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Articles by Vivek Gite
How to Copy Hard Disk to Another in Linux Using the dd Command
How can I copy one hard disk to another using the dd, ddrescue, or dcfldd commands? You can copy the disk in raw format using the dd command. It will copy the partition table, bootloader, data, and all partitions within this disk. For example, you can copy /dev/sda to /dev/sdb (same size) using the following dd command. Please note that the dd should be complete with no errors on screen, except output the number of records read and written.
lnav - Awesome terminal log file viewer for Linux and Unix
It is no secret that whether you are a developer or sysadmin, you need to use log files to troubleshoot errors on your Linux and Unix systems. You use tools like grep, tail, cat, or journalctl to view log files. However, you may need help with so many log files. These essential Unix tools are suitable for basic text but fall short when dealing with many log files. You can get tired from sifting through endless lines of log files.
How do I find out my timezone in Linux?
You can find the timezone in Linux using the command line. The easiest way to do this is to type the “timedatectl” command and look for the “timezone” line when using modern Linux distros with systemd. There are other commands and ways to temporarily switch to a new timezone for date calculations. Support nixCraft! nixCraft is a privacy-focused, Ad-free, and reader-supported site. Support independent tech content. Share this page on social media or become a Patron! What is a time zone?
How to block AI Crawler Bots using robots.txt file
Are you a content creator or a blog author who generates unique, high-quality content for a living? Have you noticed that generative AI platforms like OpenAI or CCBot use your content to train their algorithms without your consent? Don’t worry! You can block these AI crawlers from accessing your website or blog by using the robots.txt file. nixCraft: Privacy First, Reader Supported nixCraft is a one-person operation. I create all the content myself, with no help from AI or ML.
How to install wget on Fedora Linux using the dnf command
Wget is a command-line tool to download files from the Internet or local servers. It is not a graphical user interface (GUI) program, and it must be used by typing commands into a terminal application. You can download files from the web. It supports HTTP, HTTPS, FTP, and other protocols. It can mirror entire websites or directories. Wget can resume downloads interrupted due to a network error or a power outage. Wget can start the download again from where it left off.
How to install ZFS in Debian 12 "Bookworm"
Here is a quick tutorial on installing ZFS support in Debian Linux 12 “Bookworm” using “apt” or “apt-get” command-line option. Tutorial details Difficulty level Easy Root privileges Yes Requirements Linux terminal Category Package Manager OS compatibility Debian β’ Linux Est. reading time 3 minutes nixCraft: Privacy First, Reader Supported nixCraft is a one-person operation. I create all the content myself, with no help from AI or ML. I keep the content accurate and up-to-date.
How to upgrade FreeBSD 13.1 to 13.2 release
My family of 4 went to LongHorn Steakhouse for the first time, and our $150 dinner felt like an incredible value
How to install OpenSSH server on Alpine Linux (including Docker)
Author: Vivek Gite Last updated: October 19, 2021 comments This quick tutorial explains how to install and set up OpenSSH (SSHD) server and client on the Alpine Linux system. Further, you will learn how to build a Docker Linux container running sshd server based upon Alpine Linux image too. Tutorial details Difficulty level Easy Root privileges Yes Requirements Alpine Linux Est.
How to audit SSH server and client config on Linux/Unix
All developers and Unix users know how to use an ssh client. OpenSSH is a widely used implementation of Secure Shell (SSH) Internet communication protocol. Back in the old days, Unix folks used Telnet which was insecure. On the other hand, SSH allows exchanging data using a secure channel between two hosts. Therefore, every Linux and Unix server running cloud or at home needs an OpenSSH server for management and IT automation.
How to set up ZFS ARC size on FreeBSD
When working with FreeBSD and ZFS, you will run into ZFS cache size problems. Not all FreeBSD servers are file servers. Some servers act as backup servers. Others might run Linux and Windows VM where you want those guest VMs to manage their own caching. It would help if you had tons of RAM for ZFS, but you may not have that luxury in real life. This page explains how to set up ZFS arc size on FreeBSD to work with less RAM to avoid the computer running out of memory in the kernel.
