diff --git a/build.ninja b/build.ninja
new file mode 100644
index 0000000..0d2507b
--- /dev/null
+++ b/build.ninja
@@ -0,0 +1,16 @@
+rule cxx
+  command = g++ -c -o $out $in
+  description = CXX $out
+
+rule link
+  command = g++ -o $out $in
+  description = LINK $out
+
+build build/package.o: cxx src/package.cpp | src/package.h
+build build/command.o: cxx src/command.cpp | src/command.h build/package.o
+
+build build/main.o: cxx src/main.cpp
+
+build build/slackbuilder: link build/main.o build/command.o build/package.o
+
+default build/slackbuilder
diff --git a/src/command.cpp b/src/command.cpp
new file mode 100644
index 0000000..4066c23
--- /dev/null
+++ b/src/command.cpp
@@ -0,0 +1,74 @@
+#include "command.h"
+#include <cassert>
+
+namespace katja
+{
+    void list::execute() const
+    {
+        for (const auto& package : katja::read_package_database())
+        {
+            std::cout << package.second.name()
+                << " " << package.second.version()
+                << " (" << package.second.tag() << ")"
+                << std::endl;
+        }
+    }
+
+    void help::execute() const
+    {
+        std::cout << "Usage:\n"
+            "\tkatja {info|help} [OPTIONS]\n\n";
+    }
+
+    command_exception::command_exception(const command_exception_t exception_type,
+        std::vector<std::string> failed_arguments) noexcept
+        : m_exception_type(exception_type), m_failed_arguments(failed_arguments)
+    {
+    }
+
+    const char *command_exception::what() const noexcept
+    {
+        switch (m_exception_type)
+        {
+            case command_exception_t::no_command:
+                return "No command specified.";
+            case command_exception_t::too_many_arguments:
+                return "Too many arguments given.";
+            case command_exception_t::unknown_command:
+                return "Unknown command.";
+        }
+        assert(false);
+    }
+
+    const std::vector<std::string>& command_exception::failed_arguments() const noexcept
+    {
+        return m_failed_arguments;
+    }
+
+    std::unique_ptr<command> parse_command_line(int argc, char **argv)
+    {
+        if (argc > 2)
+        {
+            std::vector<std::string> failed_arguments;
+
+            for (std::size_t i = 2; i < argc; ++i)
+            {
+                failed_arguments.push_back(argv[i]);
+            }
+            throw command_exception(command_exception_t::unknown_command);
+        }
+        else if (argc < 2)
+        {
+            throw command_exception(command_exception_t::no_command);
+        }
+        if (strcmp(argv[1], "list") == 0)
+        {
+            return std::make_unique<list>();
+        }
+        else if (strcmp(argv[1], "help") == 0)
+        {
+            return std::make_unique<help>();
+        }
+        throw command_exception(command_exception_t::unknown_command, { argv[1] });
+    }
+}
diff --git a/src/command.h b/src/command.h
new file mode 100644
index 0000000..8d0679d
--- /dev/null
+++ b/src/command.h
@@ -0,0 +1,48 @@
+#include <iostream>
+#include <cstring>
+#include <memory>
+#include <vector>
+#include "package.h"
+
+namespace katja
+{
+    class command
+    {
+    public:
+        virtual void execute() const = 0;
+    };
+
+    class list final : public command
+    {
+    public:
+        void execute() const override;
+    };
+
+    class help final : public command
+    {
+    public:
+        void execute() const override;
+    };
+
+    enum class command_exception_t
+    {
+        no_command,
+        too_many_arguments,
+        unknown_command,
+    };
+
+    class command_exception final : public std::exception
+    {
+        command_exception_t m_exception_type;
+        std::vector<std::string> m_failed_arguments;
+
+    public:
+        explicit command_exception(const command_exception_t exception_type,
+            std::vector<std::string> failed_arguments = {}) noexcept;
+
+        const char *what() const noexcept override;
+        const std::vector<std::string>& failed_arguments() const noexcept;
+    };
+
+    std::unique_ptr<command> parse_command_line(int argc, char **argv);
+}
diff --git a/src/main.cpp b/src/main.cpp
