List Postfix Default Values  

To get a detailed list of defaults for Postfix, simply:

postconf -d

However, this may be a bit unweildy, so narrowing it down with a pipe to grep will help, as in:

postconf -d | grep myhostname
List Postfix NON-Default Values  

To get a list parameters that have been changed, this will include parameters that are default but configured within, simply:

postconf -n

Again, you can narrow down the list by piping to grep, as in:

postconf -n | grep myhostname
List Upgradeable Packages  

Have you ever just wanted a list of packages that can be upgraded, in a system with a GUI it's super easy, but in a headless or text based system it seams you have to start the upgrade to get the list.  The following command will simply list the upgradeable packages:

aptitude search '~U'

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