JNTU B.Tech III SCRIPTING LANGUAGES Previous Question Paper (September - 2021 - R16)

Linux provides a set of system calls to manage files, which are the fundamental building blocks of the file system. Key functions include:

• open(): Used to create or open a file. It returns a file descriptor. Example: int fd = open("file.txt", O_RDWR | O_CREAT);
• read(): Reads data from a file descriptor into a buffer. Example: read(fd, buffer, size);
• write(): Writes data from a buffer to a file descriptor. Example: write(fd, "Hello", 5);
• close(): Terminates the association between the file descriptor and the file. Example: close(fd);
• lseek(): Repositions the read/write file offset. Example: lseek(fd, 0, SEEK_SET);
• stat(): Retrieves file metadata such as size, permissions, and ownership. Example: stat("file.txt", &file_info);

The Linux kernel is the core interface between hardware and processes. Its primary features include modularity, multitasking, and support for symmetric multiprocessing (SMP). The key components are:

• System Call Interface (SCI): Acts as the bridge between user-space applications and kernel services.
• Process Management: Handles the creation, scheduling, and termination of processes using the scheduler.
• Memory Management: Manages virtual memory, paging, and physical RAM allocation to ensure process isolation.
• Virtual File System (VFS): Provides an abstraction layer that allows the kernel to support multiple file system formats transparently.
• Network Stack: Implements protocols like TCP/IP to manage network communication.
• Device Drivers: Modules that allow the kernel to communicate with specific hardware components like disks, keyboards, and network cards.