* Installing *source* package 'rgdal' ...
./configure: line 1: gdal-config: command not found

I was unable to find the gdal-config script distributed with
GDAL. If you have not installed the GDAL libraries, you can
download the source from  http://www.remotesensing.org/gdal/
If you have installed the GDAL libraries, then make sure that
gdal-config is in your path. Try typing gdal-config at a
shell prompt and see if it runs. If not, find it and add its
path to your shell path.

ERROR: configuration failed for package 'rgdal'