diff --git a/exasol/exaslpm/model/package_file_config.py b/exasol/exaslpm/model/package_file_config.py
index b09be9e..431306e 100644
--- a/exasol/exaslpm/model/package_file_config.py
+++ b/exasol/exaslpm/model/package_file_config.py
@@ -1,8 +1,3 @@
-import pathlib
-from enum import Enum
-from pathlib import Path
-from typing import List
-
 from pydantic import (
     BaseModel,
     field_validator,
diff --git a/exasol/exaslpm/pkg_mgmt/cmd_executor.py b/exasol/exaslpm/pkg_mgmt/cmd_executor.py
new file mode 100644
index 0000000..7054777
--- /dev/null
+++ b/exasol/exaslpm/pkg_mgmt/cmd_executor.py
@@ -0,0 +1,100 @@
+import subprocess
+import sys
+from collections.abc import (
+    Callable,
+    Iterator,
+)
+from typing import Protocol
+
+
+class CommandLogger(Protocol):
+    def info(self, msg: str) -> None: ...
+    def warn(self, msg: str) -> None: ...
+    def error(self, msg: str) -> None: ...
+
+
+class StdLogger:
+    def info(self, msg: str) -> None:
+        self._last_msg = msg
+        sys.stdout.write(msg)
+
+    def warn(self, msg: str) -> None:
+        self._last_msg = msg
+        sys.stderr.write(msg)
+
+    def error(self, msg: str) -> None:
+        self._last_msg = msg
+        sys.stderr.write(msg)
+
+    def get_last_msg(self) -> str:
+        return self._last_msg
+
+
+class CommandResult:
+    def __init__(
+        self,
+        logger: CommandLogger,
+        fn_ret_code: Callable[[], int],
+        stdout: Iterator[str],
+        stderr: Iterator[str],
+    ):
+        self._log = logger
+        self._fn_return_code = fn_ret_code  # a lambda to subprocess.open.wait
+        self._stdout = stdout
+        self._stderr = stderr
+
+    def return_code(self):
+        return self._fn_return_code()
+
+    def itr_stdout(self) -> Iterator[str]:
+        return self._stdout
+
+    def itr_stderr(self) -> Iterator[str]:
+        return self._stderr
+
+    def consume_results(
+        self,
+        consume_stdout: Callable[[str | bytes], None],
+        consume_stderr: Callable[[str | bytes], None],
+    ):
+
+        def pick_next(out_stream, callback) -> bool:
+            try:
+                _val = next(out_stream)
+                callback(_val)
+            except StopIteration:
+                return False
+            return True
+
+        # Read from _stdout and _stderr simultaneously
+        stdout_continue = True
+        stderr_continue = True
+        while stdout_continue or stderr_continue:
+            if stdout_continue:
+                stdout_continue = pick_next(self._stdout, consume_stdout)
+            if stderr_continue:
+                stderr_continue = pick_next(self._stderr, consume_stderr)
+        return self.return_code()
+
+    def print_results(self):
+        ret_code = self.consume_results(self._log.info, self._log.error)
+        self._log.info(f"Return Code: {ret_code}")
+
+
+class CommandExecutor:
+    def __init__(self, logger: CommandLogger):
+        self._log = logger
+
+    def execute(self, cmd_strs: list[str]) -> CommandResult:
+        cmd_str = " ".join(cmd_strs)
+        self._log.info(f"Executing: {cmd_str}")
+
+        sub_process = subprocess.Popen(
+            cmd_strs, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True
+        )
+        return CommandResult(
+            self._log,
+            fn_ret_code=lambda: sub_process.wait(),
+            stdout=iter(sub_process.stdout),
+            stderr=iter(sub_process.stderr),
+        )
diff --git a/exasol/exaslpm/pkg_mgmt/install_apt.py b/exasol/exaslpm/pkg_mgmt/install_apt.py
new file mode 100644
index 0000000..156bef6
--- /dev/null
+++ b/exasol/exaslpm/pkg_mgmt/install_apt.py
@@ -0,0 +1,69 @@
+from exasol.exaslpm.model.package_file_config import AptPackages
+from exasol.exaslpm.pkg_mgmt.cmd_executor import (
+    CommandExecutor,
+    CommandLogger,
