envvar_get              Get the value of an environment variable
envvar_get_file         Environment variables for files and directories
envvar_get_integer      Get the value of an environment variable as a
                        particular type
envvar_get_list         Environment variables containing lists
envvar_get_url          Environment variables for internet and
                        network-related values
envvar_get_uuid         Environment variables for UUIDs
envvar_is_set           Check whether an environment variable is set
envvar_list             Get a list of environment variables
envvar_set              Set, unset, and check environment variables
