Sed, a powerfull mini-language from the 70s

The article explores sed as more than a simple text-editing command, revealing it to be a full mini-language with control flow, loops, and memory via pattern and hold spaces. It demonstrates progressively advanced techniques from basic line filtering and substitution to multi-line processing with loops and sliding window patterns. The key insight is that sed operates as a stream-processing machine capable of buffer manipulation, making it a surprisingly powerful programming tool from the 1970s.