+)
+
+
+def prepare_update_command() -> list[str]:
+    update_cmd = ["apt-get", "-y", "update"]
+    return update_cmd
+
+
+def prepare_clean_cmd() -> list[str]:
+    clean_cmd = ["apt-get", "-y", "clean"]
+    return clean_cmd
+
+
+def prepare_autoremove_cmd() -> list[str]:
+    autoremove_cmd = ["apt-get", "-y", "autoremove"]
+    return autoremove_cmd
+
+
+def prepare_ldconfig_cmd() -> list[str]:
+    ldconfig_cmd = ["ldconfig"]
+    return ldconfig_cmd
+
+
+def prepare_locale_cmd() -> list[str]:
+    locale_cmd = ["locale-gen", "&&", "update-locale", "LANG=en_US.UTF8"]
+    return locale_cmd
+
+
+def prepare_install_cmd(apt_packages: AptPackages) -> list[str]:
+    install_cmd = ["apt-get", "install", "-V", "-y", "--no-install-recommends"]
+    if apt_packages.packages is not None:
+        for package in apt_packages.packages:
+            install_cmd.append(f"{package.name}={package.version}")
+    return install_cmd
+
+
+def install_via_apt(
+    apt_packages: AptPackages, executor: CommandExecutor, log: CommandLogger
+):
+    if len(apt_packages.packages) > 0:
+        update_cmd = prepare_update_command()
+        cmd_res = executor.execute(update_cmd)
+        cmd_res.print_results()
+
+        install_cmd = prepare_install_cmd(apt_packages)
+        cmd_res = executor.execute(install_cmd)
+        cmd_res.print_results()
+
+        clean_cmd = prepare_clean_cmd()
+        cmd_res = executor.execute(clean_cmd)
+        cmd_res.print_results()
+
+        autoremove_cmd = prepare_autoremove_cmd()
+        cmd_res = executor.execute(autoremove_cmd)
+        cmd_res.print_results()
+
+        locale_cmd = prepare_locale_cmd()
+        cmd_res = executor.execute(locale_cmd)
+        cmd_res.print_results()
+
+        ldconfig_cmd = prepare_ldconfig_cmd()
+        cmd_res = executor.execute(ldconfig_cmd)
+        cmd_res.print_results()
+    else:
+        log.error("Got an empty list of AptPackages")
diff --git a/exasol/exaslpm/pkg_mgmt/install_packages.py b/exasol/exaslpm/pkg_mgmt/install_packages.py
index dccaea7..c241620 100644
--- a/exasol/exaslpm/pkg_mgmt/install_packages.py
+++ b/exasol/exaslpm/pkg_mgmt/install_packages.py
@@ -1,6 +1,26 @@
 import pathlib
 
-import click
+import yaml
+
+from exasol.exaslpm.model.package_file_config import (
+    PackageFile,
+    Phase,
+)
+from exasol.exaslpm.pkg_mgmt.cmd_executor import (
+    CommandExecutor,
+    StdLogger,
+)
+from exasol.exaslpm.pkg_mgmt.install_apt import install_via_apt
+
+
+def parse_package_file(
+    package_file: PackageFile, phase_name: str, build_step_name: str
+) -> Phase:
+    build_steps = package_file.build_steps
+    build_step = build_steps[build_step_name]
+    phases = build_step.phases
+    phase = phases[phase_name]
+    return phase
 
 
 def package_install(
@@ -11,6 +31,7 @@ def package_install(
     conda_binary: pathlib.Path,
     r_binary: pathlib.Path,
 ):
+    """
     click.echo(
         f"Phase: {phase}, \
         Package File: {package_file}, \
@@ -19,6 +40,15 @@ def package_install(
         Conda Binary: {conda_binary}, \
         R Binary: {r_binary}",
     )
+    """
 
     package_content = package_file.read_text()
-    click.echo(package_content)
+    try:
+        logger = StdLogger()
+        yaml_data = yaml.safe_load(package_content)
+        pkg_file = PackageFile.model_validate(yaml_data)
+        single_phase = parse_package_file(pkg_file, phase, build_step)
+        if single_phase.apt is not None:
+            install_via_apt(single_phase.apt, CommandExecutor(logger), logger)
+    except ValueError:
+        print("Error parsing package file")
diff --git a/poetry.lock b/poetry.lock
index f38ac43..50cd84c 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1,4 +1,4 @@
-# This file is automatically @generated by Poetry 2.1.3 and should not be changed by hand.
