diff --git a/Cargo.lock b/Cargo.lock
index f695e4e..8eaeb05 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -172,6 +172,56 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "anstream"
+version = "0.6.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "43d5b281e737544384e969a5ccad3f1cdd24b48086a0fc1b2a5262a26b8f4f4a"
+dependencies = [
+ "anstyle",
+ "anstyle-parse",
+ "anstyle-query",
+ "anstyle-wincon",
+ "colorchoice",
+ "is_terminal_polyfill",
+ "utf8parse",
+]
+
+[[package]]
+name = "anstyle"
+version = "1.0.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5192cca8006f1fd4f7237516f40fa183bb07f8fbdfedaa0036de5ea9b0b45e78"
+
+[[package]]
+name = "anstyle-parse"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4e7644824f0aa2c7b9384579234ef10eb7efb6a0deb83f9630a49594dd9c15c2"
+dependencies = [
+ "utf8parse",
+]
+
+[[package]]
+name = "anstyle-query"
+version = "1.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "40c48f72fd53cd289104fc64099abca73db4166ad86ea0b4341abe65af83dadc"
+dependencies = [
+ "windows-sys 0.61.2",
+]
+
+[[package]]
+name = "anstyle-wincon"
+version = "3.0.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "291e6a250ff86cd4a820112fb8898808a366d8f9f58ce16d1f538353ad55747d"
+dependencies = [
+ "anstyle",
+ "once_cell_polyfill",
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "arboard"
 version = "3.6.1"
@@ -674,6 +724,46 @@ dependencies = [
  "windows-link",
 ]
 
+[[package]]
+name = "clap"
+version = "4.5.54"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c6e6ff9dcd79cff5cd969a17a545d79e84ab086e444102a591e288a8aa3ce394"
+dependencies = [
+ "clap_builder",
+ "clap_derive",
+]
+
+[[package]]
+name = "clap_builder"
+version = "4.5.54"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fa42cf4d2b7a41bc8f663a7cab4031ebafa1bf3875705bfaf8466dc60ab52c00"
+dependencies = [
+ "anstream",
+ "anstyle",
+ "clap_lex",
+ "strsim",
+]
+
+[[package]]
+name = "clap_derive"
+version = "4.5.49"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2a0b5487afeab2deb2ff4e03a807ad1a03ac532ff5a2cee5d86884440c7f7671"
+dependencies = [
+ "heck",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.111",
+]
+
+[[package]]
+name = "clap_lex"
+version = "0.7.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1d728cc89cf3aee9ff92b05e62b19ee65a02b5702cff7d5a377e32c6ae29d8d"
+
 [[package]]
 name = "clipboard-win"
 version = "5.4.1"
@@ -693,6 +783,12 @@ dependencies = [
  "unicode-width",
 ]
 
+[[package]]
+name = "colorchoice"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b05b61dc5112cbb17e4b6cd61790d9845d13888356391624cbe7e41efeac1e75"
+
 [[package]]
 name = "com"
 version = "0.6.0"
@@ -1515,6 +1611,12 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "heck"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2304e00983f87ffb38b55b444b5e3b60a884b5d30c0fca7d82fe33449bbe55ea"
+
 [[package]]
 name = "hermit-abi"
 version = "0.5.2"
@@ -1691,6 +1793,12 @@ dependencies = [
  "hashbrown 0.16.1",
 ]
 
+[[package]]
+name = "is_terminal_polyfill"
+version = "1.70.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a6cb138bb79a146c1bd460005623e142ef0181e3d0219cb493e02f7d08a35695"
+
 [[package]]
 name = "itoa"
 version = "1.0.15"
@@ -2300,6 +2408,12 @@ version = "1.21.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "42f5e15c9953c5e4ccceeb2e7382a716482c34515315f7b03532b8b4e8393d2d"
 
+[[package]]
+name = "once_cell_polyfill"
+version = "1.70.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "384b8ab6d37215f3c5301a95a4accb5d64aa607f1fcb26a11b5303878451b4fe"
+
 [[package]]
 name = "orbclient"
 version = "0.3.49"
@@ -2706,9 +2820,10 @@ dependencies = [
 
 [[package]]
 name = "rlogg"
-version = "0.3.1"
+version = "0.4.0"
 dependencies = [
  "chrono",
+ "clap",
  "eframe",
  "rayon",
  "regex",
@@ -3007,6 +3122,12 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6637bab7722d379c8b41ba849228d680cc12d0a45ba1fa2b48f2a30577a06731"
 
