n directory.
  </P
><P
><I
CLASS="EMPHASIS"
>FC_DEBUG</I
>
is used to output the detailed debugging messages. see <A
HREF="#DEBUG"
>Debugging Applications</A
> section for more details.
  </P
><P
><I
CLASS="EMPHASIS"
>FONTCONFIG_USE_MMAP</I
>
is used to control the use of mmap(2) for the cache files if available. this take a boolean value. fontconfig will checks if the cache files are stored on the filesystem that is safe to use mmap(2). explicitly setting this environment variable will causes skipping this