Overview The zip command is one of the most useful tools available on any operating system. It allows you to compress multiple files into a single compressed archive file. You can then decompress that archive file using the unzip command. This tutorial will show you how to use the zip command to create and extract archives. In this tutorial, we’ll be looking at the zip command-line tool in Linux. We will learn how to use it for creating and extracting archives. The zip command is a part of the GNU core utils package. It can be used to create and ... Read More

Overview As a Linux system administrator, dealing with processes is a frequent task. Generally, they're easy to stop, however in certain cases - when there are large numbers of processes within the same groups - additional steps might be needed. We’ll take a closer look at how to manage processes using the concept of “groups”. Also, how to terminate all processes that belong to one particular group. Process Groups A process grouping in Linux is a way that Linux processes share the same PIDs (process IDs). They are a set of related processes that share the same PIDs. Killing the ... Read More

Overview When using Linux, we often perform various operations on our own personal data. One common operation is to create an empty file of a specific size. There are many ways or command to achive this, here we’ll cover some of these methods − “dd” command dd − The dd command is a utility for copying files and converting the format of data. It can be used to create a file of a certain size by specifying the block size and the number of blocks with the bs and count options, respectively. The dd command reads data from an input ... Read More

Overview curl is a command line tool that supports many different types of websites including https sites. It can be used to connect to any website, but it's most commonly used for connecting to web servers and retrieving data from them. In this tutorial we will learn how to use curl to make an HTTPS connection to a website. We will also see how to retrieve the contents of a file using curl. We’ll look at using curl to call an HTTP endpoint via HTTPS. What is Curl? Curl is a command line tool that allows users to transfer data ... Read More

Overview This article examines how to total up numeric columns of data in a bash shell, looking at the bash tools available for the task and comparing their speed. Using The awk Tool We’ll start by calculating the sum of the values in a particular column using the awk (awk) program. $ awk '{Total=Total+$1} END{print "Total is: " Total}' numbers.csv Total is: 49471228 Let’s now take a look at the timing using the “time” command − $ time awk '{Total=Total+$1} END{print "Total is: " Total}' numbers.csv Total is: 49471228   real 0m0.228s user 0m0.141s sys 0m0.047s When The ... Read More

Overview Extracting a substring from a string is a basic and common operation of text processing in Linux. We're looking at different ways to extract substrings from strings using the Linux command line here. Extracting an Index-Based Substring Let’s first take a quick glance at how to extract index-based substring using four different methods. Using the cut command Using the awk command Using Bash’s substring expansion Using the expr command Next, we’ll see them in action. Using The cut Command We can extract characters starting at position N through position M from the input string using "cut" command. ... Read More

Overview Generally, packages are installed in the default directory. Depending on the system's Linux version, it might be necessary to use a different directory such as /usr or /user/local. We might also want to install a particular software application for a single user rather than for the entire system. We'll take a look at how to change where packages get installed by running make uninstall. Using ./configure Parameters When using autoconf/automake to build software packages, a configure script with several standard parameters and (sometimes) additional custom parameters is provided. Some packages don't use autoconf but they usually offer a compatible ... Read More

Introduction If you're working with Linux, there might be times when you'll want to copy several files at once and then remove some of them later. We're going to take a closer at several different methods for achieving such results. Renaming The Unwanted File You can rename the unwanted file so that it becomes a “.” (dot) file means hidden files, which means that mv won't be able to see it. After renaming the unwanted file using the asterisks, we’ll then use the regular expression to remove the rest of the files. /source_dir$ mv file5 .file5 /source_dir$ mv * ~/target_dir/ ... Read More

Overview When crontab runs a command, it doesn't read any environment variables from files like ~/.bashrc, ~/.bash_profile, etc. Because cron runs tasks from a non-interactive, non-login shell, it doesn't need an interactive user Some applications require environmental variables to function correctly. We’ll discuss different methods for loading environmental variables from a crontab. Setting the BASH_ENV Variable We can set environment variables for our shell scripts by using the BASH_ENV variable. We set it up so that when we run our jobs, they're executed by a shell script. We can set up our shell so that when we open a new ... Read More

Overview Tmux is a terminal multiplexing utility for Unix systems. It provides an interface between several programs running simultaneously on one computer. Tmux allows us to detach from any terminal sessions without killing them. We can then reattached to any of the terminal sessions later on. We’ll learn the tmux terminal emulator in Linux. Specifically, we’ll examine some of its features and commands. Installation You can install tmui on Debian-based Linux systems using the apt-get package manager. $ sudo apt-get update -qq $ sudo apt-get install -y tmux We can also use the yum command line tool to download ... Read More