The JAVA_TOOL_OPTIONS Environment Variable

In many environments the command line is not readily accessible to start the application with necessary command-line options. This often arises with applications that use embedded VMs (meaning they use the Java Native Interface (JNI) Invocation API to start the VM), or where the startup is deeply nested in scripts. In these environments the JAVA_TOOL_OPTIONS environment variable can be useful to augment a command line.

When this environment variable is set, the JNI_CreateJavaVM function (in the JNI Invocation API) prepends the value of the environment variable to the options supplied in its JavaVMInitArgs argument.

This environment variable allows you to specify the initialization of tools, specifically the launching of native or Java programming language agents using the -agentlib or -javaagent options. In the following example the environment variable is set so that the HPROF profiler is launched when the application is started:

$ export JAVA_TOOL_OPTIONS="-agentlib:hprof"

This variable can also be used to augment the command line with other options for diagnostic purposes. For example, you can supply the -XX:OnError option to specify a script or command to be executed when a fatal error occurs.

Since this environment variable is examined at the time the JNI_CreateJavaVM function is called, it cannot be used to augment the command line with options that would normally be handled by the launcher, for example, VM selection using the -client option or the -server option.