M

MAKEFLAGS
A set of default options for make.
MALLOC_*
These variables control how the memory allocator behaves; some are supported by the “normal” allocator defined in libc, while some are supported by the librcheck version. For more information, see the entry for mallopt() in the C Library Reference.
MKIFS_PATH
A colon-separated list of directories that mkifs should use to search for host files to be included in an OS image.
MORE
Default options for more.