CRON
From DD-WRT Wiki
The crontab command, found in Unix and Unix-like operating systems, is used to schedule commands to be executed periodically. Dreamhost crontab wiki has a good explanation of how crontab works.
Crontab locations in DD-WRT
Crontab can be set in two locations on dd-wrt:
1. Either by putting your command in the /tmp/crontab file
echo ' * * * * * root /bin/date > /tmp/test.txt' >> /tmp/crontab
2. Or by putting a file in the /tmp/cron.d/ folder (eg. /tmp/cron.d/dosomething) that holds your command
echo '* * * * * root /bin/date > /tmp/test.txt' > /tmp/cron.d/date
Restarting Cron
After you modify/add the appropriate command you will need to restart cron in order for your changes to take effect. You can restart cron with the following command:
killall -9 cron; cron
Extras
You may wish to add this to your startup script, before any jobs are added. It will add clarity to your crontab file:
echo '# minute (0-59),' >> /tmp/crontab echo '# | hour (0-23),' >> /tmp/crontab echo '# | | day of the month (1-31),' >> /tmp/crontab echo '# | | | month of the year (1-12),' >> /tmp/crontab echo '# | | | | day of the week (0-6 with 0=Sunday).' >> /tmp/crontab echo '# | | | | | commands' >> /tmp/crontab
If you add this to your startup script, you will see this in your crontab file:
# minute (0-59), # | hour (0-23), # | | day of the month (1-31), # | | | month of the year (1-12), # | | | | day of the week (0-6 with 0=Sunday). # | | | | | commands