+[[package]]
+name = "strsim"
+version = "0.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
+
 [[package]]
 name = "syn"
 version = "1.0.109"
@@ -3279,6 +3400,12 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b6c140620e7ffbb22c2dee59cafe6084a59b5ffc27a8859a5f0d494b5d52b6be"
 
+[[package]]
+name = "utf8parse"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
+
 [[package]]
 name = "uuid"
 version = "1.18.1"
diff --git a/Cargo.toml b/Cargo.toml
index 07224a6..7add6a7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "rlogg"
-version = "0.3.1"
+version = "0.4.0"
 edition = "2024"
 authors = ["Stanislav Pastushenko <staspast1@gmail.com>"]
 description = "A fast log file viewer with search, filtering, and highlighting capabilities"
@@ -18,6 +18,7 @@ serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 rayon = "1.10"
 chrono = "0.4"
+clap = { version = "4.5", features = ["derive"] }
 
 [profile.release]
 debug = false
\ No newline at end of file
diff --git a/README.md b/README.md
index 116be24..e23c1fb 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,247 @@
-# rlogg
+# RLogg - Fast Log File Viewer
 
-A fast log file viewer with search, filtering, and highlighting capabilities
\ No newline at end of file
+A fast, native log file viewer with search, filtering, and highlighting capabilities built with Rust and egui.
+
+## Features
+
+- **Fast Performance**: Handle large log files (GB+) with efficient line indexing
+- **Advanced Search**: Regex support, case-sensitive/insensitive search, date range filtering
+- **Syntax Highlighting**: Custom highlight rules with regex patterns
+- **Multiple Tabs**: Open and view multiple log files simultaneously
+- **Export Results**: Export filtered/searched results to new files
+- **Cross-Platform**: Native builds for Linux, Windows, and macOS
+- **Command-Line Interface**: Open files directly from terminal or OS file associations
+
+## Installation
+
+### From Source
+
+1. **Clone the repository:**
+   ```bash
+   git clone https://github.com/yourusername/rlogg.git
+   cd rlogg
+   ```
+
+2. **Build in release mode:**
+   ```bash
+   cargo build --release
+   ```
+
+3. **The binary will be available at:**
+   ```
+   target/release/rlogg
+   ```
+
+### Linux
+
+#### Quick Install (User-Local)
+
+```bash
+cargo build --release
+cd packaging/linux
+./install.sh
+```
+
+This will:
+- Install `rlogg` to `~/.local/bin/`
+- Set up file associations for `.log` files
+- Configure desktop integration
+
+Make sure `~/.local/bin` is in your PATH:
+```bash
+export PATH="$HOME/.local/bin:$PATH"
+```
+
+#### System-Wide Install
+
+```bash
+sudo cp target/release/rlogg /usr/local/bin/
+sudo cp packaging/linux/rlogg.desktop /usr/share/applications/
+sudo cp packaging/linux/text-x-log.xml /usr/share/mime/packages/
+sudo update-desktop-database /usr/share/applications
+sudo update-mime-database /usr/share/mime
+```
+
+### Windows
+
+1. **Build the project:**
+   ```powershell
+   cargo build --release
+   ```
+
+2. **Run the installation script:**
+   ```powershell
+   cd packaging\windows
+   powershell -ExecutionPolicy Bypass -File install.ps1
+   ```
+
+This will:
+- Install RLogg to `%LOCALAPPDATA%\Programs\RLogg`
+- Create file associations for `.log` files
+- Add "Open with RLogg" to the context menu
+
+## Usage
+
+### Graphical Interface
+
+**Launch without arguments:**
+```bash
+rlogg
+```
+
+Then use the "Open File" button to select log files.
+
+### Command-Line Interface
+
+**Open a single file:**
+```bash
+rlogg /path/to/file.log
+```
+
+**Open multiple files (each in a separate tab):**
+```bash
+rlogg file1.log file2.log file3.log
+```
+
+**Open all log files in a directory:**
+```bash
+rlogg /var/log/*.log
+```
+
+**Get help:**
+```bash
+rlogg --help
+```
+
+**Check version:**
