execline is a very light, non-interactive scripting language, which is similar to a shell. Simple shell scripts can be easily rewritten in the execline language, improving performance and memory usage. execline was designed for use in embedded systems, but works on most Unix flavors.
s6-portable-utils is a set of tiny general Unix utilities, often performing well-known tasks such as cut and grep, but optimized for simplicity and small size. They were designed for embedded systems and other constrained environments, but work everywhere. Other sets of small utilities are usually system-specific; for instance, the (otherwise excellent) BusyBox project only works on Linux.
skadns is an asynchronous DNS client library. It was designed for simplicity of use and light resource usage, and can even be used on an embedded system. Unlike other DNS client libraries, skadns leaves the asynchronous work to a forked process, making the client API easy to understand and use.
skalibs is a set of general-purpose, low-level C libraries, all in the public domain. It can replace or hide the standard C library to some extent. It is designed to allow building of small static binaries. It is used in building all skarnet.org software, including execline and s6.
ucspi-ipc implements D. J. Bernstein's UCSPI protocol in the Unix domain, making it trivial to set up clients or servers on Unix sockets. ucspi- ipc comes with utilities using credential passing on Unix sockets, which are designed to act like a fine-grained and efficient sudo without the need for setuid programs.
Re: Comments and alternatives > The only thing auto* tools have good is that they work. Not even. I am a diet libc (http://www.fefe.de/dietlibc/) user, and I find it very diffic...