I have been looking into UUCP (Unix-to-Unix Copy, a very old network protocol) as a way of communicating with some Linux boxes that don't always have an internet connection. While doing so on my Macbook (with El Capitan), I found entries in my /usr/share/uucp/sys file for uucpsys1.apple.com and uucpsys2.apple.com. (You can also see these by running uuchk | less.)

What is Apple doing with UUCP? I found this post on the Apple forums by someone who noticed a UUCP user, but no one came forward with an explanation, so I'm hoping someone here will know.

I'm especially curious because /usr/share/* falls under System Integrity Protection in El Capitan, which means I'll need to set up a separate UUCP implementation if I want to use it for my purposes — but it also suggests that, if Apple's shipping OS X with a UUCP that only they can use, they must be using it for something.

ETA: I've also found a launchd daemon at /System/Library/LaunchDaemons/com.apple.uucp.plist. It has <key>Disabled</key><true/> in the plist, so it won't be run by default, but other daemons could enable it programmatically without altering the plist. I'm also intrigued to see that it's in /System/Library/LaunchDaemons/ (and thus subject to SIP) rather than /Library/LaunchDaemons/ — it adds to my hunch that it's something Apple is using (or maybe was using, as patrix comments), rather than just a miscellaneous *nix tool they happened to include.

  • 3
    Apple is probably doing nothing with UUCP so they didn't even realize that SIP prevents anybody from using it.
    – nohillside
    Feb 4, 2016 at 5:36
  • 3
    Aside: if anyone else is trying to use UUCP on OS X, I figured out that you don't actually need to install an entirely separate implementation: all of the commands let you specify a different configuration file with --config /usr/local/conf/uucp/config, so you just need to create your own define log, spool, etc with that. info uucp was a big help. Feb 4, 2016 at 8:05
  • Neither uucpsys1.apple.com nor uucpsys2.apple.com get resolved in DNS, so whatever it was, it's long gone (or only used internally by Apple).
    – nohillside
    Feb 4, 2016 at 19:50

1 Answer 1


Those entries are examples that can be used as templates in user defined configurations.

See the same examples at:


You can see those examples in the same way as the phone prefix +555 in the movies. It there to show somebody using a phone, but the fake number/name cant be called. Placing an example with a ficticious hostname allows to have a template.

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