Overview ImageMagick is an open source software suite for image manipulation. We can install it on our system using apt−get and then run commands through its command line interface (CLI). We’ll take a quick peek at some of the most popular methods for manipulating images with ImageMagick. Installation Let’s start by downloading ImageMagick, which we can install using our package manager (e.g., apt). We can also download the binary directly or compile it from the sources. After installing the software, let’s check whether we've successfully installed it by looking at its current status. $ magick -version Version: ImageMagick 7.0.8-13 Q16 ... Read More

Overview You may sometimes want to run several commands sequentially in Linux. To accomplish this, you can use command chaining. For example, if you wanted to download a compressed archive, decompress it, and then remove the resulting archive from disk, you could type these three commands together. Here, we’ll look at some methods for serializing commands using Bash in Linux. Even if they're already running. Inline Command Chaining Bash has great flexibility and powerful features for the end−users. We can create long sequences of instructions to perform any number of tasks. ... Chained operations ... Read More

Overview When working with Bash scripts or Unix/Linux command line tools, we often write the same command lines over and over again. Often, these command lines are long and must be repeated multiple times. For instance, when logging into a remote server daily, copying a local folder to the remote server, or searching for hidden files or directories within a directory. You can create aliases using the alias command. In this guide, I will show you how to create an alias that accepts parameters on Linux. This is useful if you want to run a single command repeatedly without having ... Read More

Overview In this tutorial, we will learn how to find all links for a specific file on Linux. We will use the command lsof to list all files that are opened by any process and then grep to filter out only those files that have a link to our target file. What is a Link? A link in Unix/Linux systems is an association between two different files or directories. When you create a link, it creates a new name for the original file or directory. You can access the linked file through its alias instead of accessing the original file ... Read More

Overview We'll learn how to use Linux commands to get the number of occurrences of a specific character in an input file. We're assuming that you know some common Linux commands, including grep, awk, and tr. We'll also suppose that our input file tpoint.txt contains some dummy data − $ cat tpoint.txt "I Love Tpoint!!!" "Tpoint is great!!!" For the rest of the tutorial, we’ll be using tpoint.txt for demonstration purposes. Using the grep Command The grep command looks for a specific string in an input file. We’ll now look at the command to get the number of characters ... Read More

Overview Finding software’s installation directory is a very common operation. One common reason is for updating the PATH environment variable. For example, Java developers are often interested in finding the installation directory of Java. This article shows how to find the location of the JDK on Linux. The method described here works on both 32-bit and 64-bit versions of these operating systems. The JDK includes many tools that can be used by programmers. In this article we will look at some of them. We will start with the most basic tool: the java command. The Java Command The java command ... Read More

Overview To determine whether our file system uses SSD or HDD technology, we need to know which type of storage device is used by our operating system. There are many different aspects of Linux storage. There seem to be just as many tools available for reading and configuring our storage. We use words like “drive’, ‘volume’, and ‘mount point’ when we want to describe hard drives, optical discs, and USB sticks. But to understand the underlying technology, we only really care about two things − What physical disk or block device we are looking at (from df) The hardware ... Read More

Overview In this article, we will discuss about the concept of stale file handles and how to avoid it in your application. We will also see some examples on how to use fcntl() function to check if a file handle is valid or not. The code in this tutorial has been tested on Debian 10.10 (Buster) with GNU Bash 5.0.3. It is POSIX−compliant and should work in any such environment. What are Stale File Handles? A file handle can be considered as an integer value that represents the access rights for a particular file. The file system maintains a list ... Read More

Overview This article explains how to delete an environment variable from the system. An environment variable is a special kind of variable that can be used by all processes running on your machine. The name of this variable is EXPORTED_VARIABLE. You can use it to pass information between different programs or even between different users. For example, you might want to export the path to the directory where you store your music files so that other users can access them easily. Environment Variable The environment variables are stored as part of the process’s memory space and they are accessible through ... Read More

Overview A programmer may want to write three different programs. However, he realizes that some of the functionality needed for each program could be shared among them. Therefore, he decides to create a library containing these shared features. A library is basically a collection of code and data that other people can use. On Linux, archives (located at the.a file extension) contain compiled code, whereas shared objects (.so files) contain interpreted code. Here, we’ll examine how software runs under Linux and the purposes of the library and archive files. We’ll also see some examples of how we can create these ... Read More