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today I learned from tutorials, courses and from kb.txt, plus old content from sysadmin.md and video4admin.com

Get how many layers your Docker image is composed of
Chef recipe
Idempotence
Setup a Kubernetes cluster using kubeadm, Vagrant, Centos 7 and libvirt (KVM)
Container restart policies in docker-compose
What is a kernel system call
Chef Ohai
OpenSSH - generate public key from the private key
Test Docker image for vulnerabilities with Snyk
Hello world using Chef
Running pods in Kubernetes
Take screenshot of a region in Windows
Docker image creation and optimization Example 2
Docker image creation and optimization Example 1
Main keys in Kubernetes API object yaml file
Chef resource
Running an interactive shell in a container
Tagging an image for Docker Hub
Exploring the Kubernetes API
Chef Development Kit
Vagrant with libvirt on Debian testing
What are Linux capabiities
Linux kernel Control Groups (cgroups)
Linux kernel namespacing
Infrastructure as a Code
Stop Docker containers
lsblk
.vimrc for kubectl
Using bind mount directories in Docker
Fixing issue with black screen after suspending in XFCE
Vim: Text manipulation
Replace string with another string with regexp in Ansible
Docker custom search images examples
Vim: Status
Set CPU limitation to Docker containers
apg - a cli password generator
Setup Apache vhost with LetsEncrypt certificate on Debian
Vim: Recording macros
Set hard and soft memory limitation to Docker container
mail command in Linux - send email in cli
Run MongoDB and Mongo Express in Kubernetes
Vim: Searching and replacing
List resources that are bound or not bound to namespace in Kubernetes
Ansible code to add Grafana users
ohai values interpolation in Chef
Change default namespace in Kubernetes
Install Docker on Debian testing
Java process core dump
Integer division in Python
Detach from running Docker container
Vim: pasting
Docker compose file for Mongo and Mongo Express
nginx virtual host for reverse proxy
Run Mongo and Mongo Express using Docker
Install minikube with KVM on Debian testing
Show hidden files in Gnome
Tell Ansible to use a list of hosts rather than inventory file
Analyze file metadata with file command
Vim: delete
Formatting strings in Python
Remove NVIDIA drivers and install open-source Nouveau display drivers in Debian
Passing extra variables to Ansible playbook in a JSON format
Python list comporehension
vsftpd config for default installation
Show memory hardware information
Ansible role which use pinning instead of holding to keep the Ubuntu packages from being upgraded
Snake case
Example of formatting strings in Python
Vim basic modes
Fix MySQL error "Plugin caching_sha2_password could not be loaded"
Vertical format for docker ps
Prevent ssh from disconnecting on client side
Locals in Terraform
exec
Run gvim on a remote host
Get firewalld services on CentOS
for statement using dictionaries and macros in jinja2 templates with Ansible
Linux file types
Vim - substitute in multiple files
bash until
Temporary fix for black Google Chrome windows after suspend
About vi
Expire user password and force reset at next login in Linux
Create AWS S3 resource with Terraform using interpolation
Prepare an Ansible testing environment
Vim yank
bash if
What is continuous deployment
What is continuous delivery
What is continuous integration
What are Ansible variables
Vim visual mode
bash wildcards
Basic printf/scanf in C
Vim insert mode
jinja2 map filter
Delete a file from tar archive
for statement using dictionaries in jinja2 templates with Ansible
Configure OWASP scan with dependency check plugin in Jenkins pipeline project
Get help in Linux
Scan for writable directories with find
What are Ansible facts
vim - navigating the file
Hello world in C
Create default Ansible role directory structure with Molecule
Setup grafana with Cloudwatch without IAM user
jinja2 default filter
vim help
Legal C digraphs
jinja2 join filter
Go to the shell output in Midnight Commander
C comments
Installing C compiler on Linux
vim save and quit
for statement in Jinja2 templates with Ansible
Ansible load vault password from a file
if statement in Jinja2 templates with Ansible
Jenkins terms
C type casting
Working with lists in Ansible
Find files and directories with nouser and nogroup
Go to beginning and end of the file in nano
Run the OOM adjustments on all php-fpm childs
Uninstall VMWare Workstation in Debian
Grab all urls from saved html file with python and beautifulsoup
Network card firmware install in Debian
Display available versions of a package in Debian/Ubuntu
Set tab spaces to 2 in vim to edit yaml and python files
Ansible tasks plays and playbooks
Copy directory and preserve all permissions in Linux
YAML basics
Allow incoming SYN packets to all listening ports using iptables and Ansible
Uninstall validate_password plugin for MySQL
Lock user password
Enumerate fields for local credentials databases
Most used Desktop Environments
Linux boot process
Virtualbox replacement in Debian
Ansible role directory components
KVM clipboard sharing
Common tests in bash for conditional statements
REST clients
What is piping in bash
What is a Linux distribution
Suspend in older versions of Gnome
Init runlevels
Linux network commands
Enable windows title buttons (minimize, maximize) in Debian Gnome
View kernel messages in Linux
Listing devices in Linux
woeusb - burn Windows ISO to flash from Linux
Linux kernel modules tools
Download manager which monitors clipboard
Pseudo file systems in Linux
Create a temporary files in scripts
passwd shadow group files structure
Get the number of threads for a running process in Linux
Brackets in bash
Simulate a package installation with apt
Convert to lower case with tr
Things to do after creating systemd unit file
How to enable debug in bash script
Single and double quotes in bash
Enable line wrapping in nano
Crontab for MySQL backup
How to kill nginx caching
Create a bash function with parameters
Generate a sequence of numbers in bash
Get a proper list of services which are currently running
Routers, hubs and switches
Rename multiple files by pattern in bash with find
Get instance metadata in AWS
Generate file contents using cat, here-document and environment variables
Over 300GB logs size due to "AER PCIe Bus" errors
Disable automatic sleep in Debian testing
Resizing AWS EC2 partition
Read yaml values from encrypted file with ansible-vault using python
Check if string is present in usernames in multiple AWS accounts using awscli and jq
Quick way to create a dababase and user with password for MySQL/MariaDB
Monitor page load with PhantomJS, Nagios and Ruby
Several methods to write ISO to flash drive
Drop multiple measurements from InfluxDB database using a pattern
Archive all directory logs except today with find and gzip
Format strings in Terraform
Save results of MongoDB query in a JSON file
Check Elasticsearch status from Nagios
Don't log commonly missing files in nginx
Pack and delete only specified log files by template with tar seq and printf
Convert a MongoDB cloned server from replica set to a stand alone server
How to scroll inside screen
How to retrieve entire site via command line using wget
How to reset the password for any RabbitMQ user
Batch change passwords on multiple AWS accounts
Restart Gnome-shell without killing running applications
Executing bash and groovy commands on a Jenkins node
Modify default autogen retention policy in InfluxDB
How to remove "Send to device" in Chrome right click
Delete artifact from Nexus repository using REST API
Get IP address from console
Take a screenshot of a specific area in Gnome
What is cloud computing
Check password protected certificate expiration date with OpenSSL
Linux add swap space oneliner