Given a directory of text files, pannote will go and index those files using xapian. It uses an English stemmer. Then you give it a term and it will find all matching files. Each time it runs, it reindexes everything and deletes the database.
$ pannote --help
Usage: pannote [OPTIONS] DIRECTORY TERM
A simple program that indexes a directory of text files and allows you to
search it
Options:
-0, --print0 separate matches with a null byte in output
--help Show this message and exit.
Pannote works really well with Facebook's PathPicker.
$ pannote /path/to/notes "isomorphic" | fpp
$ brew install xapian --with-python
$ pip install pannote
$ dnf install xapian-bindings-python
$ pip install pannote
$ apt-get install python-xapian
$ pip install pannote
GPLv3