Isn't it safer to create a credentials file and give it the appropriate chmod?
http://www.12factor.net/config
112 6725 0.1 36.7 1965924 1411164 ? SLl May03 37:11 /usr/lib/jvm/java-7-openjdk-amd64//bin/java -Xms1g -Xmx1g -Xss256k -Djava.awt.headless=true -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSInitiatingOccupancyOnly -XX:+HeapDumpOnOutOfMemoryError -Delasticsearch -Des.pidfile=/var/run/elasticsearch.pid -Des.path.home=/usr/share/elasticsearch -cp :/usr/share/elasticsearch/lib/elasticsearch-0.90.0.jar:/usr/share/elasticsearch/lib/:/usr/share/elasticsearch/lib/sigar/ -Des.default.config=/etc/elasticsearch/elasticsearch.yml -Des.default.path.home=/usr/share/elasticsearch -Des.default.path.logs=/var/log/elasticsearch -Des.default.path.data=/var/lib/elasticsearch -Des.default.path.work=/tmp/elasticsearch -Des.default.path.conf=/etc/elasticsearch org.elasticsearch.bootstrap.ElasticSearch