create a script file:
touch /tmp/oneshot_example
copy and paste the content from Run script session then run chmod +x /tmp/oneshot_example and sudo /tmp/oneshot_example
Raw example can be found here
#!/bin/bash
mkdir -p /tmp/foo/
# Setup /tmp/foo/setup-foo.sh
setup_foo_file=/tmp/foo/setup-foo.sh
touch $setup_foo_file
echo "#!/bin/bash" > $setup_foo_file
echo "echo \"Setting up foo ...\"" >> $setup_foo_file
echo "touch /tmp/foo-activated" >> $setup_foo_file
chmod +x $setup_foo_file
# Setup /tmp/foo/teardown-foo.sh
teardown_file=/tmp/foo/teardown-foo.sh
touch $teardown_file
echo "#!/bin/bash" > $teardown_file
echo "echo \"Tearing down foo ...\"" >> $teardown_file
echo "if [ -f /tmp/foo-activated ]; then" >> $teardown_file
echo " rm /tmp/foo-activated" >> $teardown_file
echo "else" >> $teardown_file
echo " echo \"Doesnt seem to be up: Skipping ...\"" >> $teardown_file
echo "fi" >> $teardown_file
chmod +x $teardown_file
# Setup /etc/systemd/system/foo.service
service_file=/etc/systemd/system/foo.service
touch $service_file
echo "[Unit]" >> $service_file
echo "Description=Setup foo" >> $service_file
echo "#After=network.target" >> $service_file
echo -en '\n' >> $service_file
echo "[Service]" >> $service_file
echo "Type=oneshot" >> $service_file
echo "ExecStart=/tmp/foo/setup-foo.sh" >> $service_file
echo "RemainAfterExit=true" >> $service_file
echo "ExecStop=/tmp/foo/teardown-foo.sh" >> $service_file
echo "StandardOutput=journal" >> $service_file
echo -en '\n' >> $service_file
echo "[Install]" >> $service_file
echo "WantedBy=multi-user.target" >> $service_file
systemctl daemon-reload
systemctl start foo.service
systemctl stop foo.service
rm /etc/systemd/system/foo.service