Linux File Hierarchy

1. Linux File Hierarchy Manoj CSE Yr 3

2. Introduction • What is Hierarchy? • Classification of things based on relative importance • File Hierarchy • A Tree Structure • Directories have sub elements or subordinates

3. File Organization • Linux organizes its files differently from Windows. • "On a UNIX system, everything is a file; if something is not a file, it is a process."

4. Partitions • Linux uses multiple partitions on the same disk • These are called mounts • Places where the disks – mount points

5. Types Partitions • There are two kinds of major partitions on a Linux system: • data partition: normal Linux system data, including the root partition containing all the data to start up and run the system; and • swap partition: expansion of the computer's physical memory, extra memory on hard disk.

6. The Linux System User commands includes executable programs and scripts The shell interprets user commands. It is responsible for finding the commands and starting their execution. Several different shells are available. Bash is popular, The kernel manages the hardware resources for the rest of the system.

7. root Directories / etc home usr passwd inittab User home directories neale scully marty a b Data files • Linux files are stored in a single rooted, hierarchical file system • Data files are stored in directories (folders) • Directories may be nested as deep as needed

8. File Organization

9. The Root Directory • /bin • /boot • /dev • /etc • /home • /initrd • /lib • /lost+found • /media • /mnt • /opt • /proc • /root • /sbin • /usr • /srv • /tmp • /var

10. 1. /bin • Contains several useful commands that are of use to both the system administrator as well as non-privileged users. • Usually contains the shells like bash, csh, etc.... and commonly used commands like cp, mv, rm, cat, ls. • Also contains programs which boot scripts may depend on • There are no (real) subdirectories in /bin

11. 2. /boot • Contains everything required for the boot process except for configuration files not needed at boot time and the map installer • Stores data that is used before the kernel begins executing user-mode programs • May include the system kernel (under symbolically linked)

12. 3. /dev • Usualy is the location of device files • A device and a file both can be read from and written to. So config a device is same with edit a file. EX: sending data to /dev/ttyS0 that means you are sending data to a communication device, such as a modem. • 'block devices' are devices that store or hold data • 'character devices' can be thought of as devices that transmit or transfer data

13. 4. /etc • Contains all system related configuration files • Local file used to control the operation of a program • Those files must be static and cannot be an executable binary

14. 5. /home • The user home directories • Accessible only to its owner and the system administrator • Contains the user’s personal configuration files • Quite large to be used as User’s Documents Space

15. 6. /initrd • Provides the capability to load a RAM disk by the boot loader. This RAM disk can then be mounted as the root file system and programs can be run from it. Afterwards, a new root file system can be mounted from a different device. The previous root (from initrd) is then moved to a directory and can be subsequently unmounted. • Initrd is mainly designed to allow system startup to occur in two phases, where the kernel comes up with a minimum set of compiled-in drivers, and where additional modules are loaded from initrd.

16. 7. /lib • Contains kernel modules and those shared library images (the C programming code library) needed to boot the system and run the commands in the root filesystem, ie. by binaries in /bin and /sbin • Windows equivalent to a shared library would be a DLL (dynamically linked library) file

17. 8. /lost+found • Contains the files which were recovered after an unexpected event, such as a proper shutdown. • Try to move each file back to its original location

18. 9. /media • Contains subdirectories which are used as mount points for removeable media such as floppy disks, cdroms and zip disks

19. 10. /mnt • This is a generic mount point under mounted (mount is to make a filesystem available to the system) the filesystems or devices. • When a filesystem no longer needs to be mounted, it can be unmounted with umount • mount /dev/hda2 /home • umount /dev/hda2

20. 11. /opt • This directory is reserved for all the software and add-on packages that are not part of the default installation • /opt/'package'  C:\Windows\Progam Files\"Program Name"

21. 12. /proc • Virtual filesystem, runtime system information (e.g. system memory, devices mounted, hardware configuration, etc). • The most of them have a file size of 0 • To view, use “cat”. Use “vi” to edit.

22. 13. /root • The home directory of the System Administrator, 'root' • Why not in '/home'? Because '/home' is often located on a different partition or even on another system and would thus be inaccessible to 'root' when - for some reason - only '/' is mounted.

23. 14. /sbin • Like /bin bet less important • /sbin should contain only binaries essential for booting, restoring, recovering, and/or repairing the system in addition to the binaries in /bin.

24. 14. /sbin … detail • shutdown • Fastboot • Fasthalt • fdisk • fsck • fsck.* • getty • halt • ifconfig • Command to bring the system down. • Reboot the system without checking the disks (optional) • Stop the system without checking the disks (optional) • Partition table manipulator (optional) • File system check and repair utility (optional) • File system check and repair utility for a specific filesystem (optional) • The getty program (optional) • Command to stop the system (optional) • Configure a network interface (optional)

25. 15. /usr • The largest share of data on a system • the most important directories in the system as it contains all the user binaries, their documentation, libraries, header files, etc.... X and its supporting libraries, and User programs like telnet, ftp, etc.... as well, can be found here.

26. 16. /var • Contains variable data, files and directories the system must be able to write to during operation, like system logging files, mail and printer spool directories, and transient and temporary files

27. Current Directory • One directory is designated the current working directory • if you omit the leading / then path name is relative to the current working directory • Use pwd to find out where you are

28. Some Special Filenames • Some file names are special: • / The root directory (not to be confused with the root user) • . The current directory • .. The parent (previous) directory • ~ My home directory • Examples: • ./a same as a • ../jane/x go up one level then look in directory • jane for x

29. That’s all Folks!