+# This file is automatically @generated by Poetry 2.2.1 and should not be changed by hand.
 
 [[package]]
 name = "accessible-pygments"
@@ -2008,7 +2008,7 @@ version = "6.0.3"
 description = "YAML parser and emitter for Python"
 optional = false
 python-versions = ">=3.8"
-groups = ["dev"]
+groups = ["main", "dev"]
 files = [
     {file = "PyYAML-6.0.3-cp38-cp38-macosx_10_13_x86_64.whl", hash = "sha256:c2514fceb77bc5e7a2f7adfaa1feb2fb311607c9cb518dbc378688ec73d8292f"},
     {file = "PyYAML-6.0.3-cp38-cp38-manylinux2014_aarch64.manylinux_2_17_aarch64.manylinux_2_28_aarch64.whl", hash = "sha256:9c57bb8c96f6d1808c030b1687b9b5fb476abaa47f0db9c0101f5e9f394e97f4"},
@@ -2663,4 +2663,4 @@ files = [
 [metadata]
 lock-version = "2.1"
 python-versions = ">=3.10,<3.15"
-content-hash = "68951365dc4d5c4a8047c692904943526862853504579e50d98fb7d07fd2a17b"
+content-hash = "c4f669f8777ccba8c3136782d5c0ac109b3d569de2e814d3fd47f31da1c39270"
diff --git a/pyproject.toml b/pyproject.toml
index 44ced0f..1ff37d7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -24,6 +24,7 @@ homepage = "https://github.com/exasol/script-languages-package-management"
 [tool.poetry.dependencies]
 click = ">=8.3.0, <9.0.0"
 pydantic="^2.10.2"
+pyyaml = "^6.0.3"
 
 [tool.poetry.group.dev.dependencies]
 exasol-toolbox = ">=1.6.0, <2.0.0"
@@ -31,6 +32,9 @@ pyinstaller = ">=6.15.0, <7.0.0"
 types-pyinstaller = ">=6.15.0.20250822, <7.0.0.0"
 docker = { version = ">=7.1.0,<8.0.0", markers = "sys_platform != 'win32'" }
 
+[tool.poetry.scripts]
+exaslpm = 'exasol.exaslpm.main:main'
+
 [build-system]
 requires = ["poetry-core>=2.0.0"]
 build-backend = "poetry.core.masonry.api"
diff --git a/test/resources/package_file_01.yaml b/test/resources/package_file_01.yaml
new file mode 100644
index 0000000..2e0a97c
--- /dev/null
+++ b/test/resources/package_file_01.yaml
@@ -0,0 +1,71 @@
+# Top-level comment about the package file
+comment: "Main package file for build steps"
+
+build_steps:
+  build_step_1:
+    comment: "First build step, e.g., system dependencies"
+    phases:
+      phase_1:
+        comment: "APT packages for base system"
+        apt:
+          comment: "Comment for APT section"
+          packages:
+            - name: "curl"
+              version: "7.68.0"
+              comment: "For downloading"
+            - name: "git"
+              version: "2.25.1"
+              comment: "VCS support"
+        pip:
+          comment: "Python packages"
+          packages:
+            - name: "requests"
+              version: "2.31.0"
+              comment: "HTTP package"
+            - name: "click"
+              version: "8.1.7"
+              comment: "CLI utilities"
+        r:
+          comment: "Optional R packages"
+          packages:
+            - name: "ggplot2"
+              version: "3.4.0"
+              comment: "Plotting library"
+        conda:
+          comment: "Optional conda packages"
+          channels:
+            - "defaults"
+            - "conda-forge"
+          packages:
+            - name: "numpy"
+              version: "1.26.0"
+              comment: "NumPy for Python"
+            - name: "pandas"
+              version: "2.1.2"
+              comment: "Data manipulation"
+      phase_2:
