Most of the directories related to D-Bus append -1 to the name: /etc/dbus-1, /usr/share/dbus-1, etc. (but not /var/lib/dbus, for some reason). What is the meaning/rationale behind -1?
1 Answer
The -1 reflects the API version, and is used in directory names to support parallel installations of a D-Bus 1 implementation and a hypothetical D-Bus 2 implementation (or any other combination).
This is hinted at by the old changelog:
- dbus-1.pc.in, dbus-glib-1.pc.in: rename these from dbus-1.0.pc.in, dbus-glib-1.0.pc.in. As these change with the parallel install API version, not with the D-BUS package version.
(It's not referring to dbus-1 folder names but I think the same reasoning applies there...)
It's an example of D-Bus following its own advice; from the specification:
It is also a good idea to include the major version of the interface in the name, and increment it if incompatible changes are made; this way, a single object can implement several versions of an interface in parallel, if necessary.