Read environment variables

还没翻译译自英文（bun.com）本页 5 段都还没译

Access the current environment variables with process.env.

process.env.API_TOKEN; // => "secret"

Bun also exposes these variables as Bun.env, an alias of process.env.

Bun.env.API_TOKEN; // => "secret"

To print all currently-set environment variables, run bun --print process.env.

bun --print process.env

ProcessEnv {
  BAZ: "stuff",
  FOOBAR: "aaaaaa",
  <lots more lines>
}