new file mode 100644
index 0000000..ef8dfcd
--- /dev/null
+++ b/src/main.cpp
@@ -0,0 +1,22 @@
+#include "command.h"
+
+int main(int argc, char **argv)
+{
+    std::unique_ptr<katja::command> command;
+
+    try
+    {
+        command = katja::parse_command_line(argc, argv);
+    }
+    catch (katja::command_exception& e)
+    {
+        std::cout << e.what() << std::endl << std::endl;
+
+        katja::help().execute();
+
+        return EXIT_FAILURE;
+    }
+    command->execute();
+
+    return EXIT_SUCCESS;
+}
diff --git a/src/package.cpp b/src/package.cpp
new file mode 100644
index 0000000..0734a5e
--- /dev/null
+++ b/src/package.cpp
@@ -0,0 +1,76 @@
+#include "package.h"
+#include <filesystem>
+
+namespace katja
+{
+    package::package(const std::string& name, const std::string& version,
+        const std::string& architecture, const std::string& tag)
+        : m_name(name), m_version(version), m_architecture(architecture), m_tag(tag)
+    {
+    }
+
+    const std::string& package::name() const noexcept
+    {
+        return m_name;
+    }
+
+    const std::string& package::version() const noexcept
+    {
+        return m_version;
+    }
+
+    const std::string& package::architecture() const noexcept
+    {
+        return m_architecture;
+    }
+
+    const std::string& package::tag() const noexcept
+    {
+        return m_tag;
+    }
+
+    std::optional<package> package::parse(const std::string& full_name) noexcept
+    {
+        std::size_t tag_separator = full_name.find_last_of('-');
+
+        if (tag_separator == std::string::npos || tag_separator == 0)
+        {
+            return std::nullopt;
+        }
+        std::size_t architecture_separator = full_name.find_last_of('-', tag_separator - 1);
+
+        if (architecture_separator == std::string::npos || architecture_separator == 0)
+        {
+            return std::nullopt;
+        }
+        std::size_t version_separator = full_name.find_last_of('-', architecture_separator - 1);
+
+        if (version_separator == std::string::npos || version_separator == 0)
+        {
+            return std::nullopt;
+        }
+        package parsed_package{
+            full_name.substr(0, version_separator),
+            full_name.substr(version_separator + 1, architecture_separator - version_separator - 1),
+            full_name.substr(architecture_separator + 1, tag_separator - architecture_separator - 1),
+            full_name.substr(tag_separator + 1)
+        };
+        return std::make_optional(parsed_package);
+    }
+
+    std::unordered_map<std::string, package> read_package_database()
+    {
+        std::unordered_map<std::string, package> packages;
+
+        for (const auto& entry : std::filesystem::directory_iterator("/var/lib/pkgtools/packages"))
+        {
+            std::optional<package> maybe_package = package::parse(entry.path().filename());
+
+            if (maybe_package.has_value())
+            {
+                packages.insert_or_assign(maybe_package.value().name(), maybe_package.value());
+            }
+        }
+        return packages;
+    }
+}
diff --git a/src/package.h b/src/package.h
new file mode 100644
index 0000000..5ffd060
--- /dev/null
+++ b/src/package.h
@@ -0,0 +1,27 @@
+#include <string>
+#include <optional>
+#include <unordered_map>
+
+namespace katja
+{
+    class package
+    {
+        std::string m_name;
+        std::string m_version;
+        std::string m_architecture;
+        std::string m_tag;
+
+    public:
+        explicit package(const std::string& name, const std::string& version,
+            const std::string& architecture, const std::string& tag);
+
+        const std::string& name() const noexcept;
+        const std::string& version() const noexcept;
+        const std::string& architecture() const noexcept;
+        const std::string& tag() const noexcept;
+
+        static std::optional<package> parse(const std::string& full_name) noexcept;
+    };
+
+    std::unordered_map<std::string, package> read_package_database();
+}
diff --git a/test.sh b/test.sh
deleted file mode 100755
index c436583..0000000
--- a/test.sh
+++ /dev/null
@@ -1,4 +0,0 @@
-#!/bin/sh
-
-bundle install
-bundle exec rubocop