There are two ways to use prof:
cc -p -o myprog myprog.c
myprog (generates mon.out)
prof myprog mon.out
OR
cc -o myprog myprog.c
pixie -o myprog.pixie myprog (generates myprog.Addrs)
myprog.pixie (generates myprog.Counts)
prof -pixie myprog (reads myprog.Addrs myprog.Counts
In both cases, the results are sent to Standard Output.