The RAMFILE directive creates an empty
file in the RAM disk, and the RAMDIR directive creates an empty directory.
The LINKFILE directive also creates an empty file in the
RAM disk, and the LINKDIR directive creates an empty
directory. In addition the LINK* directives direct the
mk-sysimage script to
alter the corresponding files in the root filesystem to become
symlinks to /ram.
Both sets of directives have their role. The mk-sysimage
script creates the necessary links in the master image.
rc.preinit creates the corresponding files and directories in
the /ram at boot-time or after update-node boots a
node.
File permissions and ownership are mirrored from the root
image, but can be set explicitly for RAM* directives.