Copy the latest chemkin file to chem.inp

Whenever the latest chemXXXX.inp file is written, it is copied (or rather hard-linked)
to chemkin/chem.inp, so that you can always just look at this file and get the latest.

Author: rwest

rmg.py

@@ -343,7 +343,12 @@ def execute(args):
 
         # Save a Chemkin file containing the current model core
         logging.info('Saving latest model core to Chemkin file...')
-        reactionModel.saveChemkinFile(os.path.join(settings.outputDirectory, 'chemkin', 'chem%04i.inp' % len(reactionModel.core.species)))
+        this_chemkin_path = os.path.join(settings.outputDirectory, 'chemkin', 'chem%04i.inp' % len(reactionModel.core.species))
+        latest_chemkin_path = os.path.join(settings.outputDirectory, 'chemkin','chem.inp')
+        reactionModel.saveChemkinFile(this_chemkin_path)
+        if os.path.exists(latest_chemkin_path):
+            os.unlink(latest_chemkin_path)
+        os.link(this_chemkin_path,latest_chemkin_path)
 
         # Save the restart file if desired
         if settings.saveRestart: