Schedule a job on the 2nd Tuesday of the month

Cron doesn't have the flexibilty to allow you to schedule a script on, for example, the second Tuesday of every month. However this can be achieved using some date checking in your crontab entry, e.g.

 00 09 * * 2 [ $(date +\%d) -gt 7 ]&& [ $(date +\%d) -lt 15 ] && /run/your/script

The second Tuesday of the month will fall in a date range of the 8th to the 14th. The command will run at 9:00 every Tuesday but then check whether the day is in the range 8th - 14th before executing the script