diff --git a/src/beastcleaner.nim b/src/beastcleaner.nim
index 05ba563..1dcde4c 100644
--- a/src/beastcleaner.nim
+++ b/src/beastcleaner.nim
@@ -22,3 +22,85 @@
 # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 # OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+## The main module of the program.
+
+import std/[os, parseopt]
+import contracts
+
+proc showCommandLineHelp() {.sideEffect, raises: [], tags: [WriteIOEffect],
+    contractual.} =
+  ## Show the program arguments help
+  ##
+  ## Return QuitSuccess when the program's arguments help was shown, otherwise
+  ## QuitFailure.
+  body:
+    try:
+      stdout.writeLine(x = """Available options are:
+      -h, --help    - Show this help and quit
+      -v, --version - Show the program version info
+
+Available arguments are:
+      clean         - Clean interactively the system""")
+      stdout.flushFile
+    except IOError:
+      when isMainModule:
+        quit QuitFailure
+    when isMainModule:
+      quit QuitSuccess
+
+proc showProgramVersion() {.sideEffect, raises: [], tags: [WriteIOEffect],
+    contractual.} =
+  ## Show the program version
+  ##
+  ## Returns QuitSuccess when the program's arguments help was shown, otherwise
+  ## QuitFailure.
+  body:
+    try:
+      stdout.writeLine(x = """
+      Beastcleaner version: 0.1.0
+
+      Copyright: 2024 Bartek Jasicki <thindil@laeran.pl.eu.org>
+      License: 3-Clause BSD""")
+      stdout.flushFile
+    except IOError:
+      when isMainModule:
+        quit QuitFailure
+    when isMainModule:
+      quit QuitSuccess
+
+
+proc main() {.raises: [], tags: [ReadIOEffect, WriteIOEffect], contractual.} =
+  ## The main procedure of the program
+  var options: OptParser = initOptParser(shortNoVal = {'h', 'v'}, longNoVal = @[
+        "help", "version"])
+  type Setting = string
+  const
+    awkScript: Setting = "/tmp/beastcleaner.awk"
+    pkgList: Setting = "/tmp/list1.txt"
+    filesList: Setting = "/tmp/list2.txt"
+    filesDiff: Setting = "/tmp/beastdiff.txt"
+
+  # Check the program's arguments and options
+  while true:
+    options.next
+    case options.kind
+    of cmdEnd:
+      break
+    of cmdShortOption, cmdLongOption:
+      case options.key
+      of "h", "help":
+        showCommandLineHelp()
+      of "v", "version":
+        showProgramVersion()
+      else:
+        quit "Unknown option '" & options.key & "'. To see all available options, run the program with --help."
+    of cmdArgument:
+      case options.key:
+      of "clean":
+        if not isAdmin():
+          quit "To clean the system, please run the program as root, via su, sudo, dosu, etc."
+      else:
+        quit "Unknown argument '" & options.key & "'. To see all available arguments, run the program with --help."
+
+main()