A remote file system application program interface (API) for a remote file system installable file system (IFS) and operating system file system. The remote file system API enables a file content searching program that performs a search on a mapped remote drive to pass the file system path to search and the search criteria regular expression pattern to the remote system for searching and the results are returned to the client system in an IO stream. Such an application program interface is useful in the area of network file systems, network mapped drives, and file content searching programs such as a global regular expression processor (grep).