epoll_data - Linux


epoll_data is a Linux command-line utility used to interact with the Linux epoll event notification facility. It allows users to create epoll instances, add and remove file descriptors to these instances, and wait for events to occur on registered file descriptors.


epoll_data [--help] [--version] [--create] [--add <fd> <events>] [--delete <fd>] [--wait <timeout>]


  • –help: Print usage information.
  • –version: Print the version of the utility.
  • –create: Create a new epoll instance.
  • –add: Add a file descriptor to an epoll instance and specify events to watch for.
  • –delete: Delete a file descriptor from an epoll instance.
  • –wait: Wait for events to occur on registered file descriptors, with an optional timeout value (in milliseconds).


Create an epoll instance and add a file descriptor:

epoll_data --create --add 0 EPOLLIN

Wait for events on the file descriptor for 5 seconds:

epoll_data --wait 5000

Delete a file descriptor from the epoll instance:

epoll_data --delete 0

Common Issues

  • Make sure that the file descriptor being added is valid and not already closed.
  • Use appropriate event flags when adding a file descriptor. For example, use EPOLLIN for input events and EPOLLOUT for output events.
  • Handle errors when adding or deleting file descriptors. These errors can indicate invalid file descriptors or incorrect usage of the epoll_data utility.


epoll_data can be integrated with other commands or tools to build advanced event-driven applications. For example, it can be used to implement custom event loops for network servers or asynchronous I/O operations.

Related Commands

  • epoll_ctl
  • epoll