconds');
+            cli.askForConfirmation('start conversion now?', ['yes', 'y'], function (err) {
                 if (err) {
                     return waterfallCallback(err);
                 }
@@ -26,6 +28,7 @@ function batchConvert(config, callback) {
         },
         // process each file
         function (files, bar, waterfallCallback) {
+            timestamp = process.hrtime();
             async.eachLimit(files, config.concurrency, function (file, eachCallback) {
                 convert(file, config, function (err) {
                     bar.tick();
@@ -34,7 +37,12 @@ function batchConvert(config, callback) {
                     }
                     eachCallback();
                 });
-            }, waterfallCallback);
+            }, function (err, result) {
+                if (err) {
+                    return waterfallCallback(err);
+                }
+                waterfallCallback(null, timestamp)
+            });
         }
     ], callback);
 }
@@ -75,6 +83,7 @@ function convert(source, config, callback) {
 
 //
 function batchArtwork(config, callback) {
+    let timestamp = process.hrtime();
     async.waterfall([
         // get files
         function (waterfallCallback) {
@@ -82,7 +91,8 @@ function batchArtwork(config, callback) {
         },
         // display info, prompt user and create progressbar
         function (files, waterfallCallback) {
-            cli.askForConfirmation(files.length + ' files found.\nstart artwork extraction now?', ['yes', 'y'], function (err) {
+            console.log(files.length + ' files found after ' + util.getTimeDiff(timestamp) + ' seconds');
+            cli.askForConfirmation('start artwork extraction now?', ['yes', 'y'], function (err) {
                 if (err) {
                     return waterfallCallback(err);
                 }
@@ -91,6 +101,7 @@ function batchArtwork(config, callback) {
         },
         // process each file
         function (files, bar, waterfallCallback) {
+            timestamp = process.hrtime();
             async.eachLimit(files, config.concurrency, function (file, eachCallback) {
                 extractArtwork(file, function (err) {
                     bar.tick();
@@ -99,7 +110,12 @@ function batchArtwork(config, callback) {
                     }
                     eachCallback();
                 });
-            }, waterfallCallback);
+            }, function (err, result) {
+                if (err) {
+                    return waterfallCallback(err);
+                }
+                waterfallCallback(null, timestamp);
+            });
         }
     ], callback);
 }
diff --git a/lib/cli.js b/lib/cli.js
index 0100a36..8dcb74d 100644
--- a/lib/cli.js
+++ b/lib/cli.js
@@ -1,6 +1,7 @@
 // requirements
 const progress = require('progress');
 const readline = require('readline');
+const util = require('./util');
 
 // print logo
 function printLogo() {
@@ -29,7 +30,7 @@ function askForConfirmation(message, confirms, callback) {
     line.question(message + '\n', function (answer) {
         line.close();
         if (confirms.indexOf(answer) === -1) {
-            return callback('wrong input: \'' + answer + '\'');
+            return callback('aborted by user, answered \'' + answer + '\'');
         }
         callback();
     });
@@ -44,13 +45,12 @@ function createProgressBar(total) {
 }
 
 // shutdown
-function exit(err, start) {
+function exit(err, timestamp) {
     if (err) {
         console.error(err);
         process.exit(1);
     }
-    const diff = process.hrtime(start);
-    console.log('exiting after ' + ((diff[0] + (diff[1] / 1000000)) / 1000).toFixed(2) + ' seconds');
+    console.log('exiting after ' + util.getTimeDiff(timestamp) + ' seconds');
     process.exit(0);
 }
 
diff --git a/lib/util.js b/lib/util.js
index a6ccec2..8dc9ac6 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -9,6 +9,7 @@ const audio = require('./audio');
 
