Comment by ddevault | Hacker News Reader

Comment by ddevault | Hacker News Reader

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It's very un-Unix like. In Unix, everything is a file, right? But sockets are entirely managed via syscalls. There are also some very nasty skeletons lying in wait in more obscure parts of the API, such as cmsg.

Consider an alternative design (Plan 9 is something like this, it's been a while so I'm short on details):

1. Open /net/dns and write the desired hostname, then read back the resolved IP address

2. Open /net/tcp/clone and write the address and port, then read back a connection number

3. Open /net/tcp/$conn_id and the file is now a full duplex TCP stream

Compare this to BSD sockets: use getaddrinfo for the DNS lookup (gross!), create a socket with a syscall, then connect the socket with another syscall using sockaddr (gross!). Much worse and much less Unixy.

In unix, everything is a file descriptor [1]. The existence of an actual file entry on the filesystem namespace is not really needed.

[1] that's the ideal of course, reality is different.

Not really. Modern Unixes have evolved towards everything is a file descriptor, but the original design very much called for everything to be a file. Bell Labs started Plan 9 in part as a response to this very issue.

There was no original design for Unix. It never was 1 thing, but a bunch of loose ideas wired (and rewired) together pragmatically over time by different people, usually scratching an itch. I highly recommend Khernigan’s UNIX: A History and a Memoir to get a glimpse of the dynamic.

All the “it’s all a file” idea was added as an ideal along the way because the interface was so dang convenient. But I’ve never read it in any documentation.

Even pipes were added as a “that’s a cool idea.” There was a conversation, a late night coding session and pipes came into existence.

Plan 9 was a response to the evolved (vs designed) Unix. Took “the best” from it and made those design principles. It was an “if we could do it all over again, knowing what we know now” project.

What’s interesting to me is that evolved systems seem to dominate design-first systems in adoption. Maybe it’s that they’re pragmatic. I don’t know. Or maybe my observation is just wrong.

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