>
> The placeholder for a Unix domain socket in Solaris is a mode 0 pipe.
> (Though in 2.6 this changes and sockets are again first class citizens)
> As stated in the original unix domain socket documentation "the filesystem
> entry is an artifact of the implementation" or words to that effect.
You'll note that's been changed in 4.4BSD:
Normal
filesystem access-control mechanisms are also applied when referencing
pathnames; e.g., the destination of a connect(2) or sendto(2) must be
writable.
I believe there are other systems which do this as well, and arguably
it's the desired behaviour. However, portable programs can't rely on
it.