When MDB attaches to a running user process, the process is stopped and remains stopped until one of the continue dcmds is applied, or the debugger quits. If the –o nostop option is enabled prior to attaching the debugger to a process with –p or prior to issuing an ::attach or :A command, MDB will attach to the process but not stop it. While the process is still running, it may be inspected as usual (albeit with inconsistent results) and breakpoints or other tracing flags may be enabled. If the :c or ::cont dcmds are run while the process is running, the debugger will wait for the process to stop. If no traced software events occur, the user can send an interrupt (^C) after :c or ::cont to force the process to stop and return control to the debugger.
MDB releases the current running process (if any) when the :R, ::release, :r, ::run, $q, or ::quit dcmds are executed, or when the debugger terminates as the result of an EOF or signal. If the process was originally created by the debugger using :r or ::run, it will be forcibly terminated as if by SIGKILL when it is released. If the process was already running prior to attaching MDB to it, it will be set running again when it is released. A process may be released and left stopped and abandoned using the ::release -a option.