Java not installed or JAVA_HOME environment variable not set

Error when Java is not installed or the path is not set.

If Java is not installed or if OpsCenter cannot find JAVA_HOME, you may see an error such as:

/usr/share/datastax-agent/bin/datastax-agent: line 98:exec: -X: invalid option
 exec: usage:  exec [-cl ] [-a name ] [ command [arguments ... ]] [redirection ... ]

To correct this problem, install Java or set JAVA_HOME:export JAVA_HOME =<path_to_java>