problem building GD on Ubuntu 'Jaunty'

I'm having trouble building gdlib. As far as I can tell, zlib, png and all the rest are installed in either /lib or /usr/lib. It does not seem to matter whether I use --prefix or one or all of the --with-, the configure script keeps on insisting that it can't find any of the supporti开发者_StackOverflowng libraries.

** Configuration summary for gd 2.0.34:

   Support for PNG library:          no
   Support for JPEG library:         no
   Support for Freetype 2.x library: no
   Support for Fontconfig library:   no
   Support for Xpm library:          no
   Support for pthreads:             yes

[EDIT] Now I've noticed that libpthread was found. Hunting around the disk I find libpthread.so. What I don't find is libpng.so. What I do find is /usr/lib/libpng12.so.0. So what's this zero on the end? Is this why Gd's configure isn't working? What do I do about this?

This is all because Concrete5's installer is telling me it can't find GD.

# cd /usr/lib
# ln -s libpng.so libpng12.so.0
# ldconfig

This creates a softlink to libpng12.so.0 using the filename that compilation expects, then runs ldconfig (must be run as root!) to rebuild the library cache.

If you want to check if your system knows about libraries or not, use the following command:

# ldconfig -p |grep <library_name>

try running ldconfig to refresh the list of libraries