I have tried
sudo sh -c 'echo 3 > /proc/sys/vm/drop_caches'
sudo echo 3 > /proc/sys/vm/drop_caches
echo 3 > /proc/sys/vm/drop_caches
echo 3 | sudo tee /proc/sys/vm/drop_caches
and a bunch of other variations but with every try I get
bash: /proc/sys/vm/drop_caches: Permission denied
How do I clear the ram used for buffers/cache in my centos6 openvz container?
It seems like the only way to do what I need is to reboot the container.