use docker exec to change /etc/hosts error

[Jam-Lin]

hello, i use docker exec 1ebea17823f3 echo test >> /etc/hosts to change the container /etc/hosts, but i find that the container hosts do not change. it change the vm /etc/hosts.

[thaJeztah]

I think this is expected, and not a bug in docker; basically what your doing is;

(docker exec 1ebea17823f3 echo test) >> /etc/hosts

(Added the parentheses to illustrate the problem) Basically, the echo test runs inside the container, but the output is returned to the host (vm) and added to /etc/hosts of the VM.

Try it this way, so that both the "echo" AND the >> /etc/hosts take place inside the container;

docker exec 1ebea17823f3 /bin/sh -c "echo test >> /etc/hosts"

I'm going to close this issue, because it's not a bug, but I hope the above explanation helps you further!