Fix #187 on linux

cps/helper.py

@@ -81,7 +81,7 @@ def make_mobi(book_id, calibrepath):
     file_path = os.path.join(calibrepath, book.path, data.name)
     if os.path.exists(file_path + u".epub"):
         p = subprocess.Popen((kindlegen + " \"" + file_path + u".epub\"").encode(sys.getfilesystemencoding()),
-                             stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+                             stdout=subprocess.PIPE, stderr=subprocess.PIPE,shell=True )
         # Poll process for new output until finished
         while True:
             nextline = p.stdout.readline()