+you can set and what kinds of files go in them. In general, the
+default for these options is expressed in terms of ‘${prefix}’, so that
+specifying just ‘--prefix’ will affect all of the other directory
+specifications that were not explicitly provided.
+
+ The most portable way to affect installation locations is to pass the
+correct locations to ‘configure’; however, many packages provide one or
+both of the following shortcuts of passing variable assignments to the
+‘make install’ command line to change installation locations without
+having to reconfigure or recompile.
+
+ The first method involves providing an override variable for each
+affected directory. For example, `make install
+prefix=/alternate/directory' will choose an alternate location for all
+directory configuration variables that were expressed in terms of
+‘${prefix}’. Any directories that were specified during ‘configure’,
+but not in terms of ‘${prefix}’, must each be overridden at install
+time for the entire installation to be relocated. The approach of
+makefile variable overrides for each directory variable is required by
+the GNU Coding Standards, and ideally causes no recompilation.
+However, some platforms have known limitations with the semantics of
+shared libraries that end up requiring recompilation when using this
+method, particularly noticeable in packages that use GNU Libtool.
+
+ The second method involves providing the ‘DESTDIR’ variable. For
+example, ‘make install DESTDIR=/alternate/directory’ will prepend
+‘/alternate/directory’ before all installation names. The approach of
+‘DESTDIR’ overrides is not required by the GNU Coding Standards, and
+does not work on platforms that have drive letters. On the other hand,
+it does better at avoiding recompilation issues, and works well even
+when some directory options were not specified in terms of ‘${prefix}’
+at ‘configure’ time.
+
+Optional Features
+=================