Hello,
There is no file to see such thing. If you want to see what tasks are pending you can go to the UCSM toolbar and click on "Pending Activities" .
http://www.cisco.com/c/en/us/td/docs/unified_computing/ucs/sw/gui/config/guide/2-1/b_UCSM_GUI_Configuration_Guide_2_1/b_UCSM_GUI_Configuration_Guide_2_1_chapter_0100000.html#d21451e2778a1635
The whole UCS configuration and operation can be done by the GUI UCSM. All there you need is there, except some trick commands that can be perform by CLI.
Regards.
Richard.