+        comment: "Dev tools for CI/CD"
+        apt:
+          comment: "Additional apt packages"
+          packages:
+            - name: "python3"
+              version: "3.8.10"
+              comment: "System python"
+        # You can leave out pip/r/conda if not needed in this phase
+
+  build_step_2:
+    comment: "Second build step, e.g., App build"
+    phases:
+      phase_install:
+        comment: "Install app dependencies"
+        pip:
+          packages:
+            - name: "flask"
+              version: "3.0.0"
+              comment: "Web framework"
+            - name: "sqlalchemy"
+              version: "2.0.22"
+              comment: "ORM"
+        # APT/R/Conda can be omitted if not needed here
+
+# You can add further build_steps and phases as needed.
diff --git a/test/unit/pkg_mgmt/__init__.py b/test/unit/pkg_mgmt/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/test/unit/pkg_mgmt/test_apt_install.py b/test/unit/pkg_mgmt/test_apt_install.py
new file mode 100644
index 0000000..583abc9
--- /dev/null
+++ b/test/unit/pkg_mgmt/test_apt_install.py
@@ -0,0 +1,107 @@
+from unittest.mock import (
+    MagicMock,
+    Mock,
+    call,
+)
+
+import pytest
+
+from exasol.exaslpm.model.package_file_config import (
+    AptPackages,
+    Package,
+)
+from exasol.exaslpm.pkg_mgmt.cmd_executor import (
+    CommandExecutor,
+    CommandResult,
+    StdLogger,
+)
+from exasol.exaslpm.pkg_mgmt.install_apt import *
+
+order_of_exec = ["update", "install", "clean", "remove", "locale", "ldconfig"]
+call_count = 0
+
+
+def mock_execute(_, cmd_strs):
+    global call_count
+    cmd_str = " ".join(cmd_strs)
+    assert order_of_exec[call_count] in cmd_str
+    call_count += 1
+    return CommandResult(
+        StdLogger(), fn_ret_code=lambda: 0, stdout=iter([]), stderr=iter([])
+    )
+
+
+def test_install_via_apt_empty_packages(monkeypatch):
+    logger = StdLogger()
+    monkeypatch.setattr(CommandExecutor, "execute", mock_execute)
+    aptPackages = AptPackages(packages=[])
+    install_via_apt(aptPackages, CommandExecutor(logger), logger)
+    assert "empty list" in logger.get_last_msg()
+
+
+def test_install_via_apt_01():
+    mock_executor = MagicMock(spec=CommandExecutor)
+    pkgs = [
+        Package(name="curl", version="7.68.0"),
+        Package(name="requests", version="2.25.1"),
+    ]
+    aptPackages = AptPackages(packages=pkgs)
+    install_via_apt(aptPackages, mock_executor, StdLogger())
+    assert mock_executor.mock_calls == [
+        call.execute(["apt-get", "-y", "update"]),
+        call.execute().print_results(),
+        call.execute(
+            [
+                "apt-get",
+                "install",
+                "-V",
+                "-y",
+                "--no-install-recommends",
+                "curl=7.68.0",
+                "requests=2.25.1",
+            ]
+        ),
+        call.execute().print_results(),
+        call.execute(["apt-get", "-y", "clean"]),
+        call.execute().print_results(),
+        call.execute(["apt-get", "-y", "autoremove"]),
+        call.execute().print_results(),
+        call.execute(["locale-gen", "&&", "update-locale", "LANG=en_US.UTF8"]),
+        call.execute().print_results(),
