diff --git a/restic_exporter/restic_exporter.py b/restic_exporter/restic_exporter.py
index d42a180..04013bf 100644
--- a/restic_exporter/restic_exporter.py
+++ b/restic_exporter/restic_exporter.py
@@ -51,7 +51,7 @@ class ResticExporter:
         else:
             self._read_summary_from_systemd()
 
-        self._show_metrics()
+        self._write_metrics()
 
     def _read_summary_from_systemd(self,):
         self.summaries = ()
@@ -67,7 +67,7 @@ class ResticExporter:
                     '').replace('.service', '')
                 self.summaries.append(summary)
 
-    def _show_metrics(self):
+    def _write_metrics(self):
         for summary in self.summaries:
             labels = self._convert_labels(self.labels)
             counters = [
@@ -84,14 +84,19 @@ class ResticExporter:
                 'total_bytes_processed',
                 'total_duration'
             ]
-            print(
-                f"# HELP {summary['metric_name']}_{summary['job_name']} {self.metric_description}."
+            if self.config['output_file'] != "-":
+                outfile = open(self.config['output_file'], 'w', encoding='utf-8')
+            else:
+                outfile = sys.stdout
+            outfile.write(
+                f"# HELP {summary['metric_name']}_{summary['job_name']} \
+{self.metric_description}.\n"
             )
-            print(f"# TYPE {summary['metric_name']}_{summary['job_name']} counter")
+            outfile.write(f"# TYPE {summary['metric_name']}_{summary['job_name']} counter\n")
             for counter in counters:
                 if counter in summary:
-                    print(
-                        f"{summary['metric_name']}_{counter}{labels} {float(summary[counter])}"
+                    outfile.write(
+                        f"{summary['metric_name']}_{counter}{labels} {float(summary[counter])}\n"
                     )
 
     def _read_summary_from_json(self, json_file):
@@ -99,7 +104,11 @@ class ResticExporter:
             with open(json_file, 'r', encoding='utf-8') as file_pointer:
                 content = file_pointer.readlines()
         except Exception as error:
-            self._log.error(f"# Error reading file '{json_file}'. Check permissions. {error}")
+            self._log.error(
+                "# Error reading file '%s'. Check permissions. %s",
+                json_file,
+                error
+            )
 
         summary = {
             "timestamp": time.time(),
@@ -116,20 +125,31 @@ class ResticExporter:
                             self.labels["snapshot_id"] = line_data['snapshot_id']
             except json.decoder.JSONDecodeError as error:
                 fixed_line = line.replace('\n', '')
-                self._log.error(f"# Error decoding line '{fixed_line}'. {error}")
+                self._log.error(
+                    "# Error decoding line '%s'. %s",
+                    fixed_line,
+                    error
+                )
         file_stats = os.stat(json_file)
         summary['timestamp'] = round(file_stats.st_mtime * 1000)
-        self._log.debug(f"# Summary: {json.dumps(summary, indent=2)}")
-        self._log.debug(f"# Labels: {self.labels}")
+        self._log.debug("# Summary: {json.dumps(summary, indent=2)}")
+        self._log.debug(
+            "# Labels: %s",
+            self.labels
+        )
         self.summaries = [ summary ]
 
     def _read_extra_labels(self, extra_labels):
         labels_ls = {}
         for pair in extra_labels.split(','):
             if '=' in pair:
-                k, v=pair.split('=', 1)
-                labels_ls[k] = v
-                self._log.debug(f"# Added extra label '{k}'='{v}'")
+                key, value=pair.split('=', 1)
+                labels_ls[key] = value
+                self._log.debug(
+                    "# Added extra label '%s'='%s'",
+                    key,
+                    value
+                )
         return labels_ls
 
     def _convert_labels(self, labels):
@@ -138,9 +158,11 @@ class ResticExporter:
             labels_ls.append(f"{key}=\"{labels[key]}\"")
         text_labels = ','.join(labels_ls)
         labels_string = "{" + text_labels + "}"
-        self._log.debug(f"# Labels: {labels_string}")
+        self._log.debug(
+            "# Labels: %s",
+            labels_string
+        )
         return labels_string
-                
 
     def _init_log(self):
         ''' Initialize log object '''
@@ -180,7 +202,7 @@ class ResticExporter:
         case_sensitive=False,
     ), help='Set the debug level for the standard output.')
 @click.option('--log-file', '-l', help="File to store all debug messages.")
-@click.option("--json-file", "-j", required=True, help='JSON file containing the output of restic')
+@click.option("--json-file", "-j", help='JSON file containing the output of restic')
 @click.option(
     '--job-name', '-n',
     required=True,
@@ -207,6 +229,13 @@ class ResticExporter:
     default=False,
     help='Get JSON data from Systemd units',
 )
+@click.option(
+    '--output-file',
+    '-o',
+    default='-',
+    help='File to write the metrics so node-exporter can read it. Use "-" \
+to write to standard output (default).'
+)
 @click_config_file.configuration_option()
 def __main__(**kwargs):
     return ResticExporter(**kwargs)