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An operating system is a construct that allows user application programs to interact with the system hardware. Operating system by itself does not provide any function but it provides an atmosphere in which different applications and programs can do useful work. The operating system can be observed from two distinct perspectives − the user view and the system view. Each perspective focuses on different aspects and priorities of the operating system's functionality. Operating System Perspectives User View Focus: Ease of Use ... Read More
In this article, we will discuss the concept of stale file handles in Linux and how to understand and resolve them. We'll explore the relationship between file handles, inodes, and the filesystem to understand why stale file handles occur and how to fix them. The examples in this tutorial have been tested on Debian 10.10 (Buster) with GNU Bash 5.0.3. The concepts are POSIX-compliant and apply to most Unix-like systems. What are File Handles? A file handle (or file descriptor) is an integer value that represents a reference to an open file. The operating system maintains a ... Read More
In the world of Linux system administration, performance monitoring is a critical task for maintaining optimal system health. The Sysstat utilities are among the most powerful and widely-used tools for this purpose. This comprehensive collection provides detailed insights into CPU utilization, memory usage, disk activity, network statistics, and much more. In this article, we will explore 20 essential commands from the Sysstat utilities suite that every Linux administrator should master for effective performance monitoring. Installation of Sysstat Utilities Before exploring the commands, you'll need to install the Sysstat package. While most modern Linux distributions include it by ... Read More
File access methods define how data is accessed and modified within a file. There are different file access methods, each with its own set of strengths and limitations. The four primary file access methods are sequential access, random access, direct access, and indexed access. Understanding the differences between each method is important for effective data management and choosing the right approach for specific applications. What is File Access Method A file access method is a way of accessing and manipulating data stored in a file. It determines how data is read from and written to computer storage devices. ... Read More
HTTP/2 is the latest version of the HTTP protocol, designed to improve website performance and security. Nginx is a popular web server that supports HTTP/2. If you're using Nginx and want to enable HTTP/2 for your website, this article will guide you through the process. Prerequisites Before enabling HTTP/2, ensure your system meets these requirements: Nginx version 1.9.5 or later OpenSSL 1.0.2 or later for ALPN support Valid SSL/TLS certificate Step 1: Check Nginx Version First, verify your Nginx version supports HTTP/2: nginx -v If your version is older ... Read More
System security requires careful management of root access, especially in multi-user environments. The su command allows users to switch accounts and potentially gain root privileges, which can pose security risks when combined with sudo access. This guide explains how to disable su access for sudo users to enhance system security. Understanding Sudo and Su Commands The sudo command allows authorized users to execute administrative tasks with elevated privileges by entering their own password rather than the root password. It provides controlled, temporary access to root-level functions while maintaining an audit trail of executed commands. The su command ... Read More
To change the shell working directory, we use the cd command in the Linux system. The cd (change directory) command is one of the most fundamental navigation commands that allows users to move between different directories in the filesystem. cd (change directory) The cd command is used to change the current working directory in Linux/Unix operating systems. It is equivalent to the cd or chdir command in Windows. The command is also available in the EFI shell (Extensible Firmware Shell). By default, when you open a new terminal session, the current working directory is set to your home ... Read More
Semaphores are integer variables used to solve the critical section problem through two atomic operations: wait and signal. They provide a synchronization mechanism that allows processes to coordinate access to shared resources safely. How Semaphores Work Semaphores use two fundamental operations that must be executed atomically (without interruption): Wait Operation The wait operation decrements the value of its argument S if it is positive. If S is zero or negative, the process blocks until the semaphore becomes positive. wait(S) { while (S
To determine whether our file system uses SSD or HDD technology, we need to identify which type of storage device is used by our Linux system. Understanding storage hardware helps optimize performance and make informed decisions about data placement. There are many different aspects of Linux storage with numerous tools available for reading and configuring storage devices. We use terms like "drive", "volume", and "mount point" to describe hard drives, optical discs, and USB sticks. To understand the underlying technology, we focus on two key aspects − What physical disk or block device we are examining (using ... Read More
As a Linux administrator, one of the most important aspects of maintaining a secure and stable network is implementing an effective firewall. IPtables is a powerful firewall tool that comes pre-installed on most Linux distributions. In this article, we will explore 20 useful IPtables firewall rules that every Linux administrator should know. These rules will help you secure your network and prevent unauthorized access, while also allowing legitimate traffic to pass through. Block All Incoming Traffic Except SSH The first rule is to block all incoming traffic except for SSH. SSH is a secure way to access your ... Read More