diff --git a/CMakeLists.txt b/CMakeLists.txt
index 587c016..78e1f2e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.12)
 
 list(PREPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 
-project(mediacopier VERSION 2.1.0)
+project(MediaCopier VERSION 2.1.1)
 
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
diff --git a/mediacopier-cli/source/config.cpp b/mediacopier-cli/source/config.cpp
index 28ee0b1..b4e3104 100644
--- a/mediacopier-cli/source/config.cpp
+++ b/mediacopier-cli/source/config.cpp
@@ -16,13 +16,12 @@
 
 #include "config.hpp"
 
-#include <CLI/CLI.hpp>
+#include <mediacopier/version.hpp>
 
+#include <CLI/CLI.hpp>
 #include <spdlog/spdlog.h>
 #include <toml.hpp>
 
-#include <mediacopier/version.hpp>
-
 #include <filesystem>
 #include <fstream>
 
@@ -96,3 +95,31 @@ void Config::finalize() noexcept
         pattern = DEFAULT_PATTERN;
     }
 }
+
+bool Config::validate() const noexcept
+{
+    bool result = false;
+    if (pattern.empty()) {
+        spdlog::error("No pattern specified!");
+        result = true;
+    }
+    try {
+        if (fs::absolute(outputDir).empty() || !fs::is_directory(inputDir)) {
+            spdlog::error("Input directory does not exist!");
+            result = true;
+        }
+    } catch(const fs::filesystem_error& err) {
+        spdlog::error("Failed to validate input directory path: " + std::string{err.what()});
+        result = true;
+    }
+    try {
+        if (fs::absolute(outputDir).empty()) {
+            spdlog::error("No output directory specified");
+            result = true;
+        }
+    } catch(const fs::filesystem_error& err) {
+        spdlog::error("Failed to validate output directory path: " + std::string{err.what()});
+        result = true;
+    }
+    return result;
+}
diff --git a/mediacopier-cli/source/config.hpp b/mediacopier-cli/source/config.hpp
index 8e16a26..e5d5ec6 100644
--- a/mediacopier-cli/source/config.hpp
+++ b/mediacopier-cli/source/config.hpp
@@ -32,6 +32,7 @@ struct Config
     void loadPersistentConfig();
     void storePersistentConfig() const;
     void finalize() noexcept;
+    bool validate() const noexcept;
 
     Command cmd = Command::Copy;
     std::filesystem::path inputDir;
diff --git a/mediacopier-cli/source/main.cpp b/mediacopier-cli/source/main.cpp
index 20e4a1d..86bdfd5 100644
--- a/mediacopier-cli/source/main.cpp
+++ b/mediacopier-cli/source/main.cpp
@@ -60,7 +60,7 @@ auto exec(const Config& config) -> void
     });
 
     spdlog::info("Checking input directory..");
-    auto reg = mc::FileRegister{config.outputDir, config.pattern};
+    auto fileRegister = mc::FileRegister{config.outputDir, config.pattern};
     std::optional<fs::path> dest;
 
     for (auto file : valid_media_files(config.inputDir)) {
@@ -69,7 +69,7 @@ auto exec(const Config& config) -> void
             break;
         }
         try {
-            if ((dest = reg.add(file)).has_value()) {
+            if ((dest = fileRegister.add(file)).has_value()) {
                 spdlog::info("Processing: {} -> {}",
                              file->path().string(),
                              dest.value().string());
@@ -82,7 +82,7 @@ auto exec(const Config& config) -> void
     }
 
     spdlog::info("Removing duplicates in destination directory..");
-    reg.removeDuplicates();
+    fileRegister.removeDuplicates();
 
     spdlog::info("Done");
     std::signal(SIGINT, SIG_DFL);
@@ -98,6 +98,11 @@ int main(int argc, char *argv[])
     config.loadPersistentConfig();
     config.finalize();
 
+    if (config.validate()) {
+        spdlog::error("Invalid configuration");
+        return 1;
+    }
+
     switch (config.cmd) {
     case Config::Command::Copy:
         exec<mediacopier::FileOperationCopyJpeg>(config);
diff --git a/mediacopier-lib/source/operation_simulate.cpp b/mediacopier-lib/source/operation_simulate.cpp
index 535bef2..b015922 100644
--- a/mediacopier-lib/source/operation_simulate.cpp
+++ b/mediacopier-lib/source/operation_simulate.cpp
@@ -20,25 +20,31 @@
 #include <mediacopier/file_info_video.hpp>
 #include <spdlog/spdlog.h>
 
+#include <chrono>
+#include <thread>
+
 namespace mediacopier {
 
 auto FileOperationSimulate::dumpFilePaths(const AbstractFileInfo& file) const -> void
 {
-    spdlog::info(m_destination.string() + " (from " + file.path().string() + ")");
+    spdlog::info("{} -> {}", file.path().string(), m_destination.string());
 }
 
 auto FileOperationSimulate::visit(const FileInfoImage& file) -> void
 {
+    std::this_thread::sleep_for(std::chrono::milliseconds(200));
     dumpFilePaths(file);
 }
 
 auto FileOperationSimulate::visit(const FileInfoImageJpeg& file) -> void
 {
+    std::this_thread::sleep_for(std::chrono::milliseconds(200));
     dumpFilePaths(file);
 }
 
 auto FileOperationSimulate::visit(const FileInfoVideo& file) -> void
 {
+    std::this_thread::sleep_for(std::chrono::milliseconds(200));
     dumpFilePaths(file);
 }
 
