The following modules are provided by NAG as a partial interface to the operating system facilities defined by ISO/IEC 9945-1:1990 Portable Operating System Interface (POSIX) -- Part 1: System Application Program Interface (API) [C Language].
| f90_unix_dir | Directories and Files |
| f90_unix_dirent | Directory Reading |
| f90_unix_env | Environment |
| f90_unix_errno | Error Codes |
| f90_unix_file | File Characteristics |
| f90_unix_io | Input/Output (incomplete) |
| f90_unix_proc | Processes |