Neeraj Kanhere neerajkanhere

Create Root CA (Done once)

Last update: Nov 2025.

Create Root Key

Attention: this is the key used to sign the certificate requests, anyone holding this can sign certificates on your behalf. So keep it in a safe place!

openssl ecparam -genkey -name secp384r1 | openssl ec -aes256 -out rootCA.key

Useful Examples of ffmpeg and GNU parallel on the command-line:

Transcoding FLAC music to Opus:

ffmpeg is a highly useful application for converting music and videos. However, audio transcoding is limited to a a single core. If you have a large FLAC archive and you wanted to compress it into the efficient Opus codec, it would take forever with the fastest processor to complete, unless you were to take advantage of all cores in your CPU.

parallel 'ffmpeg -v 0 -i "{}" -c:a libopus -b:a 128k "{.}.opus"' ::: $(find -type f -name '*.flac')

Transcoding Videos to VP9:

List all Git repository objects by size

Summary
Example

Summary

Bash script which will:

Iterate all commits made within a Git repository.

	[Unit]
	Description=X Virtual Frame Buffer Service
	After=network.target

	[Service]
	ExecStart=/usr/bin/Xvfb :99 -screen 0 1024x768x24

	[Install]
	WantedBy=multi-user.target

	import logging
	import fcntl
	from contextlib import contextmanager

	@contextmanager
	def locked_open(filename, mode='r'):
	"""locked_open(filename, mode='r') -> <open file object>

	Context manager that on entry opens the path `filename`, using `mode`
	(default: `r`), and applies an advisory write lock on the file which

	#!/usr/bin/python3
	"""An interactive Python interpreter to play with GTK+ without blocking the console

	Usage:
	./pygigtk.py

	You don't need to call 'Gtk.main' in the console, just start using Gtk, such as
	creating a window and 'show_all' it. Gtk, GObject, etc have been imported.

	Author: fikr4n <github.com/fikr4n>

	GCC security related flags reference.

	Source material:
	http://security.stackexchange.com/questions/24444/what-is-the-most-hardened-set-of-options-for-gcc-compiling-c-c
	https://wiki.gentoo.org/wiki/Hardened_Gentoo
	https://wiki.debian.org/Hardening

	===================================================================================
	GCC Security related flags and options:

	//
	// Debug Helpers
	//
	// Copyright (c) 2015 - 2017 Sean Farrell <sean.farrell@rioki.org>
	//
	// Permission is hereby granted, free of charge, to any person obtaining a copy
	// of this software and associated documentation files (the "Software"), to deal
	// in the Software without restriction, including without limitation the rights
	// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	// copies of the Software, and to permit persons to whom the Software is

	#ifndef _POLYNOMIAL_REGRESSION_H
	#define _POLYNOMIAL_REGRESSION_H __POLYNOMIAL_REGRESSION_H
	/**
	* PURPOSE:
	*
	* Polynomial Regression aims to fit a non-linear relationship to a set of
	* points. It approximates this by solving a series of linear equations using
	* a least-squares approach.
	*
	* We can model the expected value y as an nth degree polynomial, yielding