A linkback can have several potential targets. The
`CLASS' target causes the linkback to point back to the
original filename appended with an extension that is the name of the
node class as determined by the NODECLASS directives.
Similarly, the `NODE' target causes the final target to point
back to the original filename appended with
an extension that is the hostname of the node.
A linkback target can also be any arbitrary pathname. This
target path will be interpolated to replace any instance of
`$CLASS' and
`$NODE' with the class name and hostname of the node, respectively.
Note: Some files cannot have linkbacks created for them for various reasons. The most notable of these are /etc/inittab, /boot/grub/menu.lst, /etc/mtab, and /etc/sysimage.conf.