# Class Uq_engines.copier

    class copier : copy_task -> Unixqueue.event_system -> [unit] engine

This engine copies data between file descriptors as specified by the `copy_task` argument.

The task is done when all input descriptors are at EOF. See the description of `copy_task` for details, especially whether the descriptors are closed or not.

On error or abort, the descriptors are only closed if they had been closed on regular EOF.

The semantics of the engine is undefined if one of the descriptors is not stream-oriented.