diff --git a/mediacopier-qt/lang/README.md b/mediacopier-qt/lang/README.md
new file mode 100644
index 0000000..609d6b3
--- /dev/null
+++ b/mediacopier-qt/lang/README.md
@@ -0,0 +1,5 @@
+You can update the translations via
+
+```sh
+linguist-qt5 mediacopier-qt/lang/lang_de.ts
+```
diff --git a/mediacopier-qt/lang/lang_de.ts b/mediacopier-qt/lang/lang_de.ts
index 0edaecf..46bb3ff 100644
--- a/mediacopier-qt/lang/lang_de.ts
+++ b/mediacopier-qt/lang/lang_de.ts
@@ -5,21 +5,14 @@
     <name>Command</name>
     <message>
         <location filename="../source/config.cpp" line="35"/>
-        <location filename="../source/config.cpp" line="36"/>
         <source>Copy</source>
         <translation>Kopieren</translation>
     </message>
     <message>
-        <location filename="../source/config.cpp" line="37"/>
-        <location filename="../source/config.cpp" line="38"/>
+        <location filename="../source/config.cpp" line="36"/>
         <source>Move</source>
         <translation>Verschieben</translation>
     </message>
-    <message>
-        <location filename="../source/config.cpp" line="39"/>
-        <source>Simulate</source>
-        <translation>Simulation</translation>
-    </message>
 </context>
 <context>
     <name>KMediaCopierJob</name>
@@ -45,28 +38,34 @@
 <context>
     <name>MediaCopierParamWidget</name>
     <message>
-        <location filename="../source/gui/MediaCopierParamWidget.ui" line="30"/>
+        <location filename="../source/gui/MediaCopierParamWidget.ui" line="89"/>
         <source>Operation</source>
         <translation></translation>
     </message>
     <message>
-        <location filename="../source/gui/MediaCopierParamWidget.ui" line="40"/>
+        <location filename="../source/gui/MediaCopierParamWidget.ui" line="30"/>
         <source>Input</source>
         <translation>Quellverzeichnis</translation>
     </message>
     <message>
-        <location filename="../source/gui/MediaCopierParamWidget.ui" line="50"/>
+        <location filename="../source/gui/MediaCopierParamWidget.ui" line="76"/>
         <source>Pattern</source>
         <translation>Schema</translation>
     </message>
     <message>
-        <location filename="../source/gui/MediaCopierParamWidget.ui" line="60"/>
+        <location filename="../source/gui/MediaCopierParamWidget.ui" line="66"/>
         <source>Output</source>
         <translation>Zielverzeichnis</translation>
     </message>
     <message>
-        <location filename="../source/gui/MediaCopierParamWidget.ui" line="73"/>
-        <location filename="../source/gui/MediaCopierParamWidget.ui" line="83"/>
+        <location filename="../source/gui/MediaCopierParamWidget.ui" line="139"/>
+        <source>Update</source>
+        <translatorcomment>Ändern</translatorcomment>
+        <translation>Ändern</translation>
+    </message>
+    <message>
+        <location filename="../source/gui/MediaCopierParamWidget.ui" line="46"/>
+        <location filename="../source/gui/MediaCopierParamWidget.ui" line="53"/>
         <source>...</source>
         <translation></translation>
     </message>
@@ -74,12 +73,12 @@
 <context>
     <name>QObject</name>
     <message>
-        <location filename="../source/gui/MediaCopierParamWidget.cpp" line="98"/>
+        <location filename="../source/gui/MediaCopierParamWidget.cpp" line="132"/>
         <source>Source folder</source>
         <translation>Quellverzeichnis</translation>
     </message>
     <message>
-        <location filename="../source/gui/MediaCopierParamWidget.cpp" line="103"/>
+        <location filename="../source/gui/MediaCopierParamWidget.cpp" line="137"/>
         <source>Destination folder</source>
         <translation>Zielverzeichnis</translation>
     </message>
diff --git a/mediacopier-qt/source/config.cpp b/mediacopier-qt/source/config.cpp
index 50eb806..ece0d4e 100644
--- a/mediacopier-qt/source/config.cpp
+++ b/mediacopier-qt/source/config.cpp
@@ -24,19 +24,16 @@
 namespace fs = std::filesystem;
 
 static constexpr const char* CONFIG_FILE = ".mediacopier";
+static constexpr const char* DEFAULT_PATTERN = "%Y/%W/IMG_%Y%m%d_%H%M%S";
 
 static const std::map<QString, Config::Command> commands = {
-    {"copy", Config::Command::COPY_JPEG},
-    {"move", Config::Command::MOVE_JPEG},
-    {"sim", Config::Command::SIMULATE}
+    {"copy", Config::Command::COPY},
+    {"move", Config::Command::MOVE}
 };
 
 static const std::map<Config::Command, QString> commandStrings = {
     {Config::Command::COPY, QT_TRANSLATE_NOOP("Command", "Copy")},
-    {Config::Command::COPY_JPEG, QT_TRANSLATE_NOOP("Command", "Copy")},
-    {Config::Command::MOVE, QT_TRANSLATE_NOOP("Command", "Move")},
-    {Config::Command::MOVE_JPEG, QT_TRANSLATE_NOOP("Command", "Move")},
-    {Config::Command::SIMULATE, QT_TRANSLATE_NOOP("Command", "Simulate")}
+    {Config::Command::MOVE, QT_TRANSLATE_NOOP("Command", "Move")}
 };
 
