I wanted to start doing regular maintenance to my linux servers. They all run CentOS 4 or 5. I have 3 DNS (Bind) 1 Data server being MySQL, and 2 web hosting servers that run LAMP mostly. I am not real savy on the shell and I wish I knew it like I do like in the old DOS days. What things would you suggest to keep up with regular maintenance to prevent problems and keep them efficient and how often would you run them? I usally manage the servers via Webmin and ssh to them. If there is commands I need to familiar myself with along with your suggestions, please tell me what they are so I can really study up on them. Maybe I can even setup a cron job to preform these tasks as well.

Setting up cron jobs is ideal
Having data backed up is essential
Checking the file system integrity using one of many freely available programs such as tripwire or others that make checksums on the system and periodically (thru cron) run and ensure nothings has changed.

Best I can do.