Sample code for auditing tasks

Sometimes we need to check info on certain attribute, content, templates, etc. for their existence or shared/unshared  or status, etc. For such cases, you can write your own utility to do batch audit operations. I am listing sample code for few cases:

1. Any asset of a particular asset type with a name exists or not?

2. If a particular asset is present in site or not?
3. Check all variables of a particular asset

Disclaimer: Any sample code on this blog is not officially recommended, use at your own risk.