--- a/agl.py	Mon Sep 11 20:57:54 2017 +0930
+++ b/agl.py	Mon Sep 11 22:09:37 2017 +0930
@@ -28,6 +28,7 @@
     parser.add_argument('-u', '--update', help = 'Update data', action="store_true")
     parser.add_argument('-g', '--graph', help = 'Produce graph', action="store_true")
     parser.add_argument('-f', '--filename', help = 'Filename to save graph as (uses strftime on start)', type = str)
+    parser.add_argument('-d', '--days', help = 'Days ago to graph', type = int)
     parser.add_argument('-s', '--start', help = 'Start date for graph (YYYY-MM-DD)', type = valid_date)
     parser.add_argument('-e', '--end', help = 'End date for graph (YYYY-MM-DD)', type = valid_date)
 
@@ -40,9 +41,6 @@
     password = conf.get('DEFAULT', 'password')
     dbfn = conf.get('DEFAULT', 'db')
 
-    if (args.start is None) ^ (args.end is None):
-        parser.error('Must specify start and end or neither')
-
     if not args.update and not args.graph:
         parser.error('Nothing to do')
 
@@ -51,10 +49,14 @@
         start = datetime.date.today()
         start = datetime.datetime(start.year, start.month, start.day)
 
+    if args.days is not None:
+        start -= datetime.timedelta(days = args.days)
+
     end = args.end
     if end is None:
         end = start + datetime.timedelta(days = 1)
         end = datetime.datetime(end.year, end.month, end.day)
+
     dbh = sqlite3.connect(dbfn, detect_types = sqlite3.PARSE_DECLTYPES)
     cur = dbh.cursor()
     if args.update: