Lwpp is a lightweight text file preprocessor. Lwpp reads a file as input and writes sections of the file as output, based on certain conditions embedded in the file as preprocessor directives. Lwpp is meant mostly to emulate the C preprocessor's '#if[n]def ... #endif' functionality, but without any of cpp's other C-oriented features (including macro expansion), and without putting extra newlines into the output. Lwpp uses the environment as a dictionary of symbol definitions, so you can use the value of regular environment variables (such as HOME or HOST) as symbol definitions without having to define them again on the command line.
logsurfer is a log checking/auditing tool similar to swatch and logcheck but with the capability of handling multi-line messages and dynamically adapting the ruleset. It is written in portable C, well documented, fast, and flexible. It works on any textfile or stdin, can be run at intervals or continuously, and has timeouts and resource limits.