# Definition of a file

## Definition of a file¶

A file is an unstructured sequence of characters stored in a file.

• sequential access (one reads the characters one after the other)

• or direct access (one accesses the character at a given address).

Under Unix, everything is file (or almost). A file can contain characters, but also binary (machine) code. However, the system makes a difference on the kinds of files it handles. He thus knows:

• Ordinary files (files) used to store programs or data

• Directories that allow you to group files

• Character files (characters) as a keyboard input

• Block access files (blocks) as a hard disk

• Files that contain references to another volume and are called symbolic links (links)

• Pipes (pipes) that connect two processes, for example by connecting the standard output of one process to the standard input of another

• Files that allow access to remote files on a network (socket)