Write log header only when needed

sohstationviewer/model/reftek_data/reftek.py

@@ -138,13 +138,21 @@ class RT130(GeneralData):
         for key in self.log_data:
             if key == 'TEXT':
                 continue
-            current_time = datetime.datetime.now().ctime()
-            soh_header = (f'SOHStationViewer: v{SOFTWARE_VERSION} '
-                          f'Run time (UTC): {current_time}\n')
+            soh_header = ''
             soh_footer = ''
+            soh_messages = self.log_data[key]['SOH']
+            possible_programs = ['logpeek', 'SOHStationViewer', 'rt2ms']
+            message_has_header = any(soh_messages[0].startswith(program)
+                                     for program
+                                     in possible_programs)
+            if not message_has_header:
+                current_time = datetime.datetime.now().ctime()
+                soh_header = (f'SOHStationViewer: v{SOFTWARE_VERSION} '
+                              f'Run time (UTC): {current_time}\n')
             if self.include_masspos_in_soh_messages:
                 soh_footer += '\n\nMass-positions:\n'
                 mass_pos_lines = []
+                soh_messages = self.log_data[key]['SOH']
                 for chan in self.mass_pos_data[key]:
                     chan_data = self.mass_pos_data[key][chan]
                     # We combined all data into one trace above
@@ -158,7 +166,6 @@ class RT130(GeneralData):
                     ]
                     mass_pos_lines.extend(formatted_lines)
                 soh_footer += '\n'.join(mass_pos_lines)
-            soh_messages = self.log_data[key]['SOH']
             soh_messages[0] = soh_header + soh_messages[0] + soh_footer
 
     def read_log_files(self):