History of commands?

Is there any way to find which commands have been executed between 2 specific dates (like 2 to 3 months period)?

I can use the history command, but I have powered the system on/off.

Is this possible? And how?

Not by default. You should install the psacct (Process Accounting) utilities to get this functionality.

sudo apt-get install acct

The ubuntu package turns on process accounting as part of the install. It provides the following commands:

• ac - print statistics about users’ connect time
• lastcomm - print out information about previously executed commands.
• sa - summarizes accounting information
• accton - turns process accounting on or off

No, not possible with the default install. If you care about the next 2 - 3 months, it is possible to set something up to track this, but not for the prior 2-3 months.