In Unix Everything Is a File

#1

Post by mutor » Sat, Jul 21, 2018, 12:07 PM UTC

In Unix Everything Is a File
ph7spot.com

Re: In Unix Everything Is a File

#2

Post by lvh » Sat, Jul 21, 2018, 1:31 PM UTC

And it looks like the server may have run out of files (well, descriptors) :-)

google cache link: https://webcache.googleusercontent.com/search?q=cache:L6aopS...

Re: In Unix Everything Is a File

#3

Post by lucb1e » Sat, Jul 21, 2018, 1:34 PM UTC

Wordpress strikes again.

Page is from 2014. Archive link: https://web.archive.org/web/20091119184152/https://ph7spot.c...

Edit: archive of 6 years ago with some styling: http://archive.is/B9He (The page actually loaded for me on the second try, and the design looks a lot more modern now.)

Re: In Unix Everything Is a File

#4

Post by rzzzt » Sat, Jul 21, 2018, 1:39 PM UTC

Which was the last Unix release/flavor where you could still read(2) a directory? All manpages that I've found say that you get EISDIR if you try it.

Re: In Unix Everything Is a File

#5

Post by Pete_D » Sat, Jul 21, 2018, 1:58 PM UTC

rzzzt wrote: post #4

Which was the last Unix release/flavor where you could still read(2) a directory? All manpages that I've found say that you get EISDIR if you try it.

I certainly remember being surprised when I accidentally cat'd a directory on AIX and it worked. I can't remember exactly what you get back; I think it's a NUL-separated list of the files in it.

Re: In Unix Everything Is a File

#6

Post by ArtWomb » Sat, Jul 21, 2018, 2:00 PM UTC

Is the sendfile system call still the fastest way to transfer data locally on Linux systems?

For communicating between processes running locally on system. Or, for example, a server running locally on an android device. Unix domain sockets typically beat TCP connections for most large file transfers. But is there anything faster?

And what about transfers over the public net from machine to machine? I usually just use netcat, ssh, or scp.

Re: In Unix Everything Is a File

#7

Post by zokier » Sat, Jul 21, 2018, 2:19 PM UTC

I think the author might have confused Plan9 and UNIX.

Re: In Unix Everything Is a File

#8

Post by DonHopkins » Sat, Jul 21, 2018, 2:36 PM UTC

zokier wrote: post #7

I think the author might have confused Plan9 and UNIX.

He also confused "The Art of UNIX Programming" with a "fantastic book".

Re: In Unix Everything Is a File

#9

Post by Pete_D » Sat, Jul 21, 2018, 2:39 PM UTC

"Everything is a file" is a nice idea not taken far enough. The execution is full of frustrating omissions and holes at the edges, e.g.:

- unless you are using Plan 9 or gpm, reading mouse events is almost certainly going to be a lot more involved than opening /dev/mouse

- you can't portably use select() to wait on pthread conditions

- lots of useful things (like POSIX shared memory objects) are file descriptors, but aren't filesystem namespaced

Sometimes I wonder what the world would look like if Plan 9 had won.

Re: In Unix Everything Is a File

#10

Post by pjmlp » Sat, Jul 21, 2018, 2:40 PM UTC

Any UNIX old timer knows that actually:

In UNIX everything is a file, except when it is not.