 Config::Config(const QApplication& app)
@@ -45,52 +42,38 @@ Config::Config(const QApplication& app)
 
     parser.setApplicationDescription(
                 app.applicationName() +
-                ", Copyright (C) 2020-2023 Patrick Ziegler");
-
+                ", Copyright (C) 2020-2024 Patrick Ziegler");
+    parser.addPositionalArgument(
+                "CMD", "Available commands: copy (default), move", "[CMD");
     parser.addPositionalArgument(
                 "SRC", "Input directory", "[SRC");
-
     parser.addPositionalArgument(
-                "DST", "Output directory", "[DST]]");
-
-    QCommandLineOption optCommand(
-                "c", "Available commands: copy (default), move, sim",
-                "command");
-
-    QCommandLineOption optPattern(
-                "f", "Pattern to be used for creating new filenames",
-                "pattern");
-
+                "DST", "Output directory", "[DST]]]");
     QCommandLineOption optSlimGui(
                 "slim-gui", "Pattern to be used for creating new filenames");
-
     QCommandLineOption optNoGui(
                 "no-gui", "Pattern to be used for creating new filenames");
 
-    parser.addOptions({optCommand, optPattern, optSlimGui, optNoGui});
+    parser.addOptions({optSlimGui, optNoGui});
     parser.addVersionOption();
     parser.addHelpOption();
     parser.process(app);
 
-    if (parser.positionalArguments().length() > 0)
-        setInputDir(parser.positionalArguments().at(0));
-
-    if (parser.positionalArguments().length() > 1)
-        setOutputDir(parser.positionalArguments().at(1));
-
-    readConfigFile();
-
-    if (parser.isSet("f"))
-        setPattern(parser.value("f"));
-
-    if (parser.isSet("c"))
-        setCommand(parser.value("c"));
-
-    if (parser.isSet("slim-gui"))
-        m_ui = UI::SlimGui;
+    if (parser.positionalArguments().length() > 0) {
+        setCommand(parser.positionalArguments().at(0));
+    }
+    if (parser.positionalArguments().length() > 1) {
+        setInputDir(parser.positionalArguments().at(1));
+    }
+    if (parser.positionalArguments().length() > 2) {
+        setOutputDir(parser.positionalArguments().at(2));
+        readConfigFile();
+    }
+    if (parser.isSet("slim-gui")) {
+        m_guiType = GuiType::Slim;
+    }
 
-    if (parser.isSet("no-gui"))
-        m_ui = UI::NoGui;
+    m_pattern = DEFAULT_PATTERN;
 }
 
 bool Config::readConfigFile() noexcept
@@ -141,6 +124,11 @@ void Config::setPattern(const QString& pattern)
     m_pattern = pattern.toStdString();
 }
 
+void Config::resetPattern()
+{
+    m_pattern = DEFAULT_PATTERN;
+}
+
 void Config::setInputDir(const QString& inputDir)
 {
     m_inputDir = inputDir.toStdString();
diff --git a/mediacopier-qt/source/config.hpp b/mediacopier-qt/source/config.hpp
index 66604a8..5d2998d 100644
--- a/mediacopier-qt/source/config.hpp
+++ b/mediacopier-qt/source/config.hpp
@@ -24,16 +24,12 @@ class Config {
 public:
     enum class Command {
         COPY,
-        MOVE,
-        COPY_JPEG,
-        MOVE_JPEG,
-        SIMULATE
+        MOVE
     };
 
-    enum class UI {
-        FullGui,
-        SlimGui,
-        NoGui
+    enum class GuiType {
+        Full,
+        Slim,
     };
 
     Config(const QApplication& app);
@@ -44,21 +40,22 @@ class Config {
     void setCommand(const Command& command);
     void setCommand(const QString& command);
     void setPattern(const QString& pattern);
+    void resetPattern();
     void setInputDir(const QString& inputDir);
     void setOutputDir(const QString& outputDir);
 
     static const QString commandString(const Command& command);
 
     const Command& command() const { return m_command; }
-    const UI& ui() const { return m_ui; }
+    const GuiType& guiType() const { return m_guiType; }
     const std::string& pattern() const { return m_pattern; }
     const std::filesystem::path& inputDir() const { return m_inputDir; }
     const std::filesystem::path& outputDir() const { return m_outputDir; }
 
 private:
-    Command m_command = Command::COPY_JPEG;
-    UI m_ui = UI::FullGui;
-    std::string m_pattern = "%Y/%W/IMG_%Y%m%d_%H%M%S";
+    Command m_command = Command::COPY;
+    GuiType m_guiType = GuiType::Full;
+    std::string m_pattern;
     std::filesystem::path m_inputDir;
     std::filesystem::path m_outputDir;
 };
diff --git a/mediacopier-qt/source/gui/MediaCopierDialogFull.cpp b/mediacopier-qt/source/gui/MediaCopierDialogFull.cpp
index 2359b34..9f91c0c 100644
--- a/mediacopier-qt/source/gui/MediaCopierDialogFull.cpp
+++ b/mediacopier-qt/source/gui/MediaCopierDialogFull.cpp
@@ -56,16 +56,19 @@ void MediaCopierDialogFull::init(std::shared_ptr<Config> config, QApplication& a
     fsm = std::make_unique<QStateMachine>();
 
     auto s1 = new QState();         // waiting for input
-    auto s2 = new QState();         // executing operation
-    auto s3 = new QState();         // aborting operation
-    auto s4 = new QFinalState();    // closing dialog
+    auto s2 = new QState();         // checking parameters
+    auto s3 = new QState();         // executing operation
+    auto s4 = new QState();         // aborting operation
+    auto s5 = new QFinalState();    // closing dialog
 
