Need help specifying args in rc.conf for a service

[Scott]

Hi all,

I posted this on the forums and was unsuccessful so I thought I'd try here:

I've been struggling to pass additional arguments to the Prometheus 
node_exporter daemon in /etc/rc.conf.

The help for node_exporter provides an example argument (mount points to 
ignore) as:

--collector.filesystem.ignored-mount-points="^/(dev)($|/)"
                                Regexp of mount points to ignore for filesystem collector.

The rc script says to use the _args variable to specify arguments to 
node_exporter:
# node_exporter_args (string):          Set extra arguments to pass to 
# Default is "".

Adding the line:

node_exporter_args="--collector.filesystem.ignored-mount-points=\"^/(dev)($|/)\""

to /etc/rc.conf and running sh -x /usr/local/etc/rc.d/node_exporter start 
results in:

+ limits -C daemon su -m nobody -c 'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)($|/)""'
Illegal variable name.

It was suggested on the forum to try:
node_exporter_args='--collector.filesystem.ignored-mount-points="^/(dev)(\$|/)"'
# OR
node_exporter_args="--collector.filesystem.ignored-mount-points='^/(dev)($|/)'"

However with the first suggestion I got:
limits -C daemon su -m nobody -c 'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)(\$|/)""'
Badly placed (.

and with the second I got:
eval $' limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points=\'^/(dev)($|/)\'"\''
eval: 1: Syntax error: "(" unexpected

Can anyone please help?

Thanks,
Scott