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Yum check-update return codes

When using yum check-update in Ansible Playbook, it may failed sometimes because of the following reasons:

• yum check-update returns exit value of 100 if there are packages available for an update. Also returns a list of the packages to be updated in list format.
• yum check-update returns 0 if no packages are available for update.
• yum check-update returns 1 if an error occurred.

The easiest way is to use ignore_error: yes in your that task, but this will also cause other return codes to be ignored and your playbook will continue execute.

The better way is to add the following line:

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Ansible Tips and Tricks

A collection of some of my useful Ansible Tips and Tricks.

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Configure default Ansible user and Python interpreter

In /etc/ansible/ansible.cfg, under [defaults], add:

remote_user=<ansible-user>
interpreter_python=/usr/bin/python3

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Generate Linux CSR

This guide will show you how to generate certificate signing request (CSR) file in Linux system.
The CSR file generated will be sent and signed by the CA server.

Subject Alternative Name (SAN) is required by chromium-based browers such as Chrome or Microsoft Edge.
Without SAN, chromium-based browers will still display the SSL error: ERR_CERT_COMMON_NAME_INVALID.

Generate client private key:
openssl genrsa -out myhost.example.com.key 2048

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Regular Expression Tips and Tricks

A collection of some of my useful Regular Expression Tips and Tricks.

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Detect all variants of text

Given the following list of input:

1test2
test2
1test

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Ansible References

Playbook Keywords: https://docs.ansible.com/ansible/latest/reference_appendices/playbooks_keywords.html
Return Values: https://docs.ansible.com/ansible/latest/reference_appendices/common_return_values.html
Special Variables: https://docs.ansible.com/ansible/latest/reference_appendices/special_variables.html

List of my common default variables

Variable	Output

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Free DNS

https://nip.io is a dead simple wildcard DNS for any IP Address without any registration.
nip.io maps <anything>[.-]<IP Address>.nip.io to .
Can be useful for application deployments with apache/nginx.

Usage examples

To give URL for your ip 192.168.0.1, you can have the following URLs:

• 192.168.0.1.nip.io
• anything.192.168.0.1.nip.io

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Linux CLI to download releases from GitHub Repo

• Use curl to get the JSON response for the latest release
• Use grep to find the line containing file URL
• Use cut and tr to extract the URL
• Use wget to download it

curl -s https://api.github.com/repos/jgm/pandoc/releases/latest \
| grep "browser_download_url.*deb" \

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Linux Tips and Tricks

A collection of some of my useful Linux Tips and Tricks.

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Check if a restart is needed

If a restart is required in a Linux instance, it will add a file: /var/run/reboot-required.
It contains the message *** System restart required ***.

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Check and Auto-Fix File System

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Screen

Screen or GNU Screen is a terminal multiplexer. In other words, it means that you can start a screen session and then open any number of windows (virtual terminals) inside that session. Processes running in Screen will continue to run when their window is not visible even if you get disconnected.

Usage

Start a Named Session

screen -S <session_name>

List all Sessions

screen -list

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Access GitHub Repo with SSH Keys

1. Generate a SSH key:
   ssh-keygen -t ed25519 -C "your_email@example.com"
   OR
   For legacy system that doesn't support the Ed25519 algorithm:
   ssh-keygen -t rsa -b 4096 -C "your_email@example.com"
   https://docs.github.com/en/authentication/connecting-to-github-with-ssh/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent

2. Plant the Public key for:-