When Macaulay 2 is built, i.e., is compiled, the directory tree containing the compiled (object) files may be different from the directory tree containing the source code. The source home directory is the directory in that tree named
Macaulay2 and containing subdirectories called
c,
d,
e, and
dumpdata. Knowing that directory allows Macaulay2 to construct a suitable initial value for the
path that allows all the source code files to be found at startup time. If building is not in progress, the value of this variable will be
null.