How do I set the system clock in Rust?

Question

For ham radio field day, I have a GPS dongle that I want to use to set my Linux laptop’s system time when I’m in the outback, where there’s no Internet access.

How do you set the system clock time in Rust?

PS: I checked crates.io but nothing stood out to me as a solution.

Answer 1

Since this looks less of a "I want to write a solid library" and more like a "hack it together" kind of thing, a few options, some hacky:

• You could just shell out to coreutils' date:

  std::process::Command::new("date")
      // Produce the date string with some crate: date, chrono, hifitime, ...
      .args(["--set", "2023-12-14 01:23:45.678"])
      .env_clear()
      .env("LC_ALL", "C.UTF-8")
      .output()
  

  Playground
  (See comments about accuracy!)

• You could run date with strace and see that it uses the clock_settime syscall. Usually, you can find a safe and nicely typed wrapped version of that syscall in the nix crate. If you can't find it, check libc.

• There is a rust reimplementation of coreutils (turns up in a search too), you could check what that does.

All of these of course require the appropriate permission, of course, either being root or having a capability set.

---

Side note: I wholeheartedly agree with @n0rd's comment. I don't know how you're reading from your gps dongle, but if it's already gpsd there's no point, and if it's some lower-level method, I assume you'll run into fun problems (Week number rollover comes to mind).