--- a/pkgs/.install.py> 2016-10-22 22:34:35.739932506 +0800
+++ b/pkgs/.install.py> 2016-10-22 22:35:04.296779737 +0800
@@ -44,6 +44,7 @@
-
 # these may be changed in main()
 ROOT_PREFIX = sys.prefix
+instdir = ROOT_PREFIX
 PKGS_DIR = join(ROOT_PREFIX, 'pkgs')
 SKIP_SCRIPTS = False
 FORCE = False
@@ -1145,7 +1146,9 @@
     return res
-
-
-def update_prefix(path, new_prefix, placeholder, mode):
+def update_prefix(path, new_prefix, placeholder, mode, instdir=None):
+    if not instdir is None:
+        new_prefix = instdir
     if on_win:
         # force all prefix replacements to forward slashes to simplify need
         # to escape backslashes - replace with unix-style path separators
@@ -1269,7 +1272,7 @@
     return set(fn[:-5] for fn in os.listdir(meta_dir) if fn.endswith('.json'))
-
-
-def link(prefix, dist, linktype=LINK_HARD):
+def link(prefix, dist, linktype=LINK_HARD, instdir=None):
     '''
     Link a package in a specified prefix.  We assume that the packacge has
     been extra_info in either
@@ -1309,7 +1312,7 @@
     for f in sorted(has_prefix_files):
         placeholder, mode = has_prefix_files[f]
         try:
-            update_prefix(join(prefix, f), prefix, placeholder, mode)
+            update_prefix(join(prefix, f), prefix, placeholder, mode, instdir)
         except PaddingError:
             sys.exit("ERROR: placeholder '%s' too short in: %s\n" %
                      (placeholder, dist))
@@ -1384,7 +1387,7 @@
         prefix = prefix_env(env_name)
         for dist in dists:
             assert dist in IDISTS
-            link(prefix, dist, linktype)
+            link(prefix, dist, linktype, instdir)
-
         for dist in duplicates_to_remove(linked(prefix), dists):
             meta_path = join(prefix, 'conda-meta', dist + '.json')
@@ -1419,7 +1422,7 @@
-
-
 def main():
-    global ROOT_PREFIX, PKGS_DIR, FORCE
+    global ROOT_PREFIX, PKGS_DIR, FORCE, instdir
-
     p = OptionParser(description="conda link tool used by installers")
-
@@ -1428,6 +1431,10 @@
                  default=abspath(join(__file__, '..', '..')),
                  help="root prefix (defaults to %default)")
-
+    p.add_option('--instdir',
+                 action="store",
+                 help="install dir (defaults to root prefix)")
+
     p.add_option('--post',
                  action="store",
                  help="perform post extract (on a single package), "
@@ -1439,6 +1446,10 @@ p.error('no arguments expected')
-
     ROOT_PREFIX = opts.root_prefix
+    if not opts.instdir:
+        instdir = ROOT_PREFIX
+    else:
+        instdir = opts.instdir
     PKGS_DIR = join(ROOT_PREFIX, 'pkgs')
-
     if opts.post: