first boot

Not sure what you are asking here. If you have been running it without a re-boot all that time and you want to find out how long you have been up, the answer is yes, there is a way.

Launch Terminal and type "uptime". (without quotes)

 

The Unix side of OS X keeps track of logins and reboots in the file /var/log/wtmp. The 'last' command reads this file and prints information in human-readable form. Only problem? Every month OS X cleans out the log file and starts a new one. It saves the previous 5 months of wtmp files, so if the date you're looking for is in the last 5 months, you should be in luck. Here's what you'll need to do:

Open up Terminal. First you want to get a listing of available old wtmp files:

Code:

ls -l /var/log/wtmp*

Mine looks like this:

Code:

-rw-r--r--  1 root  admin  936 18 Nov 09:34 /var/log/wtmp
-rw-r--r--  1 root  admin  496 31 Oct 23:48 /var/log/wtmp.0.gz
-rw-r--r--  1 root  admin  251 24 Sep 08:01 /var/log/wtmp.1.gz
-rw-r-----  1 root  admin  750 30 Aug 13:16 /var/log/wtmp.2.gz
-rw-r-----  1 root  admin  295 30 Jun 23:12 /var/log/wtmp.3.gz
-rw-r--r--  1 root  admin  199 31 May 13:06 /var/log/wtmp.4.gz

(I'm missing one from the end of July because I moved on August 1st, so the machine wasn't running to do that little bit of housekeeping then)

Find the oldest file, and unzip it:

Code:

sudo gunzip /var/log/wtmp.4.gz

(replace the 4 with the number of your oldest one).

Finally, run 'last' on that file to find the reboot entry you wanted:

Code:

last -f /var/log/wtmp.4 reboot

To see everything logged in that file, omit the 'reboot' part. Or to see it for the current month, omit everything but the 'last' command.

Hope this helps!