     s1->addTransition(ui->dialogButtonBox, &QDialogButtonBox::accepted, s2);
-    s1->addTransition(ui->dialogButtonBox, &QDialogButtonBox::rejected, s4);
-    s2->addTransition(ui->dialogButtonBox, &QDialogButtonBox::rejected, s3);
-    s2->addTransition(this, &MediaCopierDialogFull::rejected, s3);
-    s2->addTransition(this, &MediaCopierDialogFull::operationDone, s1);
+    s1->addTransition(ui->dialogButtonBox, &QDialogButtonBox::rejected, s5);
+    s2->addTransition(ui->param, &MediaCopierParamWidget::validParameters, s3);
+    s2->addTransition(ui->param, &MediaCopierParamWidget::invalidParameters, s1);
+    s3->addTransition(ui->dialogButtonBox, &QDialogButtonBox::rejected, s4);
+    s3->addTransition(this, &MediaCopierDialogFull::rejected, s4);
     s3->addTransition(this, &MediaCopierDialogFull::operationDone, s1);
+    s4->addTransition(this, &MediaCopierDialogFull::operationDone, s1);
 
     auto m_btnOk = ui->dialogButtonBox->button(QDialogButtonBox::Ok);
     auto m_btnCancel = ui->dialogButtonBox->button(QDialogButtonBox::Cancel);
@@ -73,17 +76,22 @@ void MediaCopierDialogFull::init(std::shared_ptr<Config> config, QApplication& a
     s1->assignProperty(m_btnOk, "enabled", true);
     s1->assignProperty(m_btnCancel, "enabled", true);
     s2->assignProperty(m_btnOk, "enabled", false);
-    s3->assignProperty(m_btnCancel, "enabled", false);
+    s2->assignProperty(m_btnCancel, "enabled", false);
+    s3->assignProperty(m_btnOk, "enabled", false);
+    s3->assignProperty(m_btnCancel, "enabled", true);
+    s4->assignProperty(m_btnCancel, "enabled", false);
 
     QObject::connect(s1, &QState::entered, this, &MediaCopierDialogFull::awaitOperation);
-    QObject::connect(s2, &QState::entered, this, &MediaCopierDialogFull::startOperation);
-    QObject::connect(s3, &QState::entered, this, &MediaCopierDialogFull::cancelOperation);
+    QObject::connect(s2, &QState::entered, ui->param, &MediaCopierParamWidget::validate);
+    QObject::connect(s3, &QState::entered, this, &MediaCopierDialogFull::startOperation);
+    QObject::connect(s4, &QState::entered, this, &MediaCopierDialogFull::cancelOperation);
     QObject::connect(fsm.get(), &QStateMachine::finished, this, &MediaCopierDialogFull::close);
 
     fsm->addState(s1);
     fsm->addState(s2);
     fsm->addState(s3);
     fsm->addState(s4);
+    fsm->addState(s5);
     fsm->setInitialState(s1);
     fsm->start();
 }
@@ -96,6 +104,7 @@ void MediaCopierDialogFull::aboutToQuit()
 
 void MediaCopierDialogFull::startOperation()
 {
+    this->ui->log->clear();
     worker = std::make_shared<Worker>(*config);
     QObject::connect(worker.get(), &Worker::status, this->ui->log, &MediaCopierLogWidget::update);
     QObject::connect(worker.get(), &Worker::finished, this, &MediaCopierDialogFull::operationDone);
diff --git a/mediacopier-qt/source/gui/MediaCopierDialogSlim.cpp b/mediacopier-qt/source/gui/MediaCopierDialogSlim.cpp
index 482eb7d..c24fe47 100644
--- a/mediacopier-qt/source/gui/MediaCopierDialogSlim.cpp
+++ b/mediacopier-qt/source/gui/MediaCopierDialogSlim.cpp
@@ -55,20 +55,25 @@ void MediaCopierDialogSlim::init(std::shared_ptr<Config> config, QApplication& a
     fsm = std::make_unique<QStateMachine>();
 
     auto s1 = new QState();         // waiting for input
-    auto s2 = new QState();         // executing operation
-    auto s3 = new QFinalState();    // closing dialog
+    auto s2 = new QState();         // checking parameters
+    auto s3 = new QState();         // executing operation
+    auto s4 = new QFinalState();    // closing dialog
 
     s1->addTransition(ui->dialogButtonBox, &QDialogButtonBox::accepted, s2);
-    s1->addTransition(ui->dialogButtonBox, &QDialogButtonBox::rejected, s3);
-    s2->addTransition(this, &MediaCopierDialogSlim::operationDone, s3);
-
-    QObject::connect(s2, &QState::entered, this, &MediaCopierDialogSlim::hide);
-    QObject::connect(s2, &QState::entered, this, &MediaCopierDialogSlim::startOperation);
+    s1->addTransition(ui->dialogButtonBox, &QDialogButtonBox::rejected, s4);
+    s2->addTransition(ui->param, &MediaCopierParamWidget::validParameters, s3);
+    s2->addTransition(ui->param, &MediaCopierParamWidget::invalidParameters, s1);
+    s3->addTransition(this, &MediaCopierDialogSlim::operationDone, s4);
+
+    QObject::connect(s2, &QState::entered, ui->param, &MediaCopierParamWidget::validate);
+    QObject::connect(s3, &QState::entered, this, &MediaCopierDialogSlim::hide);
+    QObject::connect(s3, &QState::entered, this, &MediaCopierDialogSlim::startOperation);
     QObject::connect(fsm.get(), &QStateMachine::finished, this, &MediaCopierDialogSlim::close);
 
     fsm->addState(s1);
     fsm->addState(s2);
     fsm->addState(s3);
+    fsm->addState(s4);
     fsm->setInitialState(s1);
     fsm->start();
 }
diff --git a/mediacopier-qt/source/gui/MediaCopierLogWidget.cpp b/mediacopier-qt/source/gui/MediaCopierLogWidget.cpp
index 75e67ea..1a54967 100644
--- a/mediacopier-qt/source/gui/MediaCopierLogWidget.cpp
+++ b/mediacopier-qt/source/gui/MediaCopierLogWidget.cpp
@@ -29,7 +29,10 @@ MediaCopierLogWidget::MediaCopierLogWidget(QWidget *parent) :
     QWidget(parent), ui(new Ui::MediaCopierLogWidget)
 {
     ui->setupUi(this);
-
+    ui->logText->setPlainText(
+                QString("%1 v%2")
+                .arg(mediacopier::MEDIACOPIER_PROJECT_NAME)
+                .arg(mediacopier::MEDIACOPIER_VERSION));
     auto sink = std::make_shared<spdlog::sinks::qt_sink_st>(ui->logText, "appendPlainText");
     spdlog::default_logger()->sinks().push_back(std::move(sink));
 }
@@ -39,6 +42,12 @@ MediaCopierLogWidget::~MediaCopierLogWidget()
     delete ui;
 }
 
