Using linkbacks

Linkbacks are the primary technique for defining variant configurations between nodes. A linkback causes a file or directory to become a link into the oneSIS RAM disk, which can then point back to a target in the master image based on a node's class, hostname, or property.

A linkback can have several potential targets. The literal `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 literal `NODE' target causes the final target to point back to the original filename appended with an extension that is the hostname of the node. Since a node can potentially have many properties, the literal `PROPERTY' target causes the linkback to point to the first existing alphanumeric file or directory having an extension that matches one of the node's defined properties.

When not using CLASS, NODE, or PROPERTY, a linkback target can be given as any arbitrary pathname. This 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, and /etc/sysimage.conf.