diff --git a/bin/spack b/bin/spack
index fef793a6ce5..df517c1f1de 100755
--- a/bin/spack
+++ b/bin/spack
@@ -77,8 +77,10 @@ for cmd in spack.cmd.commands:
 args = parser.parse_args()
 
 # Set up environment based on args.
-spack.verbose = args.verbose
+tty.set_verbose(args.verbose)
+tty.set_debug(args.debug)
 spack.debug = args.debug
+
 spack.spack_working_dir = working_dir
 if args.mock:
     from spack.packages import PackageDB
diff --git a/lib/spack/llnl/util/tty/__init__.py b/lib/spack/llnl/util/tty/__init__.py
index fcbafa82a70..3f413cd46ea 100644
--- a/lib/spack/llnl/util/tty/__init__.py
+++ b/lib/spack/llnl/util/tty/__init__.py
@@ -29,10 +29,20 @@
 
 from llnl.util.tty.color import *
 
-debug   = False
-verbose = False
+_debug   = False
+_verbose = False
 indent  = "  "
 
+def set_debug(flag):
+    global _debug
+    _debug = flag
+
+
+def set_verbose(flag):
+    global _verbose
+    _verbose = flag
+
+
 def msg(message, *args):
     cprint("@*b{==>} %s" % cescape(message))
     for arg in args:
@@ -50,13 +60,13 @@ def info(message, *args, **kwargs):
 
 
 def verbose(message, *args):
-    if verbose:
+    if _verbose:
         info(message, *args, format='c')
 
 
-def debug(*args):
-    if debug:
-        info("Debug: " + message, *args, format='*g')
+def debug(message, *args):
+    if _debug:
+        info(message, *args, format='g')
 
 
 def error(message, *args):
diff --git a/lib/spack/spack/util/executable.py b/lib/spack/spack/util/executable.py
index d65f7ed9222..2b1b24b728a 100644
--- a/lib/spack/spack/util/executable.py
+++ b/lib/spack/spack/util/executable.py
@@ -38,6 +38,7 @@ def __init__(self, name):
         self.exe = name.split(' ')
         self.returncode = None
 
+
     def add_default_arg(self, arg):
         self.exe.append(arg)
 
@@ -61,7 +62,7 @@ def __call__(self, *args, **kwargs):
                      "Consider removing them")
 
         cmd = self.exe + list(args)
-        tty.verbose(" ".join(cmd))
+        tty.debug(" ".join(cmd))
 
         try:
             proc = subprocess.Popen(
@@ -80,6 +81,19 @@ def __call__(self, *args, **kwargs):
         except subprocess.CalledProcessError, e:
             if fail_on_error: raise
 
+
+    def __eq__(self, other):
+        return self.exe == other.exe
+
+
+    def __neq__(self, other):
+        return not (self == other)
+
+
+    def __hash__(self):
+        return hash((type(self),) + tuple(self.exe))
+
+
     def __repr__(self):
         return "<exe: %s>" % self.exe