+void MediaCopierLogWidget::clear()
+{
+    ui->logProgressBar->setValue(0);
+    ui->logText->clear();
+}
+
 void MediaCopierLogWidget::update(Status info)
 {
     ui->logProgressBar->setMaximum(info.fileCount());
diff --git a/mediacopier-qt/source/gui/MediaCopierLogWidget.hpp b/mediacopier-qt/source/gui/MediaCopierLogWidget.hpp
index 8c39645..63229a1 100644
--- a/mediacopier-qt/source/gui/MediaCopierLogWidget.hpp
+++ b/mediacopier-qt/source/gui/MediaCopierLogWidget.hpp
@@ -33,6 +33,7 @@ class MediaCopierLogWidget : public QWidget
 public:
     explicit MediaCopierLogWidget(QWidget *parent=nullptr);
     ~MediaCopierLogWidget();
+    void clear();
 
 public Q_SLOTS:
     void update(Status info);
diff --git a/mediacopier-qt/source/gui/MediaCopierParamWidget.cpp b/mediacopier-qt/source/gui/MediaCopierParamWidget.cpp
index ca78826..467f764 100644
--- a/mediacopier-qt/source/gui/MediaCopierParamWidget.cpp
+++ b/mediacopier-qt/source/gui/MediaCopierParamWidget.cpp
@@ -19,6 +19,7 @@
 
 #include <QAbstractButton>
 #include <QFileDialog>
+#include <QCheckBox>
 
 #include <spdlog/spdlog.h>
 
@@ -33,9 +34,8 @@ const auto ask_for_directory = [](const QString& title) -> QString
 };
 
 static const QList<Config::Command> commands = {
-    Config::Command::COPY_JPEG,
-    Config::Command::MOVE_JPEG,
-    Config::Command::SIMULATE
+    Config::Command::COPY,
+    Config::Command::MOVE
 };
 
 MediaCopierParamWidget::MediaCopierParamWidget(QWidget *parent) :
@@ -47,6 +47,7 @@ MediaCopierParamWidget::MediaCopierParamWidget(QWidget *parent) :
     Q_FOREACH(Config::Command item, commands) {
         ui->paramCommand->addItem(Config::commandString(item));
     }
+    ui->paramPattern->setEnabled(false);
 }
 
 MediaCopierParamWidget::~MediaCopierParamWidget()
@@ -56,9 +57,17 @@ MediaCopierParamWidget::~MediaCopierParamWidget()
 
 void MediaCopierParamWidget::init(std::shared_ptr<Config> config)
 {
-    this->config = std::move(config);
+    m_config = std::move(config);
 
-    syncConfig();
+    ui->dirsInputDirText->setText(QString::fromStdString(m_config->inputDir().string()));
+    ui->dirsOutputDirText->setText(QString::fromStdString(m_config->outputDir().string()));
+    ui->paramPattern->setText(m_config->pattern().c_str());
+    for (int i = 0; i < commands.length(); ++i) {
+        if (commands.at(i) == m_config->command()) {
+            ui->paramCommand->setCurrentIndex(i);
+            break;
+        }
+    }
 
     connect(ui->dirsInputDirButton, &QToolButton::clicked,
             this, &MediaCopierParamWidget::onOpenInputDirClicked);
@@ -66,6 +75,9 @@ void MediaCopierParamWidget::init(std::shared_ptr<Config> config)
     connect(ui->dirsOutputDirButton, &QToolButton::clicked,
             this, &MediaCopierParamWidget::onOpenOutputDirClicked);
 
+    connect(ui->paramPatternUpdate, &QCheckBox::clicked,
+            this, &MediaCopierParamWidget::onPatternUpdateClicked);
+
     connect(ui->dirsInputDirText, &QLineEdit::textChanged,
             this, &MediaCopierParamWidget::onInputDirChanged);
 
@@ -79,17 +91,39 @@ void MediaCopierParamWidget::init(std::shared_ptr<Config> config)
             this, &MediaCopierParamWidget::onCommandChanged);
 }
 
-void MediaCopierParamWidget::syncConfig()
+void MediaCopierParamWidget::validate()
 {
-    ui->dirsInputDirText->setText(QString::fromStdString(config->inputDir().string()));
-    ui->dirsOutputDirText->setText(QString::fromStdString(config->outputDir().string()));
-    ui->paramPattern->setText(config->pattern().c_str());
+    bool result = true;
 
