Env Constants

Environment-related constants

Environment Variables

use std::env;

fn main() {
    // Get single variable
    match env::var("HOME") {
        Ok(home) => println!("HOME: {}", home),
        Err(e) => println!("HOME not set: {}", e),
    }

    // var_os returns OsString (doesn't require valid UTF-8)
    if let Some(path) = env::var_os("PATH") {
        println!("PATH (OsString): {:?}", path);
    }

    // Check if exists
    let has_debug = env::var("DEBUG").is_ok();
    println!("\nDEBUG set: {}", has_debug);

    // With default
    let log_level = env::var("LOG_LEVEL").unwrap_or_else(|_| "info".to_string());
    println!("LOG_LEVEL: {}", log_level);

    // Common env vars
    println!("\n=== Common Variables ===");
    for var in ["USER", "SHELL", "LANG", "TERM"] {
        match env::var(var) {
            Ok(val) => println!("{}: {}", var, val),
            Err(_) => println!("{}: (not set)", var),
        }
    }
}