[MultiDB] sonic-db-cli should support EVAL operation, app script use … (

sonic-net#58)

* [MultiDB] sonic-db-cli should support EVAL operation, app script use it in this way
* unify client.execute_command

src/swsssdk/scripts/sonic-db-cli

@@ -4,9 +4,12 @@ import swsssdk
 
 argc = len(sys.argv)
 if argc == 2 and sys.argv[1] == '-h':
-    print "Example 1: sonic-db-cli CONFIG_DB keys *"
-    print "Example 2: sonic-db-cli APPL_DB HGETALL VLAN_TABLE:Vlan10"
-    print "Example 3: sonic-db-cli APPL_DB HGET VLAN_TABLE:Vlan10 mtu"
+    print("""
+Example 1: sonic-db-cli CONFIG_DB keys *
+Example 2: sonic-db-cli APPL_DB HGETALL VLAN_TABLE:Vlan10
+Example 3: sonic-db-cli APPL_DB HGET VLAN_TABLE:Vlan10 mtu
+Example 4: sonic-db-cli APPL_DB EVAL "return {KEYS[1],KEYS[2],ARGV[1],ARGV[2]}" 2 k1 k2 v1 v2
+""")
 elif argc < 3:
     msg = "'Usage: sonic-db-cli <db_name> <cmd> [arg [arg ...]]'. See 'sonic-db-cli -h' for detail examples."
     print >> sys.stderr, msg
@@ -20,4 +23,5 @@ else:
         print >> sys.stderr, msg
     else:
         client = dbconn.get_redis_client(dbname)
-        print client.execute_command(" ".join(sys.argv[2:]))
+        args = sys.argv[2:]
+        print client.execute_command(*args)