Cron Jobs

cron(8) is a daemon that runs a command or script on a regular schedule as a specified user. Typically, the user who wishes to schedule a task manually creates a crontab(5) using syntax that can be perplexing to new Unix users. The FreeNAS® GUI makes it easy to schedule when you would like the task to occur.

NOTE: due to a limitation in FreeBSD, users with account names that contain spaces or exceed 17 characters are unable to create cron jobs.

Figure 4.1a shows the screen that opens when you click System → Cron Jobs → Add Cron Job:

Figure 4.1a: Creating a Cron Job

Table 4.1a summarizes the configurable options when creating a cron job.

Table 4.1a: Cron Job Options

Setting	Value	Description
User	drop-down menu	make sure the selected user has permission to run the specified command or script
Command	string	the full path to the command or script to be run; if it is a script, test it at the command line first to make sure that it works as expected
Short description	string	optional
Minute	slider or minute selections	if use the slider, cron job occurs every N minutes; if use minute selections, cron job occurs at the highlighted minutes
Hour	slider or hour selections	if use the slider, cron job occurs every N hours; if use hour selections, cron job occurs at the highlighted hours
Day of month	slider or month selections	if use the slider, cron job occurs every N days; if use day selections, cron job occurs on the highlighted days
Month	checkboxes	cron job occurs on the selected months
Day of week	checkboxes	cron job occurs on the selected days
Redirect Stdout	checkbox	disables emailing standard output to the root user account
Redirect Stderr	checkbox	disables emailing errors to the root user account
Enabled	checkbox	uncheck to disable the cron job without deleting it