grep is on every Unix machine and handles one file at a time. ripgrep (rg)
is built for a source tree: it walks directories in parallel, skips what
.gitignore skips, and uses a regex engine that cannot go exponential. Both
match lines against a pattern; the differences that matter are in what they
search by default and how fast they get through a tree.
./script.sh, exec ./script.sh, . ./script.sh and ./script.sh & look
alike and do four different things. What differs each time is whether a new
process exists, whose environment changes, what $? holds afterwards, and
who gets the terminal’s signals.
LogWisp began as a way to stop doing the same thing every morning: SSH into
each server, tail -F a file, grep it, repeat on the next one. The platforms
that solve this are sized for fleets; my servers are a handful, their traffic
is low, and I wanted one static binary that streams, filters and forwards logs
and asks for nothing else. This is how that binary found its shape.