corrected CMD and updates as per advice
diff --git a/Dockerfile b/Dockerfile
index b1cc091..5003487 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,16 +1,15 @@
FROM ubuntu:14.04
-RUN apt-get update
-RUN apt-get install -y wget git curl
-RUN apt-get install -y --no-install-recommends openjdk-7-jdk
-RUN apt-get install -y maven ant
+
+RUN apt-get update && apt-get install -y wget git curl
+RUN apt-get update && apt-get install -y --no-install-recommends openjdk-7-jdk
+RUN apt-get update && apt-get install -y maven ant
RUN wget -q -O - http://pkg.jenkins-ci.org/debian/jenkins-ci.org.key | sudo apt-key add -
RUN echo deb http://pkg.jenkins-ci.org/debian binary/ >> /etc/apt/sources.list
-RUN apt-get update
-RUN apt-get install -y jenkins
+RUN apt-get update && apt-get install -y jenkins
RUN mkdir -p /var/jenkins_home && chown -R jenkins /var/jenkins_home
USER jenkins
-VOLUME /var/jenkins_home
+# VOLUME /var/jenkins_home
ENV JENKINS_HOME /var/jenkins_home
EXPOSE 8080
-CMD java -jar /usr/share/jenkins/jenkins.war
\ No newline at end of file
+CMD ["/usr/bin/java", "-jar", "/usr/share/jenkins/jenkins.war"]
\ No newline at end of file