These are the proces ID (.pid) files that are generated when the daemons are created:
/var/run/hadoop-yarn/yarn/yarn-yarn-resourcemanager.pid /var/run/hadoop-yarn/yarn/yarn-yarn-nodemanager.pid /var/run/hadoop-mapreduce/mapred/mapred-mapred-historyserver.pid
Without the proper permissions, the MapReduce daemons may not start or stop. The proper permissions are listed below.
drwxr-xr-x 2 yarn hadoop 4096 Oct 31 11:54 . drwxrwxr-x 3 yarn hadoop 4096 Oct 20 15:15 .. -rw-r--r-- 1 yarn hadoop 5 Oct 31 11:54 yarn-yarn-nodemanager.pid -rw-r--r-- 1 yarn hadoop 5 Oct 31 11:54 yarn-yarn-resourcemanager.pid -rw-r--r-- 1 mapred hadoop 5 Oct 31 11:54 /var/run/hadoop-mapreduce/mapred/mapred-mapred-historyserver.pid
