Windows file systems
Microsoft Windows OS use two major file systems: FAT, inherited from old DOS with its later extension FAT32, and widely-used NTFS file systems. Recently released ReFS file system was developed by Microsoft as a new generation file system for Windows 8 Servers.
FAT (File Allocation Table):
FAT file system is one of the most simple types of file systems. It consists of file system descr iptor sector (boot sector or superblock), file system block allocation table (referenced as File Allocation Table) and plain storage space to store files and folders. Files on FAT are stored in directories. Each directory is an array of 32-byte records, each defines file or file extended attributes (e.g. long file name). File record references the first block of file. Any next block can be found through block allocation table by using it as linked-list.
Block allocation table contains an array of block descr iptors. Zero value indicates that the block is not used and non-zero â reference to the next block of the file or special value for fileend.
The number in FAT12, FAT16, FAT32 stands for the number if bits used to enumerate file system block. This means that FAT12 may use up to 4096 different block references, FAT16- 65536 and FAT32 - 4294967296. Actual maximum count of blocks is even less and depends on implementation of file system driver.
FAT12 was used for old floppy disks. FAT16 (or simply FAT) and FAT32 are widely used forflash memory cards and USB flash sticks. It is supported by mobile phones, digital cameras and other portable devices.
FAT or FAT32 is a file system, used on Windows-compatible external storages or disk partitions with size below 2GB (for FAT) or 32GB (for FAT32). Windows can not create FAT32 file system over 32GB (however Linux supports FAT32 up to 2TB).
NTFS (New Technology File System):
NTFS was introduced in Windows NT and at present is major file system for Windows. This is a default file system for disk partitions and the only file system that is supported for disk partitions over 32GB. The file system is quite extensible and supports many file properties, including access control, encryption etc. Each file on NTFS is stored as file descr iptor inMaster File Table and file content. Master file table contains all information about the file: size, allocation, name etc. The first and the last sectors of the file system contain file system settings (boot record or superblock). This file system uses 48 and 64 bit values to reference files, thus supporting quite large disk storages.
ReFS (Resilient File System):
ReFS is the latest development of Microsoft presently available for Windows 8 Servers. File system architecture absolutely differs from other Windows file systems and is mainly organized in form of B+-tree. ReFS has high tolerance to failures achieved due to new features included into the system. And, namely, Copy-on-Write (CoW): no metadata is modified without being copied; no data is written over the existing ones and rather into a new disk space. With any file modifications a new copy of metadata is created into any free storage space, and then the system creates a link from older metadata to the newer ones. As a result a system stores significant quantity of older backups in different places which provides for easy file recovery unless this storage space is overwritten.
All users including the superuser have their own home directories where all private data, like documents, bookmarks, or e-mail, are stored. System directories holding central configuration files or executable files can only be modified by the superuser.
In Linux, you can choose whether you want to manage files and folders with a file manager or if you rather like to use the command line which is the traditional way. The last-mentioned method is often faster but requires some deeper knowledge of several commands to list, create, delete, or edit files and their properties. A file manager provides a graphical and more intuitive way to handle these tasks.
In Linux, all files and directories are located in a tree-like structure. The topmost directory is referred to as the file system root or just / (not to be confused with the root user). The counterpart of / in a Windows system would probably be C:\. All other directories in Linux can be accessed from the root directory and are arranged in a hierarchical structure.
Find the key features of the Linux file system in the following list which also highlights some of the major differences between the Linux and the Windows/DOS file system:
Specifying Paths
As opposed to Windows, Linux does not use backslashes to separate the components of a pathname, it uses slashes instead. For example, the private data of users in Windows may be stored under C:\My Documents\Letters, whereas in Linux it would be stored under /home/username/Letters.
Partitions, Drives/Devices and Directories
Linux does not use drive letters as Windows does. From the mere appearance of a pathname in Linux you can not tell whether you are addressing a partition, a drive/device, a network device or an âordinaryâ directory.
