Jawaharlal Nehru Technological University Hyderabad MCA 2017 LINUX PROGRAMMING Previous Question Paper (August - 2017 - R09)

Linux is a multitasking and multi-user operating system known for its stability and security. Key features include:

• Open Source: The source code is freely available, allowing users to modify and redistribute it.
• Portability: It can run on various hardware platforms with minimal changes.
• Hierarchical File System: Linux organizes files in a tree-like structure starting from the root directory.
• Shell: A powerful command-line interpreter that provides an interface between the user and the kernel.
• Security: It offers robust authentication, authorization, and file permission mechanisms.
• Virtual Memory: Efficient memory management that allows running processes larger than physical RAM.

A Linux directory is a special file that contains a list of filenames and their corresponding inode numbers. The inode contains metadata about the file, such as permissions, ownership, and data block locations, but not the filename itself.

The mechanisms for updating directory entries are as follows:

• cp (Copy): When copying a file, the system creates a new inode for the destination file, copies the data blocks, and adds a new entry (filename and new inode number) to the destination directory.
• mv (Move/Rename): If moving within the same filesystem, the system simply updates the directory entry by changing the filename associated with the existing inode. The inode number remains unchanged.
• rm (Remove): The system removes the entry (filename and inode number) from the directory file. If the link count of the inode drops to zero, the system deallocates the inode and the associated data blocks.