ArchiveJune 2019

Flame graphs for Linux file systems

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Everybody gets to that moment when they need more space on the hard drive. You often just ask yourself: Where did the free space go from my disk? There are many tools that can be used for finding out the space you spend (one of my favorites is the du -sh command), but most of them are quite time consuming. These days, reading about the Linux performance system, I found a tool not only very useful...

Leanote, a Linux alternative for Evernote

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I started looking for a replacement solution for Evernote that can store local notes or a personal web server. And that was how I discovered Leanote – an open source “inspired by Evernote” (this is how the developer presents it), with several additional features: • local installation or personal web server; • a more powerful text editor and more options; • a markdown editor; •...

QEMU and KVM in Arch Linux

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KVM (Kernel-based Virtual Machine) is the native Virtualization System from RedHat; is a hypervisor built directly into the Linux kernel. The same system is also found in RedHat-derived distributions: CentOS, Scientific Linux, Oracle Linux or Fedora. KVM offers the ability to create and manage a lot of virtual machines on a single web host: the web host server that has one of the above mentioned...

How to use Helm in Kubernetes

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Think of Helm as a package manager: pacman in Arch Linux, apt-get in Ubuntu or yum/dnf in Red Hat/Fedora. Helm is developed by Deis and helps us manage K8s applications. With Helm Charts it has become a joke launching, maintaining, updating, reverting to a previous version, or deleting apps in Kubernetes. A chart is easy to create, maintain, and distribute. Charts are pre-configured Kubernetes...

Minikube, the easiest way to run Kubernetes locally

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Minikube runs a Kubernetes cluster with a single node inside a virtual machine on the personal computer. Therefore, there is a need to have virtualization on a personal machine with a KVM or VirtualBox hypervisor. The tutorial below is done on a Fedora and KVM system. Also, before installing Minikube, we need to install kubectl, one of the most used kubernetes tools. Installing kubectl Kubectl is...

Building a Kubernetes cluster (K8s) on CentOS 7 in a KVM

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Kubernetes is an open source tool for managing and orchestrating docker containers in a cluster of servers. Kubernetes (abbreviated k8s) was developed by Google and donated to the Cloud Native Computing Foundation. Kubernetes makes a separation between the servers on which the Linux distribution is installed and the applications running on these servers. Setting up a Kubernetes cluster involves...

Managing files in Linux: the cp command

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One of the most used commands in Linux is cp (abbreviated from copy). The cp command copies a file. Its syntax is: cp [options] destination source The source parameter can be one or more files. It represents the original file or files we want to copy. The destination option may be a single file (when we copy a single file) or even a directory when copying multiple files. Copy a single file to the...

Managing files in Linux: mv command

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Command mv (short of move) is used both to move files and folders from one place to the other, and also to rename them. Linux does not distinguish between these two types of operations (move and rename), as users do. The syntax of the mv command is as follows: mv [option] destination source The mv command accepts almost the same options as the cp command. However, mv can not be used with...

Managing files in Linux: ls command

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The ls command (list) displays the file names in a directory. The syntax of the ls command is simple: ls [options] [files] Both the command options and the list of files are optional. If we omit to write the list of files, the ls command will display the contents of the current directory (we will use the pwd command first to display the directory we are in). $ pwd $ ls If we want to display the...

Groupdel command – delete groups in Linux

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The easiest way to delete a group in Linux is using the groupdel command. The basic syntax is: groupdel group_name For example, the groupdel projects command deletes the project group. A group can also be deleted by editing the /etc/group or /etc/gshadow files if the latter is present by removing the line corresponding to that group. It is recommended to use the groupdel command because it checks...

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