How to manage DigitalOcean VPS droplets from the command line on Linux

DigitalOcean is one of the hottest new kids in the block in the cloud VPS hosting market. While not offering as comprehensive service portfolio as Amazon Web Services and the likes, DigitalOcean is already a strong contender for the best Linux-based cloud VPS service targeted at small businesses and developers, thanks to their competitive pricing […]
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How to check RPM package dependencies on Fedora, CentOS or RHEL

A typical RPM package on Red Hat-based systems requires all its dependent packages be installed to function properly. For end users, the complexity of such RPM dependency is hidden by package managers (e.g., yum or DNF) during package install/upgrade/removal process. However, if you are a sysadmin or a RPM maintainer, you need to be well-versed […]
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How to set up two-factor authentication for SSH login on Linux

With many high-profile password leaks nowadays, there is a lot of buzz in the industry on “multi-factor” authentication. In a multi-factor authentication system, users are required to go through two distinct authentication procedures: providing something they know (e.g., username/password), and leveraging something they have “physical” access to (e.g., one-time passcode generated by their mobile phone). […]
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How to repair a crashed WordPress database table

A WordPress database may experience failure and corruption under various circumstances. One of common problems with it is “crashed database.” When that happens, you will find the following error in WordPress error log: WordPress database error Table ‘./my_home/wp_posts’ is marked as crashed and last (automatic?) repair failed for query SELECT post_date_gmt FROM wp_posts WHERE post_status […]
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How to sync Microsoft OneDrive on Linux

OneDrive (previously known as SkyDrive) is a popular cloud storage offering from Microsoft. Currently OneDrive offers 7GB free storage for every new signup. As you can imagine, OneDrive is well integrated with other Microsoft software products. Microsoft also offers a standalone OneDrive client which automatically backs up pictures and videos taken by a camera to […]
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How to monitor Nginx web server from the command line in real time

Once Nginx web server is up and running in a production environment, you will want to monitor its activity in real time. In fact, general network monitoring software such as Nagios, Zabbix, Munin provide support for real-time Nginx monitoring. However, if you do not need comprehensive reporting capabilities or long-term statistics offered by such tools, […]
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How to take a screenshot from the command line on Linux

There are various flavors of Linux screenshot utilities, including desktop-specific screenshot programs (e.g., KSnapshot for KDE, gnome-screenshot for GNOME, Screenshooter for Xfce), or general screenshot utilities (e.g., Shutter). One of unique screenshot utilities is Scrot (short for “SCReen shOT”), which is a command-line screenshot utility. While its interface is minimalistic, Scrot is, feature-wise, as powerful […]
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How to manage passwords from the command line on Linux

With password-based authentication so prevalent online these days, you may need or already use some sort of password management tool to keep track of all the passwords you are using. There are various online or offline services or software tools for that matter, and they vary in terms of their sophistication, user interface or target […]
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How to run Docker containers on CentOS or Fedora

Lately Docker has emerged as a key technology for deploying applications in the cloud environment. Compared to traditional hardware virtualization, Docker-based container sandbox provides a number of advantages for application deployment environment, such as lightweight isolation, deployment portability, ease of maintenance, etc. Now Red Hat is steering community efforts in streamlining the management and deployment […]
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