-    for (int i = 0; i < commands.length(); ++i) {
-        if (commands.at(i) == config->command()) {
-            ui->paramCommand->setCurrentIndex(i);
-            break;
-        }
+    QPalette errorPalette;
+    errorPalette.setColor(QPalette::Base, QColor(255, 145, 145));
+    errorPalette.setColor(QPalette::Text, Qt::white);
+
+    if (ui->dirsInputDirText->text().isEmpty() || !QDir(ui->dirsInputDirText->text()).exists()) {
+        ui->dirsInputDirText->setPalette(errorPalette);
+        result = false;
+    } else {
+        ui->dirsInputDirText->setPalette(this->style()->standardPalette());
+    }
+
+    if (ui->dirsOutputDirText->text().isEmpty() || !QDir(ui->dirsOutputDirText->text()).makeAbsolute()) {
+        ui->dirsOutputDirText->setPalette(errorPalette);
+        result = false;
+    } else {
+        ui->dirsOutputDirText->setPalette(this->style()->standardPalette());
+    }
+
+    if (ui->paramPattern->text().isEmpty()) {
+        ui->paramPattern->setPalette(errorPalette);
+        result = false;
+    } else {
+        ui->paramPattern->setPalette(this->style()->standardPalette());
+    }
+
+    if (result) {
+        validParameters();
+    } else {
+        invalidParameters();
     }
 }
 
@@ -103,28 +137,43 @@ void MediaCopierParamWidget::onOpenOutputDirClicked()
     ui->dirsOutputDirText->setText(ask_for_directory(QObject::tr("Destination folder")));
 }
 
+void MediaCopierParamWidget::onPatternUpdateClicked(bool checked)
+{
+    ui->paramPattern->setEnabled(checked);
+    if (!checked) {
+        m_config->resetPattern();
+        m_config->readConfigFile();
+        ui->paramPattern->setText(m_config->pattern().c_str());
+    }
+}
+
 void MediaCopierParamWidget::onInputDirChanged(const QString& text)
 {
-    config->setInputDir(text);
-    spdlog::debug("Changed input dir to " + config->outputDir().string());
+    m_config->setInputDir(text);
+    spdlog::debug("Changed input dir to " + m_config->outputDir().string());
 }
 
 void MediaCopierParamWidget::onOutputDirChanged(const QString& text)
 {
-    config->setOutputDir(text);
-    spdlog::debug("Changed output dir to " + config->outputDir().string());
-    config->readConfigFile();
-    syncConfig();
+    m_config->setOutputDir(text);
+    spdlog::debug("Changed output dir to " + m_config->outputDir().string());
+    if (!ui->paramPattern->isEnabled()) {
+        m_config->resetPattern();
+        if (QDir(text).exists()) {
+            m_config->readConfigFile();
+        }
+    }
+    ui->paramPattern->setText(m_config->pattern().c_str());
 }
 
 void MediaCopierParamWidget::onPatternChanged(const QString& text)
 {
-    config->setPattern(text);
-    spdlog::debug("Changed pattern to " + config->pattern());
+    m_config->setPattern(text);
+    spdlog::debug("Changed pattern to " + m_config->pattern());
 }
 
 void MediaCopierParamWidget::onCommandChanged(int index)
 {
-    config->setCommand(commands.at(index));
+    m_config->setCommand(commands.at(index));
     spdlog::debug("Changed command to " + Config::commandString(commands.at(index)).toStdString());
 }
diff --git a/mediacopier-qt/source/gui/MediaCopierParamWidget.hpp b/mediacopier-qt/source/gui/MediaCopierParamWidget.hpp
index 0ef63fe..77e93a9 100644
--- a/mediacopier-qt/source/gui/MediaCopierParamWidget.hpp
+++ b/mediacopier-qt/source/gui/MediaCopierParamWidget.hpp
@@ -32,13 +32,16 @@ class MediaCopierParamWidget : public QWidget
     explicit MediaCopierParamWidget(QWidget *parent=nullptr);
     ~MediaCopierParamWidget();
     void init(std::shared_ptr<Config> config);
+    void validate();
 
-private:
-    void syncConfig();
+Q_SIGNALS:
+    void validParameters();
+    void invalidParameters();
 
 private Q_SLOTS:
     void onOpenInputDirClicked();
     void onOpenOutputDirClicked();
+    void onPatternUpdateClicked(bool checked);
     void onInputDirChanged(const QString& text);
     void onOutputDirChanged(const QString& text);
     void onPatternChanged(const QString& text);
@@ -46,5 +49,5 @@ private Q_SLOTS:
 
