Then, stick 001 at the beginning (this is not counted as a command) and convert to decimal. Then, write that number of exclamation points.
Cat program (one time input)
The BF program ,. would have 108 exclamation points.
Cat program (looped)
The BF program ,[.,] would have 7,079 exclamation points.
The BF program ,.[.] would have 55,719 exclamation points.
To print "Hello, world!" you would need 24,866,256,684,781,338,733,321,022,194,929,619,017,923,951,399,467,222,375,071,721,694,990,877,932,162,871,254,860,804 exclamation points.