What is the Unix "everything is a file" philosophy?

In Unix/Linux nearly every I/O resource — devices, pipes, sockets — is exposed as a "file": a byte stream you open, read, write, and close.

Because the same handful of operations work on all of them, programs need no device-specific code, can be chained together with pipes, and have permissions applied to them uniformly.

A file = sequence of bytes

"Everything is a file" includes:

• Disk (obviously)
• Keyboard
• Mouse
• Display
• Network connections
• Shared memory
• Pipes between processes

Benefits:

• Single, consistent interface for all I/O
• Programs don't need device-specific code
• Easy to combine programs (pipelines)
• Permissions work uniformly

File operations: open, read, write, close, seek - work on ALL these "files."

Go deeper:

• Everything is a file (Wikipedia) — file descriptors, /dev, and procfs/sysfs unifying devices and kernel state behind file operations.