 private:
     Ui::MediaCopierParamWidget *ui;
-    std::shared_ptr<Config> config;
+    std::shared_ptr<Config> m_config;
 };
diff --git a/mediacopier-qt/source/gui/MediaCopierParamWidget.ui b/mediacopier-qt/source/gui/MediaCopierParamWidget.ui
index 96ac463..5d4d124 100644
--- a/mediacopier-qt/source/gui/MediaCopierParamWidget.ui
+++ b/mediacopier-qt/source/gui/MediaCopierParamWidget.ui
@@ -7,8 +7,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>160</width>
-    <height>150</height>
+    <width>187</width>
+    <height>122</height>
    </rect>
   </property>
   <layout class="QGridLayout" name="gridLayout">
@@ -24,33 +24,39 @@
    <property name="bottomMargin">
     <number>0</number>
    </property>
-   <item row="5" column="0">
-    <widget class="QLabel" name="paramCommandLabel">
+   <item row="0" column="0">
+    <widget class="QLabel" name="dirsInputDirLabel">
      <property name="text">
-      <string>Operation</string>
+      <string>Input</string>
      </property>
      <property name="alignment">
       <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
      </property>
     </widget>
    </item>
-   <item row="0" column="0">
-    <widget class="QLabel" name="dirsInputDirLabel">
+   <item row="5" column="2" colspan="2">
+    <widget class="QComboBox" name="paramCommand"/>
+   </item>
+   <item row="0" column="2">
+    <widget class="QLineEdit" name="dirsInputDirText"/>
+   </item>
+   <item row="2" column="3">
+    <widget class="QToolButton" name="dirsOutputDirButton">
      <property name="text">
-      <string>Input</string>
-     </property>
-     <property name="alignment">
-      <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
+      <string>...</string>
      </property>
     </widget>
    </item>
-   <item row="3" column="0">
-    <widget class="QLabel" name="paramBaseFormatLabel">
+   <item row="0" column="3">
+    <widget class="QToolButton" name="dirsInputDirButton">
      <property name="text">
-      <string>Pattern</string>
+      <string>...</string>
      </property>
-     <property name="alignment">
-      <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
+     <property name="popupMode">
+      <enum>QToolButton::DelayedPopup</enum>
+     </property>
+     <property name="arrowType">
+      <enum>Qt::NoArrow</enum>
      </property>
     </widget>
    </item>
@@ -64,42 +70,79 @@
      </property>
     </widget>
    </item>
-   <item row="2" column="1">
-    <widget class="QLineEdit" name="dirsOutputDirText"/>
-   </item>
-   <item row="2" column="2">
-    <widget class="QToolButton" name="dirsOutputDirButton">
+   <item row="3" column="0">
+    <widget class="QLabel" name="paramPatternLabel">
      <property name="text">
-      <string>...</string>
+      <string>Pattern</string>
+     </property>
+     <property name="alignment">
+      <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
      </property>
     </widget>
    </item>
-   <item row="0" column="1">
-    <widget class="QLineEdit" name="dirsInputDirText"/>
+   <item row="2" column="2">
+    <widget class="QLineEdit" name="dirsOutputDirText"/>
    </item>
-   <item row="0" column="2">
-    <widget class="QToolButton" name="dirsInputDirButton">
+   <item row="5" column="0">
+    <widget class="QLabel" name="paramCommandLabel">
      <property name="text">
-      <string>...</string>
-     </property>
-     <property name="popupMode">
-      <enum>QToolButton::DelayedPopup</enum>
+      <string>Operation</string>
      </property>
-     <property name="arrowType">
-      <enum>Qt::NoArrow</enum>
+     <property name="alignment">
+      <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
      </property>
     </widget>
    </item>
-   <item row="3" column="1" colspan="2">
-    <widget class="QLineEdit" name="paramPattern">
-     <property name="text">
-      <string/>
+   <item row="3" column="2" colspan="2">
+    <widget class="QFrame" name="paramPatternFrame">
+     <property name="sizePolicy">
+      <sizepolicy hsizetype="Preferred" vsizetype="Fixed">
+       <horstretch>0</horstretch>
+       <verstretch>0</verstretch>
+      </sizepolicy>
+     </property>
+     <property name="frameShape">
+      <enum>QFrame::NoFrame</enum>
+     </property>
+     <property name="frameShadow">
+      <enum>QFrame::Plain</enum>
      </property>
+     <property name="lineWidth">
+      <number>0</number>
+     </property>
+     <layout class="QHBoxLayout" name="horizontalLayout">
+      <property name="spacing">
+       <number>6</number>
+      </property>
+      <property name="leftMargin">
+       <number>0</number>
+      </property>
+      <property name="topMargin">
+       <number>0</number>
+      </property>
+      <property name="rightMargin">
+       <number>0</number>
+      </property>
+      <property name="bottomMargin">
+       <number>0</number>
+      </property>
+      <item>
+       <widget class="QLineEdit" name="paramPattern">
+        <property name="text">
+         <string/>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QCheckBox" name="paramPatternUpdate">
+        <property name="text">
+         <string>Update</string>
+        </property>
+       </widget>
+      </item>
+     </layout>
     </widget>
    </item>
-   <item row="5" column="1" colspan="2">
-    <widget class="QComboBox" name="paramCommand"/>
-   </item>
   </layout>
  </widget>
  <tabstops>
@@ -107,6 +150,7 @@
   <tabstop>dirsInputDirButton</tabstop>
   <tabstop>dirsOutputDirText</tabstop>
   <tabstop>dirsOutputDirButton</tabstop>
+  <tabstop>paramPatternUpdate</tabstop>
   <tabstop>paramPattern</tabstop>
   <tabstop>paramCommand</tabstop>
  </tabstops>
diff --git a/mediacopier-qt/source/kde/mediacopier.desktop.in b/mediacopier-qt/source/kde/mediacopier.desktop.in
index 89bda29..887c74d 100644
--- a/mediacopier-qt/source/kde/mediacopier.desktop.in
+++ b/mediacopier-qt/source/kde/mediacopier.desktop.in
@@ -12,10 +12,10 @@ X-KDE-Priority=TopLevel
 Name=Copy media files to ...
 Name[de]=Medien kopieren nach ...
 Icon=folder-copy
-Exec=@CMAKE_INSTALL_PREFIX@/bin/@EXECUTABLE_NAME@ --slim-gui -c copy "%U"
+Exec=@CMAKE_INSTALL_PREFIX@/bin/@EXECUTABLE_NAME@ --slim-gui copy "%U"
 
 [Desktop Action mediacopier-move]
 Name=Move media files to ...
 Name[de]=Medien verschieben nach ...
 Icon=folder-move
-Exec=@CMAKE_INSTALL_PREFIX@/bin/@EXECUTABLE_NAME@ --slim-gui -c move "%U"
+Exec=@CMAKE_INSTALL_PREFIX@/bin/@EXECUTABLE_NAME@ --slim-gui move "%U"
diff --git a/mediacopier-qt/source/main.cpp b/mediacopier-qt/source/main.cpp
index e295873..f3ec7ea 100644
--- a/mediacopier-qt/source/main.cpp
+++ b/mediacopier-qt/source/main.cpp
@@ -16,7 +16,6 @@
 
 #include "gui/MediaCopierDialogFull.hpp"
 #include "gui/MediaCopierDialogSlim.hpp"
-#include "worker.hpp"
 
