Dockerfile to add multiple line to file - it is useful to "docker cp" a conf file

gistfile1.txt

$ cat Dockerfile 
FROM centos:7
RUN mkdir /work
RUN echo <<< EOL\
 line 1, \
 line 2, \
 line 3, \
 line 4 \
 line ... \
 EOL >> /etc/myconfig.conf;

# Build the container and tag it then:

$ docker cp $(docker ps -a -q):/etc/myconfig.conf /tmp