Uptime since boot excluding sleep for osx yosemite?
As far as I know there is no simple command executed in Terminal to get your desired result.

Here is an example for a workaround to get the uptime and the sleep time(s):

uptime &amp;&amp; pmset -g log|grep 'date'|grep -E ' Wake | Sleep '|grep -v 'Dark Wake'


with date: dd/mm/yy (example: 23/07/15)

Example (10.9.5 Virtual Machine): 

machinename:~ user$ uptime &amp;&amp; pmset -g log|grep '23/07/15'|grep -E ' Wake | Sleep '|grep -v 'Dark Wake'
14:59  up  1:09, 3 users, load averages: 0.58 0.47 0.51
23/07/15 13:51:39 GMT+2  Sleep                  Software Sleep pid=90: Using AC                                             10 secs   
23/07/15 13:51:49 GMT+2  Wake                   Wake [CDNVA] due to power-button/User: Using AC                             149 secs  
23/07/15 13:54:18 GMT+2  Sleep                  Software Sleep pid=90: Using AC                                             91 secs   
23/07/15 13:55:49 GMT+2  Wake                   Wake [CDNVA] due to power-button/User: Using AC                             1872 secs 
23/07/15 14:27:01 GMT+2  Sleep                  Software Sleep pid=90: Using AC                                             7 secs    
23/07/15 14:27:08 GMT+2  Wake                   Wake [CDNVA] due to power-button/User: Using AC


Now do the math and calculate the non-sleep uptime. (6540 secs - 108 secs = 6432 secs).

Depending on your operating system and the hibernation mode you set, you may have to alter the grep part in the above command. Check pmset -g log for the appropriate strings. You also may omit the ' Wake ' part of the command to simplfy the output.