+        call.execute(["ldconfig"]),
+        call.execute().print_results(),
+    ]
+
+
+# For Sonar Cube Code Coverage - ToDo: Check once if it complains
+def test_prepare_update_command():
+    cmd_strs = prepare_update_command()
+    cmd_str = " ".join(cmd_strs)
+    assert "apt-get" in cmd_str
+    assert "update" in cmd_str
+
+
+def test_prepare_clean_cmd():
+    cmd_strs = prepare_clean_cmd()
+    cmd_str = " ".join(cmd_strs)
+    assert "apt-get" in cmd_str
+    assert "clean" in cmd_str
+
+
+def test_prepare_autoremove_cmd():
+    cmd_strs = prepare_autoremove_cmd()
+    cmd_str = " ".join(cmd_strs)
+    assert "apt-get" in cmd_str
+    assert "remove" in cmd_str
+
+
+def test_prepare_locale_cmd():
+    cmd_strs = prepare_locale_cmd()
+    cmd_str = " ".join(cmd_strs)
+    assert "locale" in cmd_str
+
+
+def test_prepare_ldconfig_cmd():
+    cmd_strs = prepare_ldconfig_cmd()
+    cmd_str = " ".join(cmd_strs)
+    assert "ldconfig" in cmd_str
diff --git a/test/unit/pkg_mgmt/test_cmd_executor.py b/test/unit/pkg_mgmt/test_cmd_executor.py
new file mode 100644
index 0000000..34a5735
--- /dev/null
+++ b/test/unit/pkg_mgmt/test_cmd_executor.py
@@ -0,0 +1,68 @@
+import subprocess
+from unittest.mock import (
+    MagicMock,
+    Mock,
+    call,
+)
+
+import pytest
+
+from exasol.exaslpm.pkg_mgmt.cmd_executor import (
+    CommandExecutor,
+    CommandResult,
+    StdLogger,
+)
+
+
+@pytest.fixture
+def mock_command_result():
+    logger = StdLogger()
+    fn_ret_code = lambda: 10
+    stdout_iter = iter(["stdout line 1", "stdout line 2"])
+    stderr_iter = iter(["stderr line 1", "stderr line 2", "stderr line 3"])
+    return CommandResult(
+        logger, fn_ret_code=fn_ret_code, stdout=stdout_iter, stderr=stderr_iter
+    )
+
+
+def test_command_executor(monkeypatch):
+    mock_popen = MagicMock()
+    monkeypatch.setattr(subprocess, "Popen", mock_popen)
+
+    executor = CommandExecutor(StdLogger())
+    result = executor.execute(["cmd1", "cmd2"])
+    ret_code = result.return_code()
+    assert mock_popen.mock_calls == [
+        call(["cmd1", "cmd2"], stdout=-1, stderr=-1, text=True),
+        call().stdout.__iter__(),
+        call().stderr.__iter__(),
+        call().wait(),
+    ]
+    assert ret_code == mock_popen.return_value.wait.return_value
+
+
+def test_command_results(monkeypatch, mock_command_result):
+    call_counts = {"stdout": 0, "stderr": 0}
+
+    def mock_execute(_, cmd_strs):
+        return mock_command_result
+
+    def stdout_results(result_str: str):
+        call_counts["stdout"] += 1
+        expected = "stdout line " + str(call_counts["stdout"])
+        assert expected == result_str
+
+    def stderr_results(result_str: str):
+        call_counts["stderr"] += 1
+        expected = "stderr line " + str(call_counts["stderr"])
+        assert expected == result_str
+
+    monkeypatch.setattr(CommandExecutor, "execute", mock_execute)
+    executor = CommandExecutor(StdLogger())
+    result = executor.execute(["cmd1", "cmd2"])
+    assert result.return_code() == 10
+    return_code = result.consume_results(stdout_results, stderr_results)
+    assert call_counts["stdout"] == 2
+    assert call_counts["stderr"] == 3
+    assert return_code == 10
+    result.print_results()