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 any file or directory that starts with a period or full stop character (for example, /home/user/.config) is to be treated as hidden – that is, the
ls command does not display them unless the
-a flag (
ls -a) is used.
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
.. directory entries were added to the filesystem, it was decided that the
ls command should not display them. However, the program was mistakenly written to exclude any file whose name started with a
. character, rather than the exact names
In the GNOME desktop environment (as well as all programs written using GLib), filenames listed in a file named .hidden in each directory are also excluded from display. In GNOME's file manager, the keyboard shortcut ^ Ctrl+H enables the display of both kinds of hidden files.
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.
Under Windows Explorer, content of a directory can be hidden just by appending a pre-defined CLSID  to the end of the folder name. The directory is still visible, but its content becomes one of the Windows Special Folders. However, the real content of this directory can still be seen using CLI command
Malicious programs can use this functionality to hide their presence.
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- Canonical Names of Control Panel Items
- The Secret BEHIND the Windows 7 “GodMode”