SHELL

copy file from host to docker container

docker cp foo.txt mycontainer:/foo.txt

copy file to docker container

docker cp foo.txt mycontainer:/foo.txt

copy a file from local machine to docker container

docker cp <Path in the local machine> <Container ID>:<Path of file inside the container>

Docker: Copying files from Docker container to host

for copy file from a container to the host use the command
docker cp <containerId>:/file/path/within/container /host/path/target

You can also use (part of) the Container ID. The following command is equivalent to the first
sudo docker cp 1b4a:/out_read.jpg .