LinuxQuestions.org - need help in detecting hardware failure through errors

Hi,
I am new to linux,
I have a bash script which triggers some tasks if any one if below hardware failures are detected.
1) if any hard disk bad sectors is detected
2) if any ethernet interface is failed
3) if any failure detected in nfs

lunux version in context is 2.6, red hat

my requirement:
I dont want to run any specific tools to find out these conditions as it is not feasible in my context. I just want to see the error logs from Operating system and detect above failures.

Questions:
1) Is my requirement a possible case?
2) Can I use /var/log/messages file alone to detect any of above these errors? or any more files need to be used?
3) I believe if #2 is possible then I can use grub to check the error messages and then trigger.
I needed exact error messages. Could some one suggest me links where I can find these errors?

I am trying to search through different sites for errors. Also let me know if there is any more suitable place to post this query.

thank you for your support.