Example of using a systemd .path unit

systemd-path-unit.txt

# Notice the `[Install]` section in the `.path` file instead of the `.service` file.
#  This is important for packaging.

------------------------------------------------
/lib/systemd/system/package-name.path
------------------------------------------------
[Path]
PathChanged=/etc/package-name.config

[Install]
WantedBy=default.target

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/lib/systemd/system/package-name.service
------------------------------------------------
[Unit]
Description=package-name
After=network-online.target
Requires=network-online.target

[Service]
Type=simple
ExecStart=/opt/package-name/package-name -config=/etc/package-name.config

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# Note: For debian packaging, as of March 2017, the path unit is not natively
#  supported, as the service unit is. An interim solution is specified here:
#  http://askubuntu.com/questions/885439/what-is-the-proper-way-to-package-path-unit-files

Never got it to work with these instructions, if someone manages to get here through a search engine, I recommend https://blog.andrewkeech.com/posts/170809_path.html