If you use project files, library installation is part of the library build process (see the `Installing a Library with Project Files' section of the `GNAT Project Manager' chapter of the `GPRbuild User’s Guide').
When project files are not an option, it is also possible, but not recommended,
to install the library so that the sources needed to use the library are on the
Ada source path and the ALI files & libraries be on the Ada Object path (see
Search Paths and the Run-Time Library (RTL). Alternatively, the system
administrator can place general-purpose libraries in the default compiler
paths, by specifying the libraries’ location in the configuration files
ada_source_path and ada_object_path. These configuration files
must be located in the GNAT installation tree at the same place as the gcc spec
file. The location of the gcc spec file can be determined as follows:
$ gcc -v
The configuration files mentioned above have a simple format: each line must contain one unique directory name. Those names are added to the corresponding path in their order of appearance in the file. The names can be either absolute or relative; in the latter case, they are relative to where theses files are located.
The files ada_source_path and ada_object_path might not be
present in a
GNAT installation, in which case, GNAT will look for its run-time library in
the directories adainclude (for the sources) and adalib (for the
objects and ALI files). When the files exist, the compiler does not
look in adainclude and adalib, and thus the
ada_source_path file
must contain the location for the GNAT run-time sources (which can simply
be adainclude). In the same way, the ada_object_path file must
contain the location for the GNAT run-time objects (which can simply
be adalib).
You can also specify a new default path to the run-time library at compilation
time with the switch --RTS=rts-path. You can thus choose / change
the run-time library you want your program to be compiled with. This switch is
recognized by gcc, gnatmake, gnatbind,
gnatls, gnatfind and gnatxref.
It is possible to install a library before or after the standard GNAT library, by reordering the lines in the configuration files. In general, a library must be installed before the GNAT library if it redefines any part of it.