Interview with curl creator & software developer Daniel Stenberg
Even if you do not use the curl command daily, the chances are high that you are still using curl and don’t know. IoT and tons of other services on the Internet depend upon libcurl for network operations. Daniel Stenberg is a Swedish software developer, recipient of the Polhem Prize 2017, on cURL. Recently I did a quick Q and A with Daniel about starting the curl project and his daily workflow. Who are you, and what do you do? I’m Daniel Stenberg.
How To Install EPEL Repo on an RHEL 8
How do I install the extra repositories such as Fedora EPEL repo on an Red Hat Enterprise Linux server version 8? You can easily install various packages by configuring an RHEL 8 system to use Fedora EPEL repos and third party packages. Please note that these packages are not officially supported by Red Hat, Inc, but provides many popular packages and apps.
How to install Dart on Linux and set up VIM as IDE
Dart is easy to use BSD licensed programming language to build mobile, desktop, server, and web apps. Google creates and maintains the Dart ecosystem. It follows C-style syntax. We can compile code either to the native platform or JavaScript. Flutter allows building iOS/Android mobile and desktop/web apps from a single code base. Let us see how to install Dart programming language on a Debian or Ubuntu Linux and set vim as IDE.
Adding spice to your sudo session with a lecture file on Linux or Unix
Despite some severe bugs in sudo, it remains the defacto tool to gain root shell or run command as another user on Linux, macOS, and Unix-like systems. The sudo command allows the system administrator to grant an individual user access to unprivileged commands. For instance, I can give developers the ability to restart the Apache webserver or PHP/Python process on a Linux server. Let us see how to remind developers and unprivileged users about the power of sudo for fun and profit.
How to remove all old and outdated brew packages on MacOS
Author: Vivek Gite Last updated: February 5, 2017 comments I am using Homebrew to install packages on MacOS Sierra or Mac OS X. I noticed multiple version of bash or curl installed in /usr/local/Cellar/bash/. How can I delete an outdated version of brew packages and only keep the latest version on my system? First, open the Terminal application.
Linode cloud firewall: Do you need it to protect the Linux server?
Linode is an original cloud platform and founded before AWS. Back then, we used to call them VPS (Virtual Private Server). Recently they added a new firewall feature to control network access to my Linode server from the Cloud. Let us test drive Linode cloud firewall. What is a Linode cloud firewall? A firewall is nothing but simple rules that filters out malicious traffic reaching your Linux server or network. We use a firewall to block and allows network traffic as per our needs.
How to remove carriage return in Linux or Unix
How do I remove all the carriage returns \r (^M) from a file in Unix using the command-line options? A carriage return is nothing but a control character used to reset a device’s position to the beginning of a text line. In other words, whenever you hit the [Enter] key, you generate carriage return. It is a newline concept. Please note that in ASCII and Unicode, the carriage return is defined as 13. So you may see it as control+M (^M).
Linux Desktop Fun: Bonsai tree generator for CLI lovers
Bonsai (盆栽) is nothing but planting in a try. It is old age Japanese art of growing small trees in pots. Now you can do that with your Linux or Unix terminal easily for fun and profit. Let us look into the Bonsai tree generator called cbonsai created in Clang and Bash. Linux Desktop Fun: Bonsai tree generator for CLI lovers cbonsai is a free and open-source bonsai tree generator, written in C programming language using ncurses.
Critical bug in sudo puts Linux and Unix systems at risk
Author: Vivek Gite Last updated: January 27, 2021 comments Any logged-in unprivileged user can abuse an old bug in sudo to gain root privileges. It was rated as an important security issue for Linux and Unix-like operating systems. The Qualys research team has discovered the heap overflow vulnerability in sudo itself has been hiding in plain sight for nearly 10 years. The bug allows any local users to gain root access without authentication (no user’s password needed).
Raspberry Pi Pico released and available at $4 only
Author: Vivek Gite Last updated: January 21, 2021 comments Last year, the Raspberry Foundation also released a brand new version of the Raspberry PI PC (personal computer), and it is directly built into a small-sized keyboard. Now there is more good news for hackers and hardware developers. They just announced their first microcontroller-based product named Raspberry Pi Pico. This small device is priced at only US $4. Unbelievable price.
How To Exit Vim Text Editor Command
Author: Vivek Gite Last updated: February 13, 2020 comments I am a new Linux and Unix user. How do I exit the VIM text editor on a Linux/Unix-like operating systems? How to exit Vim editor? Vi or vim is a text editor for Linux and Unix-like operating systems. It can be used to edit all kinds of plain text files. It is especially useful for editing programs, scrpits or system configuration files located in /etc/ or /usr/local/etc/ directories.