+```bash
+rlogg --version
+```
+
+### File Associations
+
+After installation, you can:
+- **Double-click** `.log` files to open them in RLogg
+- **Right-click** → "Open With" → RLogg
+- **Drag and drop** multiple log files onto the RLogg icon
+
+See [docs/FILE_ASSOCIATIONS.md](docs/FILE_ASSOCIATIONS.md) for detailed setup and troubleshooting.
+
+## Features Guide
+
+### Search
+
+1. Enter search query in the search panel
+2. Choose case-sensitive or regex mode
+3. Optionally enable date range filtering
+4. Results are highlighted and filtered in real-time
+
+### Highlighting
+
+1. Click "Highlight Rules" to open the editor
+2. Add custom regex patterns with colors
+3. Rules are applied to all open files
+4. Perfect for highlighting errors, warnings, etc.
+
+### Tabs
+
+- Open multiple files simultaneously
+- Each file maintains its own search/filter state
+- Close tabs with the × button
+- Switch between tabs with mouse or keyboard
+
+### Export
+
+- Export filtered/searched results to a new file
+- Preserves line formatting
+- Useful for extracting specific log entries
+
+## Building
+
+### Prerequisites
+
+- Rust 1.70 or later
+- Cargo
+
+### Build Commands
+
+**Development build:**
+```bash
+cargo build
+```
+
+**Release build (optimized):**
+```bash
+cargo build --release
+```
+
+**Run directly:**
+```bash
+cargo run -- /path/to/file.log
+```
+
+**Run tests:**
+```bash
+cargo test
+```
+
+See [BUILD.md](BUILD.md) for detailed build instructions.
+
+## Packaging
+
+See [packaging/README.md](packaging/README.md) for instructions on creating distribution packages:
+- Linux: `.deb`, `.rpm`, AppImage, tarballs
+- Windows: Installers, ZIP archives
+
+## Configuration
+
+RLogg stores configuration in `rlogg_config.json` next to the executable:
+- Search history
+- Highlight rules
+- UI preferences
+- Date format settings
+
+## Troubleshooting
+
+### Linux
+
+**File associations not working:**
+```bash
+update-desktop-database ~/.local/share/applications
+update-mime-database ~/.local/share/mime
+```
+
+**Binary not found:**
+Ensure `~/.local/bin` is in your PATH.
+
+### Windows
+
+**File associations not working:**
+1. Restart File Explorer
+2. Check registry entries (see [docs/FILE_ASSOCIATIONS.md](docs/FILE_ASSOCIATIONS.md))
+
+**Permission errors:**
+Run PowerShell as Administrator or install to user directory.
+
+For more troubleshooting, see [docs/FILE_ASSOCIATIONS.md](docs/FILE_ASSOCIATIONS.md).
+
+## Contributing
+
+Contributions are welcome! Please:
+1. Fork the repository
+2. Create a feature branch
+3. Make your changes
+4. Run tests and formatting
+5. Submit a pull request
+
+## License
+
+MIT OR Apache-2.0
+
+## Acknowledgments
+
+Built with:
+- [eframe](https://github.com/emilk/egui/tree/master/crates/eframe) - GUI framework
+- [egui](https://github.com/emilk/egui) - Immediate mode GUI library
+- [rfd](https://github.com/PolyMeilex/rfd) - Native file dialogs
+- [clap](https://github.com/clap-rs/clap) - Command-line argument parsing
\ No newline at end of file
diff --git a/src/log_viewer_app.rs b/src/log_viewer_app.rs
index d6794fa..4642bd6 100644
--- a/src/log_viewer_app.rs
+++ b/src/log_viewer_app.rs
@@ -1,10 +1,11 @@
 use std::sync::Arc;
+use std::path::PathBuf;
 use eframe::egui;
 use crate::config::AppConfig;
 use crate::file_tab::FileTab;
 use crate::highlight::HighlightManager;
 use crate::search::{add_to_history, start_search, SearchParams, SearchState};
-use crate::tab_manager::{close_tab, open_file_dialog, IndexingState};
+use crate::tab_manager::{close_tab, open_file, open_file_dialog, IndexingState};
 use crate::ui::{render_highlight_editor, render_search_panel, render_tabs_panel, render_top_menu, SearchPanelState};
 use crate::ui::log_panel::{render_filter_panel, render_main_log_panel};
 
