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Articles by Satish Kumar
Page 71 of 94
What Does a Double-Dash in Shell Commands Mean
Introduction If you are familiar with command line interface, you have probably encountered a double-dash (--) in some of commands you use. This article seeks to explain what double-dash means and how it affects behavior of shell commands. What is a Double-Dash in Shell Commands? A double-dash is a syntax used in shell commands to signify end of command options and beginning of positional arguments. In other words, it separates command options from arguments that command operates on. Many shell commands allow you to specify options or flags that modify behavior of command. For example, ls command allows you to ...
Read MoreAppend Lines to a File in Linux
Introduction In Linux, files are often used to store data that is either created by a program or generated by user. It is common for users to append new lines of data to existing files rather than creating new ones from scratch. This article will explain how to append lines to a file in Linux, including several subheadings and examples. Using echo command The easiest way to append new lines to a file is by using echo command. echo command allows you to display a message on screen, but it can also redirect message to a file. Here's how to ...
Read MoreRecursively List All Files in a Directory Including Symlinks
Introduction When it comes to managing files and directories in any operating system, being able to list all files in a directory is an essential task. However, it becomes a bit more complicated when you need to recursively list all files in a directory, including symlinks. This is particularly important for developers and system administrators who work with large, complex file systems. In this article, we will cover how to recursively list all files in a directory, including symlinks, with examples and subheadings. What is a symlink? A symlink, also known as a symbolic link or soft link, is a ...
Read MoreRepeat a Linux Command at a Given Interval
Linux is a powerful operating system that offers a wide range of command-line tools for executing various tasks. One of tasks that often need to be performed is repeating a command at a given interval. This feature can be useful for several reasons, such as monitoring system performance, running scheduled tasks, and performing backups. In this article, we will explore how to repeat a Linux command at a given interval. We will discuss various ways to achieve this, including using cron utility, watch command, and sleep command. Using Cron to Repeat a Command The cron utility is a time-based job ...
Read MoreSave Modifications In-Place with AWK
Introduction The awk command is a versatile tool used in Unix and Linux environments for text processing and manipulation. One of its key features is ability to modify files in-place, which is particularly useful when working with large datasets. In this article, we will explore how to save modifications in-place with awk, including examples and subheadings to aid understanding. Understanding Awk Before we delve into how to save modifications in-place with awk, it's important to understand what awk is and how it works. Awk is a programming language designed for processing text files, with primary focus on processing rows of ...
Read MoreCMake configure fails to find Qt5 on Linux
Introduction CMake is an open-source cross-platform tool used for building, testing and packaging software. It is widely used in industry for its portability and ability to generate build scripts for various build systems such as make, ninja, etc. Qt is a cross-platform application development framework that is widely used in creating GUI applications. In this article, we will discuss a common issue that developers face while configuring a CMake project on Linux, i.e. "CMake configure fails to find Qt5". Understanding Issue When we configure a CMake project with Qt5, CMake needs to find Qt5 package, which includes required libraries, header ...
Read MoreHow to investigate which process causes wakeups during laptop sleep-mode in MacOS (or Linux)
When a laptop goes into sleep mode, operating system tries to conserve power by stopping most processes and putting computer in a low-power state. However, sometimes a process may continue to run or periodically wake up computer, preventing it from entering a deep sleep state. This can lead to increased power consumption and a shorter battery life. In this article, we'll explore how to investigate which process is causing wakeups during laptop sleep-mode in MacOS or Linux. Understanding Power Management Subsystem Before we dive into how to investigate sleep mode wakeups, it's important to understand power management subsystem in your ...
Read MoreELF executable file many zero bytes
Introduction In world of computer programming, an ELF (Executable and Linkable Format) file is a binary file format used in Unix-based operating systems such as Linux, FreeBSD, and Solaris. These files contain executable code and data, which are used to launch programs and libraries. In some cases, however, ELF files may contain many zero bytes. In this article, we will explore why ELF files may contain many zero bytes, their impact on programs, and how to fix this issue. Why ELF files contain many zero bytes? An ELF file consists of a header followed by sections containing executable code, data, ...
Read MorePDF generation from XHTML in a LAMP environment
The LAMP environment is widely used for web development, and it is an acronym for Linux, Apache, MySQL, and PHP. This environment is an open-source platform that is easy to use and deploy. PDF format is commonly used for sharing and exchanging documents over internet. However, generating PDF documents can be a challenging task in a LAMP environment, especially when converting XHTML documents. In this article, we will explore different methods used for PDF generation from XHTML in a LAMP environment. What is XHTML? XHTML stands for Extensible Hypertext Markup Language, which is a markup language that is used to ...
Read MorePHP and Xvfb usage
Introduction Xvfb stands for "X Virtual Frame Buffer" which is used to create a virtual display in memory without any attached physical display device. It allows running graphical applications without any actual graphics hardware. PHP is a server-side scripting language widely used for web development. In this article, we will discuss how we can use Xvfb with PHP to run graphical applications in headless mode. Why do we need Xvfb with PHP? PHP is a server-side scripting language and doesn't provide any direct support for graphics and user interfaces. Most of PHP-based web applications are built on top of popular ...
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