Mounting and Unmounting
Another crucial difference between Windows/DOS and Linux is the concept of mounting and unmounting partitions, drives or directories. Windows detects partitions and drives during the boot process and assigns a drive letter to them. In Linux however, partitions or devices are usually not visible in the directory tree unless they are mounted, that means integrated into the file system at a specific location in the directory tree. As a normal user you cannot access data on a partition or a device unless it is mounted. But don't worryâ most of the times you do not have to mount partitions or devices manually. During the installation of your system, you can define partitions to be mounted automatically when the system is started. Removable devices are usually also detected and mounted automatically by your systemâthe desktop environments such as KDE or GNOME will inform you about the appearance of a new device.
Although this concept of mounting and unmounting may appear complicated or cumbersome at first sight this also offers great flexibility: for example you can easily mount a directory from a another machine over the network and act on that directory as though it were located on your local machine.
Case-Sensitivity
Linux distinguishes between uppercase and lowercase letters in the file system. For example, whether you name a file test.txt, TeST.txt or Test.txt make a difference in Linux. This also holds true for directories: You cannot access a directory named Letters by the name letters.
File Extensions
As opposed to Windows, files in Linux may have a file extension, such as .txt, but do not need to have one. When you start working with the shell this sometimes makes it difficult for beginners to differentiate between files and folders, depending on the command you use to list the contents of a directory.
Hidden Files
Similar to Windows, Linux also distinguishes between ânormalâ files and hidden files which are often configuration files that you usually do not want to access or see as a normal user. In Linux, hidden files are indicated by a dot in front (for example, .hiddenfile). In order to access hidden files you can switch view in the file managers.
File System Permissions
Because Linux is a multiuser system, every file in a Linux file system belongs to a user and a group. Only the owner of a file or directory (or, of course, root) can grant other users access permission to it. Linux basically distinguishes between three different types of access permissions: write permission, read permission and execute permission. You can only access a file or a folder if you have at least read permission to it. There are several ways to change the access permissions of files and folders: either traditionally via the shell or with the help of your desktop's file manager.
The following table provides a short overview of the most important higher-level directories you find on a Linux system. Find more detailed information about the directories and important subdirectories in the following list.
Microsoft Windows OS use two major file systems: FAT, inherited from old DOS with its later extension FAT32, and widely-used NTFS file systems. Recently released ReFS file system was developed by Microsoft as a new generation file system for Windows 8 Servers.
FAT (File Allocation Table):
FAT file system is one of the most simple types of file systems. It consists of file system descr iptor sector (boot sector or superblock), file system block allocation table (referenced as File Allocation Table) and plain storage space to store files and folders. Files on FAT are stored in directories. Each directory is an array of 32-byte records, each defines file or file extended attributes (e.g. long file name). File record references the first block of file. Any next block can be found through block allocation table by using it as linked-list.
Block allocation table contains an array of block descr iptors. Zero value indicates that the block is not used and non-zero â reference to the next block of the file or special value for fileend.
The number in FAT12, FAT16, FAT32 stands for the number if bits used to enumerate file system block. This means that FAT12 may use up to 4096 different block references, FAT16- 65536 and FAT32 - 4294967296. Actual maximum count of blocks is even less and depends on implementation of file system driver.
FAT12 was used for old floppy disks. FAT16 (or simply FAT) and FAT32 are widely used forflash memory cards and USB flash sticks. It is supported by mobile phones, digital cameras and other portable devices.
FAT or FAT32 is a file system, used on Windows-compatible external storages or disk partitions with size below 2GB (for FAT) or 32GB (for FAT32). Windows can not create FAT32 file system over 32GB (however Linux supports FAT32 up to 2TB).
NTFS (New Technology File System):
NTFS was introduced in Windows NT and at present is major file system for Windows. This is a default file system for disk partitions and the only file system that is supported for disk partitions over 32GB. The file system is quite extensible and supports many file properties, including access control, encryption etc. Each file on NTFS is stored as file descr iptor inMaster File Table and file content. Master file table contains all information about the file: size, allocation, name etc. The first and the last sectors of the file system contain file system settings (boot record or superblock). This file system uses 48 and 64 bit values to reference files, thus supporting quite large disk storages.
