Unix Timestamp in Rust

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

let epoch = SystemTime::now()
    .duration_since(UNIX_EPOCH)
    .expect("Time went backwards");

println!("{}", epoch.as_secs());        // seconds
println!("{}", epoch.as_millis());      // milliseconds
println!("{}", epoch.as_nanos());       // nanoseconds

[dependencies]
chrono = "0.4"

use chrono::{Utc, TimeZone, DateTime};

// Current timestamp
let now: DateTime<Utc> = Utc::now();
println!("{}", now.timestamp());          // seconds
println!("{}", now.timestamp_millis());   // milliseconds
println!("{}", now.to_rfc3339());         // ISO 8601

// Epoch to DateTime
let dt = Utc.timestamp_opt(1700000000, 0).unwrap();
println!("{}", dt);                       // 2023-11-14 22:13:20 UTC
println!("{}", dt.to_rfc3339());          // "2023-11-14T22:13:20+00:00"
println!("{}", dt.format("%Y-%m-%d %H:%M:%S"));

// DateTime to epoch
let epoch: i64 = dt.timestamp();

// Cargo.toml: chrono-tz = "0.8"
use chrono::Utc;
use chrono_tz::Asia::Kolkata;

let utc = Utc.timestamp_opt(1700000000, 0).unwrap();
let ist = utc.with_timezone(&Kolkata);
println!("{}", ist);                     // 2023-11-15 03:43:20 IST

use chrono::{Utc, Duration};

let now = Utc::now();
let future = now + Duration::days(1);
let past   = now - Duration::hours(6);

// Check expiry
let expiry = Utc.timestamp_opt(1700000000, 0).unwrap();
if Utc::now() > expiry {
    println!("expired");
}