ccglue is a complementary tool to cscope and ctags. The tool builds a cross-reference symbol database from cscope (and ctags) databases that can be used to display dependency-graphs (aka call-trees, code flow). Visualization can be done with the Vim CCTree plugin or the built-in stand-alone command-line tracer.
The OATH Toolkit makes it easy to build one-time password authentication systems. It contains shared libraries, commandline tools, and a PAM module. Supported technologies include the event-based HOTP algorithm (RFC4226) and the time-based TOTP algorithm (RFC6238). OATH stands for Open AuTHentication, which is the organization which specifies the algorithms. For managing secret key files, the Portable Symmetric Key Container (PSKC) format described in RFC6030 is supported.
GNU Recutils is a set of tools and libraries to access human-editable text-based databases called recfiles. A recfile contains data structured as a sequence of records. The rec format supports data integrity with the usage of record descriptors (keys, mandatory fields, field types, etc.) as well as the ability of record fields to refer to other records. Despite its simplicity, recfiles can be used to store medium-sized databases. The GNU recutils suite comprises a texinfo manual describing the Rec format, a C library (librec) providing a rich set of functions to access rec files, a set of C utilities that can be used in shell scripts and in the command line to operate on rec files, and an Emacs mode (rec-mode).
Clzip is a lossless data compressor with a user interface similar to the one of gzip or bzip2. Clzip decompresses almost as fast as gzip and compresses more than bzip2, which makes it well suited for software distribution and data archiving. Clzip uses the lzip file format; the files produced by clzip are fully compatible with lzip-1.4 or newer, and can be rescued with lziprecover. Clzip is, in fact, a C language implementation of lzip, intended for embedded devices or systems lacking a C++ compiler. The lzip file format is designed for long-term data archiving and provides very safe integrity checking.
Upmf is a source-based package manager written almost completely in Scheme. The user is able to search, build, and remove packages. Since Scheme through GUILE is very extensible, the user can customize the procedures, or even exchange them with his own, if wanted. Packages are stored in their own self-contained directories and are incorporated into the filesystem with help of GNU Stow.
The GNU Autoconf Archive is a collection of more than 450 macros for GNU Autoconf. They can be re-used without imposing any restrictions on the licensing of the generated configure script. In particular, it is possible to use them in configure scripts that are meant for non-free software.