@@ -16,6 +17,7 @@ pub struct LogViewerApp {
     search_state: SearchState,
     highlight_manager: HighlightManager,
     first_frame: bool,
+    file_open_errors: Vec<String>,
 }
 
 struct KeyAction {
@@ -34,9 +36,30 @@ impl KeyAction {
 }
 
 impl LogViewerApp {
-    pub fn new(config: AppConfig) -> Self {
+    pub fn new(config: AppConfig, initial_files: Vec<PathBuf>) -> Self {
+        let indexing_state = IndexingState::new();
+        let mut tabs = Vec::new();
+        let mut file_open_errors = Vec::new();
+
+        // Open initial files from command line
+        for file_path in initial_files {
+            if file_path.exists() {
+                if file_path.is_file() {
+                    if let Some(tab) = open_file(file_path.clone(), &indexing_state) {
+                        tabs.push(tab);
+                    } else {
+                        file_open_errors.push(format!("Failed to open: {}", file_path.display()));
+                    }
+                } else {
+                    file_open_errors.push(format!("Not a file: {}", file_path.display()));
+                }
+            } else {
+                file_open_errors.push(format!("File not found: {}", file_path.display()));
+            }
+        }
+
         Self {
-            tabs: Vec::new(),
+            tabs,
             active_tab_index: 0,
             search_panel_state: SearchPanelState {
                 query: config.last_search_query,
@@ -48,10 +71,11 @@ impl LogViewerApp {
                 date_from: config.date_from,
                 date_to: config.date_to,
             },
-            indexing_state: IndexingState::new(),
+            indexing_state,
             search_state: SearchState::new(),
             highlight_manager: HighlightManager::new(config.highlight_rules),
             first_frame: true,
+            file_open_errors,
         }
     }
 
@@ -246,6 +270,32 @@ impl LogViewerApp {
             self.first_frame = false;
             ctx.send_viewport_cmd(egui::ViewportCommand::Maximized(true));
         }
+
+        // Display file opening errors if any
+        if !self.file_open_errors.is_empty() {
+            egui::Window::new("File Opening Errors")
+                .collapsible(false)
+                .resizable(false)
+                .anchor(egui::Align2::CENTER_CENTER, [0.0, 0.0])
+                .show(ctx, |ui| {
+                    ui.label("The following files could not be opened:");
+                    ui.add_space(10.0);
+
+                    egui::ScrollArea::vertical()
+                        .max_height(300.0)
+                        .show(ui, |ui| {
+                            for error in &self.file_open_errors {
+                                ui.label(error);
+                            }
+                        });
+
+                    ui.add_space(10.0);
+
+                    if ui.button("OK").clicked() {
+                        self.file_open_errors.clear();
+                    }
+                });
+        }
     }
 }
 
diff --git a/src/main.rs b/src/main.rs
index c89fc9e..98a132e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -13,11 +13,25 @@ mod ui;
 mod log_viewer_app;
 
 use eframe::egui;
+use clap::Parser;
+use std::path::PathBuf;
 
 use crate::log_viewer_app::LogViewerApp;
 use config::AppConfig;
 
+#[derive(Parser)]
+#[command(name = "rlogg")]
+#[command(version, about = "A fast log file viewer with search, filtering, and highlighting")]
+struct Cli {
+    /// Log files to open on startup
+    #[arg(value_name = "FILES")]
+    files: Vec<PathBuf>,
+}
+
 fn main() -> eframe::Result {
+    // Parse command-line arguments
+    let cli = Cli::parse();
+
     let options = eframe::NativeOptions {
         viewport: egui::ViewportBuilder::default()
             .with_inner_size([1200.0, 800.0])
@@ -28,13 +42,14 @@ fn main() -> eframe::Result {
     };
 
     let config = AppConfig::load();
+    let initial_files = cli.files;
 
     eframe::run_native(
         "RLogg",
         options,
         Box::new(move |cc| {
             theme::apply_theme(&cc.egui_ctx);
-            Ok(Box::new(LogViewerApp::new(config)))
+            Ok(Box::new(LogViewerApp::new(config, initial_files)))
         }),
     )
 }
diff --git a/src/tab_manager.rs b/src/tab_manager.rs
index 012ea61..8af8ebc 100644
--- a/src/tab_manager.rs
+++ b/src/tab_manager.rs
@@ -42,7 +42,7 @@ pub fn open_file_dialog(indexing_state: &IndexingState) -> Option<FileTab> {
     open_file(path, indexing_state)
 }
 
-fn open_file(path: PathBuf, indexing_state: &IndexingState) -> Option<FileTab> {
+pub fn open_file(path: PathBuf, indexing_state: &IndexingState) -> Option<FileTab> {
     indexing_state.start_indexing();
 
     // Background indexing for progress indication