pip list command patch

list.patch

diff --git a/pip/commands/list.py b/pip/commands/list.py
index 3a0330a..3e4fcc7 100644
--- a/pip/commands/list.py
+++ b/pip/commands/list.py
@@ -45,6 +45,12 @@ class ListCommand(Command):
             help=('If in a virtualenv that has global access, do not list '
                   'globally-installed packages.'),
         )
+        cmd_opts.add_option(
+            '-L', '--location',
+            action='store_true',
+            default=False,
+            help=('Display package locations.'),
+        )

         cmd_opts.add_option(
             '--pre',
@@ -81,7 +87,7 @@ class ListCommand(Command):
         elif options.editable:
             self.run_editables(options)
         else:
-            self.run_listing(options)
+            self.run_listing(options, args)

     def run_outdated(self, options):
         for dist, remote_version_raw, remote_version_parsed in \
@@ -145,26 +151,30 @@ class ListCommand(Command):
                 remote_version_parsed = remote_version[0]
             yield dist, remote_version_raw, remote_version_parsed

-    def run_listing(self, options):
+    def run_listing(self, options, args):
         installed_packages = get_installed_distributions(
             local_only=options.local,
         )
-        self.output_package_listing(installed_packages)
+        if args:
+            installed_packages = [p for p in installed_packages if p.project_name in args]
+        self.output_package_listing(installed_packages, options)

     def run_editables(self, options):
         installed_packages = get_installed_distributions(
             local_only=options.local,
             editables_only=True,
         )
-        self.output_package_listing(installed_packages)
+        self.output_package_listing(installed_packages, options)

-    def output_package_listing(self, installed_packages):
+    def output_package_listing(self, installed_packages, options):
         installed_packages = sorted(
             installed_packages,
             key=lambda dist: dist.project_name.lower(),
         )
         for dist in installed_packages:
-            if dist_is_editable(dist):
+            if options.location:
+                line = dist.location
+            elif dist_is_editable(dist):
                 line = '%s (%s, %s)' % (
                     dist.project_name,
                     dist.version,
@@ -180,4 +190,4 @@ class ListCommand(Command):
                 self.find_packages_latests_versions(options):
             if dist.parsed_version == remote_version_parsed:
                 uptodate.append(dist)
-        self.output_package_listing(uptodate)
+        self.output_package_listing(uptodate, options)