monthly, monthly.conf —
monthly maintenance
The /etc/monthly script is normally run in the morning
  of the 1st of every month, on a NetBSD system. Note:
  this is disabled (commented out) in the default root's
  crontab(5) file. The
  /etc/monthly.conf file specifies which of the standard
  monthly services are performed.
There are currently no monthly tasks.
  - /etc/monthly
- monthly maintenance script
- /etc/monthly.conf
- monthly maintenance configuration
- /etc/monthly.local
- local site additions to /etc/monthly
The /etc/monthly.conf file appeared in
  NetBSD 1.3.