Hidden file and hidden directory
In computing, a hidden directory or hidden file is a directory (folder) or file which file system utilities do not display by default. They are commonly used for storing user preferences or preserving the state of a utility and are frequently created implicitly by using various utilities. Usually the intent is to not "clutter" the display of the contents of a directory with files the user did not create.
Unix and Unix-like environments 
In Unix-like operating systems a file or directory that starts with a period/full stop character (for example: /home/user/.config) is to be treated as hidden, that is the
ls command does not display them. Use
ls with the flag
ls -a) to include them. Midnight Commander shows them by default. The Nautilus file manager also excludes from the display filenames contained in .hidden in each directory (the keyboard shortcut Ctrl-h enables the display of hidden files).
The notion that filenames preceded by a '.' should be hidden is the result of a software bug in the early days of Unix. When the special '.' and '..' directory entries were added to the filesystem, it was decided that the ls command should not display them. However, the ls program was mistakenly written to exclude any file whose name started with a '.', rather than only files named '.' or '..'.
Mac OS X 
In addition to the "dotfile" behaviour, files with the "Invisible" attribute are hidden in Finder, although not in
ls. The "Invisible" attribute can be set or cleared using the
SetFile command; for example, invoking
SetFile -a V jimbo will hide the file "jimbo". Starting in Mac OS X Snow Leopard, the
chflags command can also be used; for example,
chflags hidden jimbo will hide the file "jimbo".
DOS and MS Windows 
In MS-DOS and other DOS systems, file directory entries include a Hidden File attribute which is manipulated using attrib command. Use the command line command
dir /ah to display the files with the attribute of hidden.
Malicious programs can use this functionality to hide their presence.
- "Configuring X: What are all those dotfiles for anyway?". Red Hat, Inc. 2002-11-02. Retrieved 2012-02-13.
- "Sample .bashrc and .bash_profile Files". Linux Documentation Project.
- "Understanding Linux configuration files". IBM.com. Retrieved 2012-02-13.
- Pike, Rob. "A lesson in shortcuts.". Retrieved 2012-11-29.