About Linux File System Hierarchy | Infosecwithme Blog

About Linux File System Hierarchy | BlackHatTrick Blog

Hell all,

In corporate environment almost 70% servers are Linux Based OS so there is demand for company to get the employee which is very well aware of Linux OS.

Here is first Basic Article for Newbie to know how Linux OS is divided and wat is file structure.

kindly refer below snap to get it clear.

Linux file system description

In order to manage all those files in an orderly fashion, man likes to think of them in an ordered tree-like structure on the hard disk, as we know from MS-DOS (Disk Operating System) for instance. The large branches contain more branches, and the branches at the end contain the tree’s leaves or normal files. For now we will use this image of the tree, but we will find out later why this is not a fully accurate image.

DIRECTORY	DESCRIPTION
/	Primary hierarchy root and root directory of the entire file system hierarchy.
/bin	Essential command binaries that need to be available in single user mode; for all users, e.g., cat, ls, cp.
/boot	Boot loader files, e.g., kernels, initrd.
/dev	Essential devices, e.g., /dev/null.
/etc	Host-specific system-wide configuration filesThere has been controversy over the meaning of the name itself. In early versions of the UNIX Implementation Document from Bell labs, /etc is referred to as theetcetera directory, as this directory historically held everything that did not belong elsewhere (however, the FHS restricts /etc to static configuration files and may not contain binaries). Since the publication of early documentation, the directory name has been re-designated in various ways. Recent interpretations include backronyms such as “Editable Text Configuration” or “Extended Tool Chest”.
/opt	Configuration files for add-on packages that are stored in /opt/.
/sgml	Configuration files, such as catalogs, for software that processes SGML.
/X11	Configuration files for the X Window System, version 11.
/xml	Configuration files, such as catalogs, for software that processes XML.
/home	Users’ home directories, containing saved files, personal settings, etc.
/lib	Libraries essential for the binaries in /bin/ and /sbin/.
/lib	Alternate format essential libraries. Such directories are optional, but if they exist, they have some requirements.
/media	Mount points for removable media such as CD-ROMs (appeared in FHS-2.3).
/mnt	Temporarily mounted filesystems.
/opt	Optional application software packages.
/proc	Virtual filesystem providing process and kernel information as files. In Linux, corresponds to a procfs mount.
/root	Home directory for the root user.
/sbin	Essential system binaries, e.g., init, ip, mount.
/srv	Site-specific data which are served by the system.
/tmp	Temporary files (see also /var/tmp). Often not preserved between system reboots.
/usr	Secondary hierarchy for read-only user data; contains the majority of (multi-)user utilities and applications.
/bin	Non-essential command binaries (not needed in single user mode); for all users.
/include	Standard include files.
/lib	Libraries for the binaries in /usr/bin/ and /usr/sbin/.
/lib	Alternate format libraries (optional).
/local	Tertiary hierarchy for local data, specific to this host. Typically has further subdirectories, e.g., bin/,lib/, share/.
/sbin	Non-essential system binaries, e.g., daemons for various network-services.
/share	Architecture-independent (shared) data.
/src	Source code, e.g., the kernel source code with its header files.
/X11R6	X Window System, Version 11, Release 6.
/var	Variable files—files whose content is expected to continually change during normal operation of the system—such as logs, spool files, and temporary e-mail files.
/cache	Application cache data. Such data are locally generated as a result of time-consuming I/O or calculation. The application must be able to regenerate or restore the data. The cached files can be deleted without loss of data.
/lib	State information. Persistent data modified by programs as they run, e.g., databases, packaging system metadata, etc.
/lock	Lock files. Files keeping track of resources currently in use.
/log	Log files. Various logs.
/mail	Users’ mailboxes.
/opt	Variable data from add-on packages that are stored in /opt/.
/run	Information about the running system since last boot, e.g., currently logged-in users and running daemons.
/spool	Spool for tasks waiting to be processed, e.g., print queues and outgoing mail queue.
/mail	Deprecated location for users’ mailboxes.
/tmp	Temporary files to be preserved between reboots.

Types of files in Linux

Most files are just files, called regular files; they contain normal data, for example text files, executable files or programs, input for or output from a program and so on.

While it is reasonably safe to suppose that everything you encounter on a Linux system is a file, there are some exceptions.

• Directories: files that are lists of other files.
• Special files: the mechanism used for input and output. Most special files are in /dev, we will discuss them later.
• Links: a system to make a file or directory visible in multiple parts of the system’s file tree. We will talk about links in detail.
• (Domain) sockets: a special file type, similar to TCP/IP sockets, providing inter-process networking protected by the file system’s access control.
• Named pipes: act more or less like sockets and form a way for processes to communicate with each other, without using network socket semantics.

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