Environment variables

It is possible to read, set and unset environment variables. The standard functions env.getenv, env.setenv and env.unsetenv all assume str input and output, which is a convenience based on the assumption that all data is encoded using UTF-8. POSIX systems really use binary encoding for both environment names and variables. To access the environment as bytes and handle decoding explicitly, use env.getenvb, env.setenvb and env.unsetenvb.

Source:

actor main(env):
    env_user = env.getenv("USER")
    if env_user is not None:
        print("User:", env_user)
    env.setenv("FOO", "bar")
    env.unsetenv("LANG")
    foo_env = env.getenv("FOO")
    if foo_env is not None:
        print("FOO:", foo_env)
    env.exit(0)

Output:

User: myuser
FOO: bar