Everyday Notes from a Linux Administrator
Red Hat Linux
You probably have heard and tried using speedtest.net to test you computer or smartphone internet speed. If you have your own server or VPS you can also test internet speed connection from the command-line using the speedtest-cli utility. On this tutorial, I’ll show how to install and use speedtest-cli to test your internet speed.
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Every Linux process has a process ID (PID) assigned to it. It is a unique identification number that is automatically assigned to each process when it is created in an operating system. A process is a running instance of a program. In this tutorial we’ll look into ways on how to find the PID of process.
This tutorial will walk through the troubleshooting and recovery of a failed disk on a Software RAID setup. Especially mirroring the boot partition which is important when replacing disk and making sure the OS boots up properly after replacement. This tutorial was done on Ubuntu 14.04 but should still work on other distributions such as RHEL and CentOS.
SSL secured websites or HTTPS has now become a must to have on website, especially those handling sensitive client information. Having a HTTPS enabled website means that a intruder can’t intrude to communication between users and website. HTTPS not only secures communication but is now a requirement for many new features like http2, which requires you to have https enabled on your server. Having a HTTPS enabled website also improves your Google SEO (Search Engine Optimization) ranking.
In this tutorial, we will discuss two methods on how we can redirect http traffic to https on Apache web servers.
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We might have come across a situation where we might want to rename user in Linux system, for whatever reasons. We can easily rename user in Linux and also we can rename the home directory or its UID as well.
In this short tutorial, we will be discussing these things only.
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Databases are arguably one of the main component of any modern application. And one of the most popular implementation of SQL databases is Mysql or the new replacement MariaDB. As a system administrator, you probably have installed and configured a database before. This tutorial will walk though setting up the master-slave replication of MariaDB.
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Every time you update your CentOS Linux and the update includes a new kernel image update the system will not remove your old kernel but it will cumulatively add new kernel to the top of your Linux kernel installed list. Normally, this does not present any issue to your running system and you are not required to take any action to remove any old and unused kernel images.
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Disks getting full on Linux is a common scenario any administrator have probably experienced. There are usually some large files in /var/log directory that can be compressed or deleted to save disk space. Have you ever experienced deleting a large log file and noticed that the disk usage remained the same ? It’s as if the file size usage is not released even though you’ve deleted it?
This scenario can happen if you deleted/renamed/moved an existing file that is currently in use by a running program. This usually happens on log files that are not rotated regularly and then when the file size becomes large, you deleted (or compressed) the file without even checking if it is in-use. Don’t worry, you can still recover your disk space as shown from the example below.
Continue reading “Recover disk usage after deleting large file in Linux”