How to execute Linux shell commands in Docker

docker run ubuntu sh -c 'cat /data/a.txt > b.txt'

Dockfile
FROM vertigomedia/ubuntu-jdk8
RUN touch /root/app_start.sh
RUN echo "#!/bin/bash" > /root/app_start.sh
RUN echo "echo 111" >> /root/app_start.sh
RUN chmod a+x /root/app_start.sh
ENV TZ 'Asia/Shanghai'
ENV APP_FILE /root/app_start.sh
EXPOSE 8889
CMD $APP_FILE
#ENTRYPOINT ["/bin/sh", "-c", "$APP_FILE"]

container.sh
#!/bin/bash
echo "test xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
java -jar -Xms500m -Xmx500m -Dspring.profiles.active=test-docker-1 /root/app.jar

docker run -itd \
 --name test_container \
 --hostname test_container \
 --net test_net --ip 170.170.1.199 \
 --volume /root/container.sh:/root/app_start.sh \
 --volume /opt/test-1.0.0-SNAPSHOT.jar:/root/app.jar \
 --privileged=true \
 test:123 /bin/bash -c 'sh /root/app_start.sh'