ReFS (Resilient File System):
ReFS is the latest development of Microsoft presently available for Windows 8 Servers. File system architecture absolutely differs from other Windows file systems and is mainly organized in form of B+-tree. ReFS has high tolerance to failures achieved due to new features included into the system. And, namely, Copy-on-Write (CoW): no metadata is modified without being copied; no data is written over the existing ones and rather into a new disk space. With any file modifications a new copy of metadata is created into any free storage space, and then the system creates a link from older metadata to the newer ones. As a result a system stores significant quantity of older backups in different places which provides for easy file recovery unless this storage space is overwritten.
The Linux File System
All users including the superuser have their own home directories where all private data, like documents, bookmarks, or e-mail, are stored. System directories holding central configuration files or executable files can only be modified by the superuser.
In Linux, you can choose whether you want to manage files and folders with a file manager or if you rather like to use the command line which is the traditional way. The last-mentioned method is often faster but requires some deeper knowledge of several commands to list, create, delete, or edit files and their properties. A file manager provides a graphical and more intuitive way to handle these tasks.
Key Features
In Linux, all files and directories are located in a tree-like structure. The topmost directory is referred to as the file system root or just / (not to be confused with the root user). The counterpart of / in a Windows system would probably be C:\. All other directories in Linux can be accessed from the root directory and are arranged in a hierarchical structure.
Find the key features of the Linux file system in the following list which also highlights some of the major differences between the Linux and the Windows/DOS file system:
Specifying Paths
As opposed to Windows, Linux does not use backslashes to separate the components of a pathname, it uses slashes instead. For example, the private data of users in Windows may be stored under C:\My Documents\Letters, whereas in Linux it would be stored under /home/username/Letters.
Partitions, Drives/Devices and Directories
Linux does not use drive letters as Windows does. From the mere appearance of a pathname in Linux you can not tell whether you are addressing a partition, a drive/device, a network device or an âordinaryâ directory.
Mounting and Unmounting
Another crucial difference between Windows/DOS and Linux is the concept of mounting and unmounting partitions, drives or directories. Windows detects partitions and drives during the boot process and assigns a drive letter to them. In Linux however, partitions or devices are usually not visible in the directory tree unless they are mounted, that means integrated into the file system at a specific location in the directory tree. As a normal user you cannot access data on a partition or a device unless it is mounted. But don't worryâ most of the times you do not have to mount partitions or devices manually. During the installation of your system, you can define partitions to be mounted automatically when the system is started. Removable devices are usually also detected and mounted automatically by your systemâthe desktop environments such as KDE or GNOME will inform you about the appearance of a new device.
Although this concept of mounting and unmounting may appear complicated or cumbersome at first sight this also offers great flexibility: for example you can easily mount a directory from a another machine over the network and act on that directory as though it were located on your local machine.
Case-Sensitivity
Linux distinguishes between uppercase and lowercase letters in the file system. For example, whether you name a file test.txt, TeST.txt or Test.txt make a difference in Linux. This also holds true for directories: You cannot access a directory named Letters by the name letters.
File Extensions
As opposed to Windows, files in Linux may have a file extension, such as .txt, but do not need to have one. When you start working with the shell this sometimes makes it difficult for beginners to differentiate between files and folders, depending on the command you use to list the contents of a directory.
Hidden Files
Similar to Windows, Linux also distinguishes between ânormalâ files and hidden files which are often configuration files that you usually do not want to access or see as a normal user. In Linux, hidden files are indicated by a dot in front (for example, .hiddenfile). In order to access hidden files you can switch view in the file managers.
File System Permissions
Because Linux is a multiuser system, every file in a Linux file system belongs to a user and a group. Only the owner of a file or directory (or, of course, root) can grant other users access permission to it. Linux basically distinguishes between three different types of access permissions: write permission, read permission and execute permission. You can only access a file or a folder if you have at least read permission to it. There are several ways to change the access permissions of files and folders: either traditionally via the shell or with the help of your desktop's file manager.
The Directory Structure
The following table provides a short overview of the most important higher-level directories you find on a Linux system. Find more detailed information about the directories and important subdirectories in the following list.