How to Check and Print PHP Version on Linux / Unix
How do I find out PHP version under Linux operating systems? What command do I need to type to show the PHP version under Unix-like systems? How to find out what PHP version is installed on my server when I can now login using the ssh command and check the PHP version? PHP is a server-side programming language often used with Apache or Nginx server. Popular apps like WordPress, MediaWiki, and other need PHP. Let us see, how to check and print PHP version installed on your Linux or Unix server.
How To Add, Delete, Grant Sudo Privileges to user on FreeBSD
I‘m setting up a new FreeBSD server. I do not want to use a default root user who has full system access. How can I setup and grant sudo privileges to users on a FreeBSD VPS or server? How do I create a sudo user on FreeBSD 11.x/12.x/13.x? The root account has full system level access and usually reserved for admin tasks only. The sudo command allows a very small delegation of power to users other than the root user.
Significant vulnerabilities that crippled IT world this decade (2010-2020)
The last ten years in the computer and IT security world are crippled with so many vulnerabilities. We saw massive cloud computing adoption and end-users using mobile devices with high speed 4G LTE networks. A threat actor may have exploited such weakness in modern computers and networks. Let us look into top vulnerabilities and the attack surface in this decade (2010-2020) that affected Linux/Unix, macOS, IT, cloud-computing, and computers in general.
How To rollback an apt-get/apt upgrade on Debian/Ubuntu Linux
Rolling back to the previous version may solve the problem or free the disk space. Both CentOS/RHEL support rollback feature, but I learned hard way both Debian and Ubuntu does not support rollback feature yet. Know the problem before choosing the solution I remotely administer a Ubuntu 14.04.3 LTS server in one of those dirt cheap clouds, and I will periodically use apt-get command/apt command to install packages or do upgrades.
6 awesome text editors for Linux, macOS, and BSD CLI users
A text editor is an essential tool for both developers and sysadmin, especially when dealing with text based sessions. We use a text editor to create, edit, and update text. A text editor is used for many things. Some use them to write documents. Some people write code and others use it to edit Linux and Unix configuration files locally or remote servers running in the cloud. Let us see the top 6 text editors for Linux, macOS, and Unix command-line users/developers.
How to change LUKS passphrase in Linux
We use encryption to protect mobile devices. For instance, I always use LUKS disk encryption to protect all files stored on my SSD. Dm-crypt (Cryptsetup and LUKS) open-source disk encryption is transparent disk encryption and a great way to keep your data secure. However, changing passphrase is a bit of a challenge for new Linux users and developers.
How to restart CentOS or RHEL server safely
I use the reboot command to reboot our PostgreSQL server running on RHEL 7. We have a development server running on CentOS 7 too. However, sometimes I noticed database corruption or file issues. Is there is a safe reboot command that will do a graceful reboot for our CentOS or RHEL 7 server without causing any issues? What is the best way to appropriately restart CentOS/RHEL over ssh? There is no graceful shutdown or restart.
FreeBSD send mail with attachments
Author: Vivek Gite Last updated: December 18, 2020 comments I need to send a few reports everyday as a mail attachment. I’m using FreeBSD 6.2/7.x/8.x/9.x/10.x/11.x/12.x+ server. How do I send mail from a command line or a shell script when using FreeBSD Unix server?? You can easily send email attachment using mutt mail client. It works from command line or a shell prompt. However mutt is not installed by default. You need to install mutt command.
bpytop - Awesome Linux, macOS and FreeBSD resource monitor
The bashtop is an impressive Linux resource monitor that shows usage and stats for processor, memory, disks, and network. However, it suffers from bash itself, and cross-platform support is a nightmare. Now we have the Python port of bashtop. We can use a resource monitor that shows usage and stats for CPU, RAM, SSD (hard disk), network, and processes information in a lovely format.
CentOS Linux 8 will end in 2021 and shifts focus to CentOS Stream
CentOS is an acronym for Community Enterprise Operating System, and it is a 100% rebuild of RHEL (Red Hat Enterprise Linux). While RHEL costs money, CentOS offered as a free community-supported enterprise Linux distro. Developers and companies who are good at Linux and don’t want to pay RHEL support fees always selected CentOS to save money and get enterprise-class software. However, the free ride is over. Red Hat announced that CentOS Linux 8, as a rebuild of RHEL 8, will end at 2021.
