util: create ~/.manpath when missing for -m true

Previously update_mandb_path() silently returned if ~/.manpath did
not exist, so 'cppman -m true' had no effect on a fresh system and
users had to 'touch ~/.manpath' first (#136, #98). Catch
FileNotFoundError specifically and continue with an empty file so
the MANDATORY_MANPATH / MANDB_MAP entries are written.

Also clarify the help text for -r/--rebuild-index, which has always
rebuilt both sources rather than only the configured one (#154).

Author: aitjcize

bin/cppman

@@ -88,8 +88,8 @@ def main():
                     "The default value is 'vim'."),
         make_option('-r', '--rebuild-index', action='store_true',
                     dest='rebuild_index', default=False,
-                    help="rebuild index database for the selected source, "
-                    "either 'cppreference.com' or 'cplusplus.com'."),
+                    help="rebuild index database from both sources "
+                    "('cppreference.com' and 'cplusplus.com')."),
         make_option('-v', '--version', action='store_true', dest='version',
                     default=False, help='Show version information.'),
         make_option('--force-columns', action='store', dest='force_columns',

cppman/util.py

@@ -41,12 +41,12 @@ def update_mandb_path():
 
     lines = []
 
-    """ read all lines """
+    """ read all lines if the file already exists """
     try:
         with open(manpath_file, 'r') as f:
             lines = f.readlines()
-    except IOError:
-        return
+    except FileNotFoundError:
+        pass
 
     """ remove MANDATORY_MANPATH and MANDB_MAP entry """
     lines = [line for line in lines if man_dir not in line]