Oracle Database Discussions

My this post may seem some child's play to some people however i am looking for help seriously since i am trapped now...... We have enabled audit log on our oracle database server and we have intentionally (obviously after a long discussion) set its audit_trail variable to OS; now our oracle is dumping its log files on our Operating system. We are working in unix environment.
My logs have started growing like hell well that i wish to discuss later (may be some other thread) now i am in trouble just because of the format of the logs. I have almost collected more than 0.7 million files and of approximately of 3 formate space (wooops); but i can afford this space as well if it gives something meaningful to me. Oracle has started behaving really strange; it has started creating files with following foramte:
aud_xxx (where xxx is PID number(Process id number of unix processes))
Now i don't have any idea where to find my required infor such as: which user did wat when how nothing simply i have been provided a human readable file with unknown file formate and unkown structure.
I shall be thankful if any one out here can provide me help in this reagrd. If some one as any idea how does oracle write logs into its log files and wat type of file should i look for - say for example if i have to see which user logged when and wat he did during that session (basically a trail).

Thanx in advance