How to convert pdf to image on Linux command line
I have many PDF files, and I need to convert them to a png file format, add a border to those images, and convert back all those images to pdf format. How can I convert pdf to image format on Linux and vice versa using the CLI? Portable Document Format (PDF) files are typically used everywhere; however, manipulating them via the Linux command line is hard. On the other hand, managing images is easy on Linux.
Linux GPU Monitoring and Diagnostic Commands Line Tools
A video card is a special circuit board that controls what is displayed on a computer monitor. It is also called a graphics processing unit (GPU), which calculates 3D images and graphics for Linux gaming and other usages. Let us see the top 7 Linux GPU monitoring and diagnostic command-line tools to solve issues. The following tools work on Linux for GPU monitoring and diagnostic purposes and other operating systems such as FreeBSD.
How to install MySQL server on Debian 10 Linux
How can I install MySQL server 8.0 on Debian 10 LTS Linux server? How do I add a new MySQL user and database on the newly set up Debian server running on AWS EC2 server? Oracle MySQL server version 8.0 is an open-source and free database used by most web apps and sites on the Internet. Typically MySQL is part of the LAMP (Linux, Apache/Nginx, MySQL, Perl/Python/PHP) stack. Popular opensource software such as WordPress, MediaWiki, and others heavily used by MySQL as a database storage engine.
Raspberry Pi 400 Desktop PC: Complete specs and pricing
Author: Vivek Gite Last updated: November 2, 2020 comments The Raspberry Foundation released a brand new version of the Raspberry PI PC (personal computer), and it is directly built into a small-sized keyboard. The Raspberry Pi 4 model was released in June 2019, and the 8GiB version recently. Let us see Raspberry Pi 400 technical specification and other details. From the blog post: Raspberry Pi has always been a PC company.
Linux / UNIX Desktop Fun: Terminal ASCII Aquarium
Author: Vivek Gite Last updated: October 21, 2020 comments You can now enjoy mysteries of the sea from the safety of your own terminal using ASCIIQuarium. It is an aquarium/sea animation in ASCII art created using perl. Install Term::Animation Fedora Linux user simply run the following dnf command: $ sudo dnf install asciiquarium Debian/Ubuntu Linux install Terminal ASCII Aquarium First, you need to install Perl module called Term-Animation.
Install Speedtest-cli On a FreeBSD To Check Internet Speed
I am using the FreeBSD system. How do I install Speedtest-cli on a FreeBSD Unix system for checking the Internet speed? Speedtest CLI allows FreeBSD users to test Internet speed using the command line. This command is meant for software developers, system administrators, and computer enthusiasts alike. It will enable us to measure internet connection performance metrics like download, upload, latency, and packet loss natively without relying on a web browser.
Alpine Linux set up WireGuard VPN server
How do I install and set up WireGuard VPN server on an Alpine Linux cloud server? How can I configure Alpine Linux as the WireGuard VPN server? How can I configure snat to route all VPN traffic on my Alpine Linux? Tutorial details Difficulty Advanced (rss) Root privileges Yes Requirements Alpine Linux Time 20m WireGuard is a free, open-source advanced, and high-speed VPN with state-of-the-art cryptography. It is quicker and simpler as compared to IPSec and OpenVPN implementations.
How To Set Up a Firewall with Awall on Alpine Linux
Alpine Wall (Awall) is an easy to use interace to iptables for Alpine Linux users. While iptables and ip6tables is an excellent command, it can be challenging for new Alpine Linux users. The awall tool has easy to follow high-level concepts such as zones, limits, policies, and a single source for both IPv4 and IPv6. This tutorial will show you how to set up a firewall with Awall on Alpine Linux.
How to find and delete directory recursively on Linux/Unix
I type ‘find . -type d -iname foo -delete‘ command to find all foo directories and delete them. However, I am getting an error message that read as find: cannot delete './hourly.4/data/foo': Directory not empty on Linux server. How do I find and delete directories based on find command output on Linux or Unix-like system recursively? The -delete option remove the DIRECTORY(ies), if they are empty. You need to use the -exec option to delete all directories and its contents. The syntax is as follows.
tmpmail - A temporary email right from Linux / Unix terminal
Author: Vivek Gite Last updated: September 14, 2020 comments Are you looking to send a temporary email right from your Linux or Unix terminal? Look no further. Try tmpmail command-line utility that allows you to generate a temporary email address for sending and receiving emails. Underneath the script uses 1secmail’s API to receive the emails. Why use a disposable email from the terminal or web? Throwaway email often used to send and receive to avoid SPAM.
