Overloading a built-in command no longer causes infinite recursion, built-in commands are not lost when overloaded, and multiple commands can be overloaded in the same way. Using an alias to overload a command is still dangerous.

shell.py

@@ -20,7 +20,7 @@
 #  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 #  MA 02110-1301, USA.
 #  
-#  Ver. 0.1.0032
+#  Ver. 0.1.0033
 
 
 import types as _types
@@ -193,6 +193,7 @@ conventionally called args or argv"""
         b = self.getBatch(ret[0])
         if b:
             ret = b + ret
+        ret[0] = _re.sub(r'\A\$\((\w+)\)', r'\1', ret[0])
         return ret
     
     # Default functions
@@ -207,14 +208,15 @@ conventionally called args or argv"""
         
     def defineBatch(self, args):
         """Define a batch file."""
-        if len(args) != 1:
-            raise ValueError('def takes only one argument')
+        if len(args) < 1:
+            raise ValueError('def takes at least one argument')
         ret = []
         command = input(self.ps2)
         while command != 'end':
             ret.append(command)
             command = input(self.ps2)
-        self.registerBatch(args[0], ret)
+        for i in args:
+            self.registerBatch(i, ret)
         
     def batch(self, args):
         """Run commands in batch mode
@@ -243,6 +245,8 @@ $>=0 - $>=n is the nth and later arguments"""
                     newLine = newLine.replace(m.group(), ' '.join(args[num:]))
                 else:
                     newLine = newLine.replace(m.group(), args[int(n)])
+            newLine = _re.sub(r'\A({0})'.format(args[0]), r'$(\1)', newLine)
+            #print(newLine)
             self.handleCommand(self.scanLine(newLine))
         
     # Beyond this point are functions that are called within the main loop.