 // move all files from input to output directory
 function batchSort(config, callback) {
+    let timestamp = process.hrtime();
     async.waterfall([
         // get files
         function (waterfallCallback) {
@@ -16,15 +17,17 @@ function batchSort(config, callback) {
         },
         // display info, prompt user and create progressbar
         function (files, waterfallCallback) {
-            cli.askForConfirmation(files.length + ' files found.\nstart sorting now?', ['yes', 'y'], function (err) {
+            console.log(files.length + ' files found after ' + util.getTimeDiff(timestamp) + ' seconds');
+            cli.askForConfirmation('start sorting now?', ['yes', 'y'], function (err) {
                 if (err) {
                     return waterfallCallback(err);
                 }
-            waterfallCallback(null, files, cli.createProgressBar(files.length));
+                waterfallCallback(null, files, cli.createProgressBar(files.length));
             });
         },
         // process each file
         function (files, bar, waterfallCallback) {
+            timestamp = process.hrtime();
             async.eachLimit(files, config.concurrency, function (file, eachCallback) {
                 moveFile(file, config, function (err) {
                     bar.tick();
@@ -33,7 +36,12 @@ function batchSort(config, callback) {
                     }
                     eachCallback();
                 })
-            }, waterfallCallback);
+            }, function (err, result) {
+                if (err) {
+                    return waterfallCallback(err);
+                }
+                waterfallCallback(null, timestamp);
+            });
         }
     ], callback);
 }
@@ -87,12 +95,12 @@ function getPathByMetadata(source, output, metadata, callback) {
                 tmp = metadata.albumartist[counter];
             }
         }
-        filePath = path.join(filePath, replaceSpecialChars(tmp.trim()));
+        filePath = path.join(filePath, replaceIllegalChars(tmp.trim()));
     } else {
-        filePath = path.join(filePath, replaceSpecialChars(metadata.artist[0].trim()));
+        filePath = path.join(filePath, replaceIllegalChars(metadata.artist[0].trim()));
     }
     if (metadata.album) {
-        filePath = path.join(filePath, replaceSpecialChars(metadata.album.trim()));
+        filePath = path.join(filePath, replaceIllegalChars(metadata.album.trim()));
     }
     // define filename
     let fileName = '';
@@ -113,7 +121,7 @@ function getPathByMetadata(source, output, metadata, callback) {
         fileName += metadata.title.trim();
     }
     // append extension
-    fileName += replaceSpecialChars(path.extname(source)).trim();
+    fileName += replaceIllegalChars(path.extname(source)).trim();
     // join directory and name
     callback(null, path.join(filePath, fileName));
 }
@@ -126,12 +134,14 @@ function frontFill(string, fill, length) {
     return string;
 }
 
-function replaceSpecialChars(string) {
+// replace illegal characters
+function replaceIllegalChars(string) {
     return string.replace(/[/\\:*?"<>|]/g, '-');
 }
 
 // list files in directory
 function readDirRecursive(where, extension, callback) {
+    console.log('getting list of \'' + extension + '\' files in directory \'' + where + '\' ...');
     if (extension.indexOf('.') !== 0) {
         extension = '.' + extension;
     }
@@ -141,9 +151,16 @@ function readDirRecursive(where, extension, callback) {
     }
 }
 
+// get difference to timestamp
+function getTimeDiff(timestamp) {
+    const diff = process.hrtime(timestamp);
+    return (diff[0] + diff[1] / 1e9).toFixed(2);
+}
+
 // api
 exports.batchSort = batchSort;
 exports.moveFile = moveFile;
 exports.getPathByMetadata = getPathByMetadata;
 exports.frontFill = frontFill;
-exports.readDirRecursive = readDirRecursive;
\ No newline at end of file
+exports.readDirRecursive = readDirRecursive;
+exports.getTimeDiff = getTimeDiff;
\ No newline at end of file
diff --git a/package.json b/package.json
index 5b4333a..5961b73 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "badger-am",
-  "version": "0.5.3",
+  "version": "0.5.4",
   "license": "MIT",
   "description": "audio manager",
   "author": "Daniel Sommer <daniel.sommer@velvettear.de>",