Good Morning. Session -5. Recap…. Understanding Distributions Major Distribution. Session Objectives. Understanding File System File System Used Windows (FAT, FAT32,NTFS) Linux (ext2,ext3) File / Directory Structure of Red Hat LINUX Linux FHS vs Windows File System. File System.
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File systems organize the data stored on computer hard drives, keeping track of the physical locations of all data elements on disk while allowing users to quickly and reliably retrieve files when needed
The file system acts as a digital index that lets a computer instantly find a specific file, regardless of the size or configuration of the storage drive or where the data bytes associated with the file sit on the drive's storage platters.
The file system is based on management of clusters, the smallest disk unit that the operating system is able to manage.
A cluster consists of one or more sectors, so the larger the cluster size, the fewer entities the operating system will have to manage.
*4GB under Windows NT
An operating system's file system structure is its most basic level of organization. Almost all of the ways an operating system interacts with its users, applications, and security model are dependent upon the way it stores its files on a storage device. It is crucial for a variety of reasons that users, as well as programs, be able to refer to a common guideline to know where to read and write files.
The major advantages of using the FHS are the predictability and consistency of file locations. Instead of an administrator searching the entire filesystem for a particular type of file, he can know that it will be in one of a few established locations.
FHS provides sepcific requirements on placement of files in the directory structure. The placement of files are based upon the type of information they contain.
For more information on the FHS, refer to http://www.pathname.com/fhs/.
Shareable vs. unshareable files — Shareable files are those that can be accessed by various hosts; unshareable files are not available to any other hosts.
Variable vs. static files — Variable files can change at any time without any intervention; static files, such as read-only documentation and binaries, do not change without an action from the system administrator or an agent that the system administrator has placed in motion to accomplish that task
The / (Root) Directory
The root partition/volume is identified by a forward slash (/). All other directories are attached (mounted) to this parent directory. It is equivalent to the system drive (C:\ ) in Windows.
The /bin Directory
This directory contains all the commands that will be used by the user i.e. common Linux user commands. It can’t contain any subdirectory
The /dev Directory
The /dev directory contains file system entries that represent devices that are attached to the system. These files are essential for the system to function properly
The /mnt directory is for temporarily mounted file systems, such as CD-ROMs , floppy disks or usb drives.
The /lib Directory
The /lib directory should contain only those libraries that are needed to execute the binaries in /bin and /sbin. These shared library images are particularly important for booting the system and executing commands within the root file system
The /etc Directory
The /etc directory is reserved for configuration files that are local to your machine. No binaries are to be put in /etc. Any binaries that were formerly put in /etc should now go into /sbin or possibly /bin.
The X11 and skel directories are subdirectories of the /etc directory. The X11 directory is for X11 configuration files such as XF86Config. The skel directory is for "skeleton" user files, which are used to populate a home directory when a user is first created.
The /usr directory is for files that can be shared across a whole site. The /usr directory usually has its own partition, and it should be mountable read-only.
The /root Directory
This is the home directory of the user “root”.
The /home Directory
It contains the directory of users on the system. The subdirectory will be named for the user to whom it belong.
The /boot Directory
It contains the kernel of the system and also contains all the programmes required for booting like Boot Loader.
It contains variable information such as system log and print queues.
The /proc Directory
Within the /proc/ directory, one can find a wealth of information about the system hardware and any processes currently running. In addition, some of the files within the /proc/ directory tree can be manipulated by users and applications to communicate configuration changes to the kernel.
In MS-DOS and Windows file systems, drive letters represent different storage devices (forexample, A: is a floppy drive and C: is a hard disk). In Linux, all storage devices are fit into the file system hierarchy. So, the fact that all of /usr may be on a separate hard disk or that /mnt/rem1 is a file system from another computer is invisible to the user.
Slashes, rather than backslashes, are used to separate directory names in Linux. So,C:\home\chris in an MS system is /home/chris in a Linux system.
Filenames almost always have suffixes in DOS (such as .txt for text files or .doc for word processingfiles). Although at times you can use that convention in Linux, three-character suffixes have no required meaning in Linux. They can be useful for identifying a file type.
Many Linux applications and desktop environments use file suffixes to determine the contents of a file. In Linux, however, DOS command extensions such as .com, .exe, and .bat don’t necessarily signify an executable (permission flags make Linux files executable).
Every file and directory in a Linux system has permissions and ownership associated with it. Security varies among Microsoft systems. Because DOS and MS Windows began as single-user systems, file ownership was not built into those systems when they were designed. Later releases added features such as file and folder attributes to address this problem.