Vacuumdb within crontab

Vacuumdb for postgres is best run in a cron. But when your database user needs a password, export it and the cron will run without a problem. Here is an example of a vacuumdb instance that exports the password and then does a full, quiet, and analyzing vacuumdb on the mydatabase database.

Clean, vacuum and analyze the tripplanning database
0 2 * * * export PGPASSWORD=mypassword && vacuumdb -f -q -z -U postgres -d mydatabase >> /var/log/messages 2>&1

Dates within crontab

If you want to add dates to backups or logs, like mythtvDB27062008.sql within crontab, do the following:

0 0 * * * /usr/bin/mysqldump -u mythtv -pPassword mythconverg > /mythtv/recordings/mythtvDB`date +%d%m%Y`.sql

The key is the backquotes around the `date +%d%m%Y` command. This will backup a MythTV MySQL database to a file like this: /mythtv/recordings/mythtvDB27062008.sql every night at midnight.