Cron Jobs

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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

Cron1f.png

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
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