srikanthmanda

#!/bin/bash

# Example:
# ./getopts-demo.sh -a42 -l Beeblebrox -c "Sector ZZ9 Plural Z Alpha" -f Zaphod

if [[ -z $1 ]]
then
  echo 'Usage: ./getopts-demo.sh -f <first name> -l <last name> -a <age> -g <gender> -c <country>'
  exit 1
fi

srikanthmanda

# iSH app: https://ish.app/
# Installing Alpine Linux APK packages: https://wiki.alpinelinux.org/wiki/Alpine_newbie_apk_packages#install_basic_tools
# BusyBox: https://busybox.net/

# Update APK repositories and upgrade packages
apk update
apk upgrade

# Note: iSH comes packaged with BusyBox `grep`, `less` and `sed`
which grep less sed > ~/original_versions.log

srikanthmanda

TLS/SSL & OpenSSL

Brief notes on TLS/SSL private keys and certificates, their various formats and converting them to different formats using OpenSSL.

Resources & References

• OpenSSL Commands: https://www.openssl.org/docs/man1.1.1/man1/ (current stable version - v1.1.1)
• OpenSSL Cookbook: https://www.feistyduck.com/books/openssl-cookbook/
• Public-key Cryptography Standards (PKCS): https://en.wikipedia.org/wiki/PKCS
• X.509 certificates filename extensions: https://en.wikipedia.org/wiki/X.509#Certificate_filename_extensions

srikanthmanda

Secure Communications

What? Keeping secrets secret.

How? Encryption.

What is Encryption?

Turning something intelligible i.e., which can be understood/comprehended easily, into something unintelligible i.e., meaningless.

srikanthmanda

// This file was initially generated by Windows Terminal 1.1.2233.0
// It should still be usable in newer versions, but newer versions might have additional
// settings, help text, or changes that you will not see unless you clear this file
// and let us generate a new one for you.

// To view the default settings, hold "alt" while clicking on the "Settings" button.
// For documentation on these settings, see: https://aka.ms/terminal-documentation
{
    "$schema": "https://aka.ms/terminal-profiles-schema",

srikanthmanda

VS Code

• CTRL + SHIFT + L: Select word under cursor
• SHIFT + ALT + RIGHT ARROW: Expand selection

srikanthmanda

Git Tips

Amend a Commit

git commit -a -m "wrong commit, needs changes"    # commit only staged changes, miss untracked changes
git add forgotten_file edited_file ...            # stage the changes to fix previous commit
git commit --amend --no-edit                      # commit staged changes, without editing commit message
git commit --amend -m "revised commit message"    # edit commit message, and commits staged changes if any

srikanthmanda

HTML Tags

• <mark> tag applies background colour to highlight content.
• <kbd> tag is to indicate keyboard strokes/keys, usually user input.

srikanthmanda

Infrequently Used Commands

PowerShell

Print PowerShell environment variable

$env:<variable>

Python