What are file descriptors and inode? How do they differ?

A file descriptor is an integer identifier that the operating system allocates to a process for accessing an open file or other input/output resource (e.g., a socket). The process uses the file descriptor to read, write, and manage the file.

An inode is a data structure in the file system that stores metadata about a file: access rights, owner, size, modification time, and pointers to the blocks containing the file's content. Each inode is unique within the file system.

Main differences:

• An inode describes a file at the file system level.
• A file descriptor is a 'handle' for the process to work with the file through the OS.

For example, one inode can have multiple file descriptors if the file is opened in multiple processes.