A dbx session runs from the time you start dbx until you quit dbx.You can debug any number of programs in succession during a dbx session.
To quit a dbx session, type quit at the dbx prompt.
(dbx) quit
When you start dbx and attach it to a running process y providing the process ID option, the process survives and continues when you quit the debugging session. dbx performs an implicit detach before quitting the session.