I think "everything is a file" also means: everything is addressable by a file path. Per-process namespaces are part of what makes this possible.
In a way it's similar to HTTP REST, which is also organized by file paths, except instead of the HTTP verbs GET, POST etc. you get open, read, write as your verbs.
In a way it's similar to HTTP REST, which is also organized by file paths, except instead of the HTTP verbs GET, POST etc. you get open, read, write as your verbs.
A side channel is then just a directory entry.