Hidden file and hidden directory

In computing, a hidden folder (sometimes hidden directory) or hidden file is a folder or which utilities do not display by default when showing a directory listing. They are commonly used for storing user preferences or preserving the state of a utility and are frequently created implicitly by using various utilities. They are not a security mechanism because access is not restricted – usually the intent is simply to not "clutter" the display of the contents of a directory listing with files the user did not directly create. In Unix-like operating systems, any file or folder that starts with a dot character (for example, ), commonly called a dot file or dotfile, is to be treated as hidden – that is, the ls command does not display them unless the -a or -A flags (ls -a or ls -A) are used. In most command-line shells, will not match files whose names start with . unless the wildcard itself starts with an explicit . . A convention arose of using dotfiles in the user's home directory to store per-user configuration or informational text. Early uses of this were the well-known dotfiles , .login, and .cshrc, which are configuration files for the Bourne shell and C shell and shells compatible with them, and .plan and .project, both used by the finger and name commands. Many applications, from bash to desktop environments such as GNOME, now store their per-user configuration this way, but the Unix/Linux freedesktop.org XDG Base Directory Specification aims to migrate user config files from individual dotfiles in $HOME to non-hidden files in the hidden directory$HOME/.config. The Android operating system uses empty .nomedia files to tell smartphone apps not to display or include the contents of the folder. This prevents digital photos and digital music files from being shown in picture galleries or played in MP3 player apps. This is useful to prevent downloaded voicemail files from playing between the songs in a playlist, and to keep personal photos private while still allowing those in other folders to be shared in person with friends, family, and colleagues.