Software → Operating Systems
File Descriptor
A small integer handle used by a process to refer to an open file, socket, pipe, or device.
Motivation
File descriptor solves the problem of giving processes a uniform handle to files, sockets, pipes, and devices.
Where it fits
File Descriptor belongs to operating systems and I/O.
Mental model
A process does not manipulate every resource directly; it uses small numeric handles managed by the OS.
Common mistakes
- Thinking file descriptors are only for disk files.
- Forgetting to close descriptors in long-running processes.
Related concepts
File Descriptor connects to process, pipe, socket, disk I/O, and virtual file system.