| envvar_get | Get the value of an environment variable | 
| envvar_get_csv | Environment variables containing lists | 
| envvar_get_date | Get the value of an environment variable as a particular type | 
| envvar_get_datetime | Get the value of an environment variable as a particular type | 
| envvar_get_dir | Environment variables for files and directories | 
| 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_ipaddress | Environment variables for internet and network-related values | 
| envvar_get_list | Environment variables containing lists | 
| envvar_get_logical | Get the value of an environment variable as a particular type | 
| envvar_get_numeric | Get the value of an environment variable as a particular type | 
| envvar_get_oneof | Get the value of an environment variable | 
| envvar_get_psv | Environment variables containing lists | 
| envvar_get_url | Environment variables for internet and network-related values | 
| envvar_get_uuid | Environment variables for UUIDs | 
| envvar_get_version | Get the value of an environment variable as a particular type | 
| 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 | 
| envvar_unset | Set, unset, and check environment variables |