Use non-zero exit codes to indicate various situations; See #46

doc/source/api.rst

@@ -27,6 +27,22 @@ and ``/etc/tracer/hooks/``. Such hook will be called when tracer determines, tha
    If you want to run tracer's hooks and print no other output, use ``tracer --hooks-only``
 
 
+Exit codes
+----------
+
+In some use-cases you may want to examine Tracer's results through exit codes (also known as status codes). See their
+meanings:
+
+=======  ================================
+1-99     Error exit codes
+0        No affected applications
+101      Found some affected applications
+102      Found some affected daemons
+103      Session restart needed
+104      Reboot needed
+=======  ================================
+
+
 Data structures
 ---------------
 

tracer/controllers/default.py

@@ -69,6 +69,7 @@ def render(self):
 			view.assign("applications", self.applications)
 			view.assign("args", self.args)
 			view.render()
+		exit(self.status_code())
 
 	def render_helpers(self):
 		helper_controller = HelperController(self.args)
@@ -113,6 +114,28 @@ def render_interactive(self):
 			sys.stdout.write("\n-- " + _("Press <enter> to get list of applications") + " --")
 			input()
 
+	def status_code(self):
+		"""
+		0   - No affected applications
+		101 - Found some affected applications
+		102 - Found some affected daemons
+		103 - Session restart needed
+		104 - Reboot needed
+		"""
+		code = 0
+		if len(self.applications) > 0:
+			code = 101
+
+		if self.applications.count_type(Applications.TYPES['DAEMON']):
+			code = 102
+
+		if self.applications.count_type(Applications.TYPES['SESSION']):
+			code = 103
+
+		if self.applications.count_type(Applications.TYPES['STATIC']):
+			code = 104
+		return code
+
 	def _restartable_applications(self, applications, args):
 		return applications.exclude_types([
 			Applications.TYPES['STATIC'],

tracer/main.py

@@ -43,5 +43,6 @@ def run():
 
 	except (UnsupportedDistribution, PathNotFound, LockedDatabase) as ex:
 		print(ex)
+		exit(1)
 	except (KeyboardInterrupt, EOFError):
 		print("")