afni.nimh.nih.gov

With 9 conditions, there are 36 possible pairwise contrasts; however, among them there are only 8 independent ones. So, any set of 8 independent pairwise contrasts would be fine to obtain the conventional "omnibus" inference in this case. For example, you can also go with

-gltsym 'SYM: +a1 -a2 \ +a1 -a3 \ +a1 -a4 \ +a1 -a5 \ +a1 -a6 \ +a1 -a7 \ +a1 -a8 \ +a1 -a9'

Gang