fix behaviour on machines with 1 single instrument

- complain when instrument name is MAIN in servicemanager.cfg
- set self.main_ins also on single instrument machines

base.py

@@ -1,4 +1,3 @@
-#  -*- coding: utf-8 -*-
 # *****************************************************************************
 #
 # This program is free software; you can redistribute it and/or modify it under
@@ -140,13 +139,17 @@ class ServiceManager:
             value = value.replace('<INS>', ins)
             return ':'.join(expanduser(p % dict(ins=ins)) for p in value.split(':'))
 
-        this_ins = os.environ.get('Instrument') or basename(expanduser('~'))
-        for ins in parser.sections():
+        hostname = socket.gethostname().split('.')[0]
+        self.is_remote = hostname != section.get('host', hostname)
+        all_ins = [k for k in parser.sections() if parser.has_option(k, self.group)]
+        if len(all_ins) == 1:
+            self.main_ins = self.single_ins = all_ins[0]
+        else:
+            self.main_ins = os.environ.get('Instrument') or hostname
+        for ins in all_ins:
+            if ins == 'MAIN':
+                raise ValueError('error in ~/servicemanager.cfg: replace [MAIN] by [<instrument name>]')
             section = dict(parser[ins])
-            if ins == this_ins:
-                self.main_ins = this_ins
-            hostname = socket.gethostname().split('.')[0]
-            self.is_remote = hostname != section.get('host', hostname)
             command = section.get('%s_command' % self.group)
             self.revcmd[command] = self.group
             nr = section.get(self.group)
@@ -161,8 +164,6 @@ class ServiceManager:
                     cmd = env.get('PY', 'python3') + cmd[2:]
                 self.commands[ins] = cmd
         self.info = result
-        if len(self.info) == 1:
-            self.single_ins = list(self.info)[0]
         return result
 
     #def get_cmdpats(self, groups):
@@ -219,7 +220,7 @@ class ServiceManager:
                     match = cmdpat.match(cmd)
                     if match:
                         gdict = match.groupdict()
-                        ins = gdict.get('ins', self.main_ins) or self.single_ins
+                        ins = gdict.get('ins', self.main_ins)
                         serv = gdict.get('serv', '')
                         if cfginfo is not None and 'cfg' in gdict:
                             cfginfo[ins, serv] = gdict['cfg']