head -c 1 </dev/urandom >/dev/shm/1B
head -c $((8*1024*1024-1)) </dev/urandom >/dev/shm/8MB-1
head -c $((8*1024*1024+1)) </dev/urandom >/dev/shm/8MB+1
head -c $((128*1024*1024)) </dev/urandom >/dev/shm/128MB
head -c $((4*1024*1024*1024)) </dev/urandom >/dev/shm/4GB
head -c $((30*1024*1024*1024)) </dev/urandom >/dev/shm/30GB

head -c 1 </dev/urandom >/1B
head -c $((8*1024*1024-1)) </dev/urandom >/8MB-1
head -c $((8*1024*1024+1)) </dev/urandom >/8MB+1
head -c $((128*1024*1024)) </dev/urandom >/128MB
head -c $((4*1024*1024*1024)) </dev/urandom >/4GB
head -c $((30*1024*1024*1024)) </dev/urandom >/30GB