Software &> Sysadmin &> Devops &> SRE

Month May 2022

Ansible inventory, best practices to manage ssh key with a bastion (jump host)

Ansible ssh key connection Refer to The advantages of an ssh key over a basic authentication are: no raw password (but you can encrypt passwords using ansible vault) one unique private key to connect to several nodes (but of… Continue Reading →

Public key authentication on Linux – best practices: a more secure way to connect to your hosts without login and password

Note: for the whole article, I will work with a linux user called ansible on a host called also…ansible! 🙂 ssh-keygen When you use ssh-keygen you will generate a private and public key pair. And you’ll have to choose which… Continue Reading →

Install ansible 5 inside a python virtual environment with python 3.10.4

Note: The following commands are for RockyLinux, RedHat, CentOS, on other distros it will be almost the same. I’ve made the choice to connect to a user called ansible, and inside his home directory I’ve created a directory called ansible,… Continue Reading →

Python and virtual environments on Linux OS

Install python 3.10.4 from source on Rocky Linux or CentOS The following commands are executed as a root user. Virtual Python environment You can install several virtual python environments on your Linux OS. It will allow you to deploy a… Continue Reading →

How to empty a file with cmd or powershell? (equivalent of linux: cat /dev/null > pathtofile)

cmd version: The file is now 0 byte size, and occupies 0 byte on disk. powershell version: In this case, the properties of the file show us it’s now 2 bytes size then not completely empty. And the file uses… Continue Reading →

Why CRLF on Linux can sometimes be displayed as ^M with line feed?

Firstly, it’s good to remember these following points: CR is for Carriage Return LF is for Line Feed On windows line endings are represented by CRLF (CR+LF) On Linux line endings are represented by LF In a shell script you… Continue Reading →

Chrome Refused to display ‘’ in a frame because it set ‘X-Frame-Options’ to ‘deny’.

In the DevTool of your web browser you have this kind of message because you’ve been to the url (or a completely different domain like that contains an HTML page which includes an iframe of This message… Continue Reading →

Equivalent of Linux tail -f inside windows powershell

-Wait signifies wait for new logs and display it -Tail 10 signifies display the last 10 lines from <my_log_file>

Send an email on Linux with CLI or shell script without installing anything (no ssmtp required)

Prerequisites Basic example without encoding headers Case of an existing SMTP server without authentication ( can be replaced by the domain name of your smtp server or its IP address): At the end you can see “\nSubject: TEST send mail… Continue Reading →

Shell script – Variables evaluation : display line endings \n and don’t cut your parameter function

How to pass string with several words and line endings \n as a parameter to a function Solution : Second test rst test : $myvar will be replaced by it’s value that contains a lot of words with spaces and… Continue Reading →

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