 #include <mediacopier/version.hpp>
 
@@ -34,21 +33,6 @@ int run_gui(QApplication& app, std::shared_ptr<Config> config)
     return app.exec();
 }
 
-int run_cli(QApplication& app, std::shared_ptr<Config> config)
-{
-    Worker worker{*config};
-    worker.start();
-    return app.exec();
-}
-
-using UiFuncType = std::function<int(QApplication&, std::shared_ptr<Config>)>;
-
-static const std::map<Config::UI, UiFuncType> uiFuncMap = {
-    {Config::UI::FullGui, &run_gui<MediaCopierDialogFull>},
-    {Config::UI::SlimGui, &run_gui<MediaCopierDialogSlim>},
-    {Config::UI::NoGui, &run_cli},
-};
-
 int main(int argc, char *argv[])
 {
     try {
@@ -62,8 +46,13 @@ int main(int argc, char *argv[])
         app.setApplicationVersion(mediacopier::MEDIACOPIER_VERSION);
 
         auto config = std::make_shared<Config>(app);
-        return uiFuncMap.at(config->ui())(app, config);
 
+        switch (config->guiType()) {
+        case Config::GuiType::Full:
+            return run_gui<MediaCopierDialogFull>(app, config);
+        case Config::GuiType::Slim:
+            return run_gui<MediaCopierDialogSlim>(app, config);
+        }
     } catch (const std::exception& err) {
         spdlog::error(err.what());
         return 1;
diff --git a/mediacopier-qt/source/worker.cpp b/mediacopier-qt/source/worker.cpp
index 7b6e074..4768f4f 100644
--- a/mediacopier-qt/source/worker.cpp
+++ b/mediacopier-qt/source/worker.cpp
@@ -23,11 +23,8 @@
 #include <mediacopier/file_info_factory.hpp>
 #include <mediacopier/file_register.hpp>
 
-#include <mediacopier/operation_copy.hpp>
 #include <mediacopier/operation_copy_jpeg.hpp>
-#include <mediacopier/operation_move.hpp>
 #include <mediacopier/operation_move_jpeg.hpp>
-#include <mediacopier/operation_simulate.hpp>
 
 #include <range/v3/view/filter.hpp>
 #include <range/v3/view/transform.hpp>
@@ -52,7 +49,7 @@ static volatile std::atomic<bool> operationSuspended(false);
 
 static constexpr const unsigned int DEFAULT_WAIT_MS = 200;
 
-auto check_operation_state()
+auto is_operation_cancelled()
 {
     while (true) {
         if (operationCancelled.load()) {
@@ -100,14 +97,6 @@ auto execute(const fs::path& dest, mc::FileInfoPtr file) -> void
 
 typedef void (*ExecFuncPtr)(const fs::path&, mc::FileInfoPtr);
 
-static const std::map<Config::Command, ExecFuncPtr> execFuncMap = {
-    {Config::Command::COPY, &execute<mc::FileOperationCopy>},
-    {Config::Command::COPY_JPEG, &execute<mc::FileOperationCopyJpeg>},
-    {Config::Command::MOVE, &execute<mc::FileOperationMove>},
-    {Config::Command::MOVE_JPEG, &execute<mc::FileOperationMoveJpeg>},
-    {Config::Command::SIMULATE, &execute<mc::FileOperationSimulate>}
-};
-
 } // namespace
 
 Worker::Worker(Config config) : m_config{std::move(config)}
@@ -174,37 +163,45 @@ void Worker::exec()
     m_fileCount = valid_media_file_count(m_config.inputDir());
     m_progress = 0;
 
-    auto reg = mc::FileRegister{m_config.outputDir(), m_config.pattern()};
-    auto execute = execFuncMap.at(m_config.command());
-    std::optional<fs::path> dest;
+    auto fileRegister = mc::FileRegister{m_config.outputDir(), m_config.pattern()};
 
-    try {
-        for (auto file : valid_media_files(m_config.inputDir())) {
-            if (check_operation_state()) {
-                spdlog::info("Operation was cancelled..");
-                break;
-            }
-            ++m_progress;
-            if ((dest = reg.add(file)).has_value()) {
+    ExecFuncPtr execute;
+    switch (m_config.command()) {
+    case Config::Command::COPY:
+        execute = &::execute<mc::FileOperationCopyJpeg>;
+        break;
+    case Config::Command::MOVE:
+        execute = &::execute<mc::FileOperationMoveJpeg>;
+        break;
+    }
+
+    std::optional<fs::path> dest;
+    for (auto file : valid_media_files(m_config.inputDir())) {
+        if (is_operation_cancelled()) {
+            spdlog::info("Operation was cancelled..");
+            break;
+        }
+        ++m_progress;
+        try {
+            if ((dest = fileRegister.add(file)).has_value()) {
                 Q_EMIT status({m_config.command(), file->path(), dest.value(), m_fileCount, m_progress});
                 execute(dest.value(), file);
             } else {
                 Q_EMIT status({m_config.command(), file->path(), "", m_fileCount, m_progress});
             }
+        } catch (const std::exception& err) {
+            spdlog::error(err.what());
         }
-    } catch (const std::exception& err) {
-        spdlog::error(err.what());
     }
 
-    spdlog::info("Removing duplicates..");
-    reg.removeDuplicates();
+    spdlog::info("Removing duplicates in destination directory..");
+    fileRegister.removeDuplicates();
 
     spdlog::info("Writing config..");
     m_config.writeConfigFile();
 
-    std::signal(SIGINT, SIG_DFL);
-
     spdlog::info("Done");
+    std::signal(SIGINT, SIG_DFL);
     Q_EMIT execDone();
 }