HERA-B higher-level triggers: architecture and software

HERA-B will be studying CP-violation in the B-system in a high-rate hadronic environment. To accomplish this goal, HERA-B needs a sophisticated data acquisition and trigger system. Except for the first level, all trigger levels are implemented as PC-farms, running the Unix-like operating system, Linux, thus blurring the sharp border between online and offline application software. The hardware architecture and software environments are discussed.