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

Introduction You might have heard about the internet of things (IoT), but what exactly is it? Simply put, IoT is the network of physical objects such as cars, appliances, industrial equipment, medical devices, and so on that are embedded with electronics, software, sensors, and connectivity that enables them to collect and exchange data. Overview of IoT Frameworks There are a few different ways to build your connected devices and applications when it comes to the Internet of Things (IoT). One option is to use a pre-made IoT framework, saving you time and effort in development. Let’s take a look at ... Read More

In this article, we are going to learn about how to run Gunicorn on Docker. Before creating the docker container with the gunicorn functionalities, we must know some of the basics of web servers and gunicorn. Introduction to Gunicorn Let us suppose we have a web server that shows the output of a python code to the users. This web server will execute the python script each time a request came to it, this will cause it to restart, overload, and delay (heavy delay for huge scripts) in response. So the real problem here we have is a static server ... Read More

Before knowing how to run amd64 docker images on the arm64 host platform, we must know what this means. There is a term called multi-architecture or multi-platform docker container images. These images contain the ability to run on various base or host architectures provided at the time of containerization of the images. Need of Multiplatform images Suppose you are a DevOps engineer and you have to prepare a web-server for an IT company. You have an amd64 host platform but when you handed over the image to the company you came to know that the company only works on the ... Read More

Before getting into the docker container arguments we must know about python command line arguments and how they are accessed by the developer. Command line arguments are of great use when we want our python script to be controlled outside of the program. Access the python script’s command line arguments Step 1: Create a python script main.py Example # sys will allow us to access the passed arguments import sys # sys.argv[0] access the first argument passed that is the python script name print("File or Script Name is :", sys.argv[0]) # print arguments other than the file name ... Read More