3.4.1. The UNIX philosophy: Everything is a file

Most of the resources are accessible through "special files" in the filesystem. For example:

• /dev/da*, /dev/ad* -- the hard disks and partitions
• /dev/tty*, /dev/pty* -- terminals and pseudo-terminals
• /dev/lpt0 -- the printer
• ...

Other special files:

• named pipes (FIFO): allow communication between processes
• unix sockets: another form of interprocess communication
• links: pointers to other files/directories in the filesystem

The special files above can be manipulated like any other file: open, read, write, close.

Additionally, some special filesystems exist which contain "virtual" files - for example, /proc in Linux.