Using the debugger is recommended when running a small number of processes. If you supply the PvmTaskDebug flag in the function pvm_spawn(...), it will attempt to start each task in a separate window under the control of a debugger. The same effect can be achieved by clicking on the PvmTaskDebugbutton in the Spawn subwindow in xpvm. Under LINUX the default debugger is gdb. The default debugger can be changed by setting the PVM_DEBUGGER environment variable.