gnu.hylafax implements the HylaFAX client network protocol in pure Java. With it, Java applications can access a HylaFAX server in various ways, such as queueing FAX jobs, checking server/job status, and retrieving FAX files. The gnu.hylafax distribution also includes gnu.inet.ftp, a pure Java implementation of FTP client protocol (RFC0959).
GNUlpr version 1.0 is a complete printing system based on LPR, and provides support for printer-specific options, GUI tools, and autoconfiguration. The 1.1 tree is a completely re-thought printing system. Rather than creating an all-powerful spooling daemon, it constructs a pipeline of "filter" programs to perform tasks (spooling, data stream type conversion, authentication, network protocols, etc.).
GNUstep is a cross-platform, object oriented environment composed of frameworks, tools, and servers (daemons). It is very similar to the Cocoa frameworks from Apple, and tries to maintain compatibility with Cocoa wherever it is desired and possible. The frameworks provide classes for containers, distributed objects, object archiving, file management, text system, font management, image composition, WYSIWYG PostScript graphics, and more.
GnuTLS is a secure communications library implementing the SSL, TLS, and DTLS protocols and technologies around them. It provides a simple C language application programming interface (API) to access the secure communications protocols, as well as APIs to parse and write X.509, PKCS #12, OpenPGP, and other required structures. It is intended to be portable and efficient with a focus on security and interoperability.
GPP is a general-purpose preprocessor with customizable syntax, suitable for a wide range of preprocessing tasks. Its independence from any programming language makes it much more versatile than cpp, while its syntax is lighter and more flexible than that of m4. The syntax is fully customizable, which makes it possible to process text files, HTML, or source code equally efficiently in a variety of languages.
GQL is a C++ library for generic SQL database access, modeled after JDBC (Java Database Connectivity). It includes drivers for PostgreSQL, MySQL, and SQLite, and includes GQL-Shell, an interactive database terminal called that features command-line editing, history, and database metadata (schema) browsing.
Grok is a library of Java components for performing various natural language tasks. These include several preprocessing tasks, chart parsing, a large categorial grammar for English (induced from the Penn treebank), and some knowledge representation components (basic coreference, salience tracking, etc.). The library also has a companion kit which provides a GUI interface to the components, several of which are implementations of interfaces in the Quipu OpenNLP API.