export CC=cc : This command allows you to use gcc's C compiler instead of gnat's C compiler. export PATH_HOLD=$PATH : This command stores your current path before it's modified so that it can be restored after installation. export PATH=/usr/src/gnat/bin:$PATH : This command allows the build to find gnat's Ada compiler to build Ada. --enable-languages=c,c++,objc,f77,ada,java : This command builds all available languages in the gcc package except java. You can modify this command to remove unwanted languages. If you are removing Ada, use the separate installation instructions below. --enable-shared --enable-threads=posix --enable-__cxa_atexit : These commands are required to build the C++ libraries to published standards. --with-slibdir=/lib : This command sets the path to libgcc_s.so. --enable-clocale=gnu : This command is a failsafe for incomplete localedata. touch treeprs.ads [es]info.h nmake.ad[bs] : This command creates necessary files for the Ada build. make gnatlib_and tools : This command completes the Ada build process.