{"id":79,"date":"2018-07-13T04:23:53","date_gmt":"2018-07-13T04:23:53","guid":{"rendered":"http:\/\/itp7.epgpbooks.inflibnet.ac.in\/?post_type=chapter&p=79"},"modified":"2019-05-16T07:03:18","modified_gmt":"2019-05-16T07:03:18","slug":"overview-of-gnu-linux-filesystem","status":"publish","type":"chapter","link":"https:\/\/ebooks.inflibnet.ac.in\/itp7\/chapter\/overview-of-gnu-linux-filesystem\/","title":{"rendered":"Overview of GNU\/Linux filesystem"},"content":{"raw":"
\"epgp<\/a>\r\n<\/span><\/div>\r\n \r\n\r\nIntroduction<\/strong>\r\n\r\n \r\n

Usually, a file is an object that stores data, information, settings or commands in a computer system. A directory is a structure that is used to store collection of files. A filesystem is the methods and data structures that an operating system uses to keep track of files on a disk or partition; that is, the way the files are organized on the disk.<\/p>\r\n \r\n

In Linux, the files are organized in a tree structure. A directory may contain directories and files. Operations like creation, modification, deletion can be performed on a file. Files can be readable, writable and executable. For instance, if a user types his bio-data in a file, we say that the file is readable. A file can be executable, certain commands and programs are stored as executable files. Certain files in Linux are read-only files, such files are managed by the system and prevents the user from making accidental changes.<\/p>\r\n \r\n

The partitions in hard disk are viewed different by Windows OS and Linux OS. As shown in figure 1, the windows OS sees partitions as C:, D:, etc. while the Linux OS view them as \u201c\/\u201d (root) partition and its sub-directories like \u201c\/bin\u201d, \u201c\/boot\u201d etc. Within each directory, there can be sub-directories. The directories and sub-directories may contain file(s). A file system is a data structure that stores index of each and every file. As we know, files reside in physical form of data blocks in the hard disk. The filesystem is responsible to map the physical location to its logical location in directory structure. The way Linux and Windows maintain files are entirely different, so they have distinct filesystems.<\/p>\r\n

\"\"<\/p>\r\n

Figure 1: Partitions of Hard Disk<\/strong><\/p>\r\n \r\n\r\nLinux Directory Structure<\/strong>\r\n\r\n \r\n

Linux organizes the files in tree structure. As you can see in the figure 2, the \u201c\/\u201d directory is at the top level and other directories branch out from the root. Files are within these directories. This gives us a hierarchical structure. The root directory is not the same as the root user.<\/p>\r\n \r\n

The hierarchical filesystem also contains other elements in the path (known as directory names), which are separated by forward slashes (\/), as in \/var\/log\/messages<\/strong>, where the last element is the actual file name (messages).<\/p>\r\n

\"\"<\/p>\r\n\r\n

\r\n\r\nLinux classifies the files into 3 main categories and accordingly they are placed in different directories. The classification is as follows:\r\n