These events occur after a dlopen()() call or a dlclose()() call succeeds. A dlopen()() call or dlclose()() call can cause more than one library to be loaded. The list of these libraries is always available in the predefined variable $dllist. The first shell word in $dllist is a “+” or a “-”, indicating whether the list of libraries is being added or deleted.
lib-path is the name of a shared library. If it is specified, the event occurs only if the given library was loaded or unloaded. In that case, $dlobj contains the name of the library. $dllist is still available.
If lib-path begins with a /, a full string match is performed. Otherwise, only the tails of the paths are compared.
If lib-path is not specified, then the events always occur whenever there is any dl-activity. In this case, $dlobj is empty but $dllist is valid.