How to Install Java on Ubuntu 20.04 LTS Linux
Can you explain how to install Java on Ubuntu 20.04 LTS Linux system? Java is one of the most popular software and specifications initially created by James Gosling at Sun Microsystems. We can create a cross-platform application in Java for mobile phones or desktop users. Currently, Java is owned by Oracle Corporation. OpenJDK and Oracle Java are the most prominent implementation of Java specifications. Oracle Java comes with restrictive a License and is preferred by enterprise users.
How to create a Linux swap file
Author: Vivek Gite Last updated: September 10, 2020 comments I am a new Linux system developer and user. How do I create a Linux swap file from the command line option for my cloud server? How can I add swap space on my Ubuntu 20.04 LTS or CentOS Linux 7/8 server? Swap space is nothing but disk, partition, or file control by the Linux kernel memory subsystem. The Linux kernel uses swap space when the server starts to run out of physical RAM (Random-access memory).
How to install kotlin programming language on Ubuntu/Debian Linux
Author: Vivek Gite Last updated: September 8, 2020 comment How do I install the latest version of kotlin programming language on Ubuntu or Debian Linux system? Kotlin is a free and open source statically-typed programming language. It runs on the JVM, and one can compile to JavaScript source code. Kotlin is similar to Apple’s Swift. One can write server-side or Android apps in it.
How to check if CentOS / RHEL needs a full reboot
Author: Vivek Gite Last updated: September 8, 2020 comments I am using a CentOS/RHEL 6/7/8 server. How do I check from the command line if a reboot is required for my CentOS host? How do I check if a host powered by CentOS Enterprise Linux needs to reboot after running the yum update command? We can quickly check if CentOS / RHEL needs reboot using a command-line option. Let us find out whether a full CentOS Linux reboot is needed and which Linux services need to be restarted on the host.
How to use ssh-agent for authentication on Linux / Unix
How do I use the ssh-agent command for non-interactive authentication on Linux and Unix-like systems such as macOS or FreeBSD desktop? My private key is protected with a passphrase or password. So I need have to enter the passphrase to use the ssh private key for authentication multiple times. How can I tell ssh ask the passphrase one time only? You need to use the ssh-agent command. It would hold your private keys used for ssh public key authentication.
Curl Shell Script To Purge Cache From Stackpath CDN
A content delivery network or content distribution network (CDN) is a system of servers containing copies of data, placed at various points in a network so as to maximize bandwidth for access to the data from clients throughout the network. Please note that the following script will only work with Stackpath CDN. You need to get API access keys using stackpath portal. Curl Shell Script To Purge Cache From Stackpath CDN Download the following script.
How to upgrade OpenSUSE 15.1 to 15.2 using the CLI
The latest OpenSUSE version is 15.2 and is an opportunity for both desktop and server users on the previous 15.1 release to update OpenSUSE Linux to get the newest software stack. It is easy to follow the procedure to upgrade OpenSUSE 15.1 to 15.2. In this tutorial, we will explain how to upgrade OpenSUSE 15.1 to 15.2. Step 1. Preparations – Backup everything You must back up all data and config files before typing any of the following commands.
How to install htop on Debian Linux using apt-get
I am a new user of Debian operating system. How do I install htop on Debian using the apt command or apt-get command? htop is nothing but Interactive process viewer for Debian Linux system. It is just like default top command with an additional set of options and better colorful display on the screen. Very useful for developers and new system users. This page shows how to install htop on Debian using command line options.
How to enable firewalld logging for denied packets on Linux
How do I enable FirewallD logging for denied packets on Linux operating systems so that I can view all dropped packets information? How can I view a log of the traffic blocked by FirewallD under a CentOS/RHEL (Red Hat Enterprise Linux)/Suse/OpenSUSE Linux? The firewalld gives a dynamically managed Linux firewall to protect your network connections, services, and interfaces.
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