Clear out old commands if none specified. Also fix output issue when

launch fails.

wlutil/config.py

@@ -203,6 +203,10 @@ def applyBase(self, baseCfg):
         if 'launch' not in self.cfg:
             self.cfg['launch'] = True
 
+        if 'runSpec' not in self.cfg:
+            self.cfg['run'] = os.path.join(wlutil_dir, 'null_run.sh')
+            self.cfg['runSpec'] = RunSpec(self.cfg)
+
     # The following methods are needed by MutableMapping
     def __getitem__(self, key):
         return self.cfg[key]

wlutil/launch.py

@@ -86,6 +86,7 @@ def launchWorkload(cfgName, cfgs, job='all', spike=False):
             try:
                 run(config['post_run_hook'] + " " + baseResDir, cwd=config['workdir'], shell=True)
             except sp.CalledProcessError as e:
+                log.info("\nRun output available in: " + os.path.dirname(runResDir))
                 raise RuntimeError("Post run hook failed:\n" + e.output)
 
         log.info("\nRun output available in: " + os.path.dirname(runResDir))

wlutil/null_run.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+# This script does nothing, it's used to disable previously specified run scripts or commands
+exit 0