Constant UNIX_EPOCH 

pub const UNIX_EPOCH: SystemTime;

The wall clock [now_micros] reads on a host build. On wasm the clock comes from JS instead, so importing this there is an unused_imports warning — the mirror of the dead-const warning the host build would give the other half of the same function. An anchor in time which can be used to create new SystemTime instances or learn about where in time a SystemTime lies.

This constant is defined to be “1970-01-01 00:00:00 UTC” on all systems with respect to the system clock. Using duration_since on an existing SystemTime instance can tell how far away from this point in time a measurement lies, and using UNIX_EPOCH + duration can be used to create a SystemTime instance to represent another fixed point in time.

duration_since(UNIX_EPOCH).unwrap().as_secs() returns the number of non-leap seconds since the start of 1970 UTC. This is a POSIX time_t (as a u64), and is the same time representation as used in many Internet protocols.

Examples

use std::time::{SystemTime, UNIX_EPOCH};

match SystemTime::now().duration_since(UNIX_EPOCH) {
    Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),
    Err(_) => panic!("SystemTime before UNIX EPOCH!"),
}