Justin C. boxofrox

Disclaimer: Please follow this guide being aware of the fact that I'm not an expert regarding the things outlined below, however I made my best attempt. A few people in IRC confirmed it worked for them and the results looked acceptable.

Attention: After following all the steps run gdk-pixbuf-query-loaders --update-cache as root, this prevents various gdk-related bugs that have been reported in the last few hours. Symptoms are varied, and for Cinnamon the DE fails to start entirely while for XFCE the icon theme seemingly can't be changed anymore etc.

Check the gist's comments for any further tips and instructions, especially if you are running into problems!

Screenshots

Results after following the guide as of 11.01.2017 13:08:

How to generate a self-signed SAN SSL/TLS certificate using openssl

Generating a self-signed certificate is a common task and the command to generate one with openssl is well known and well documented. Generating a certificate that includes subjectAltName is not so straght forward however. The following example demonstrates how to generate a SAN certificate without making a permanent change to the openssl configuration.

Generate a list of all required DNS names, (Note: CN will be discarded).

$ export SAN="DNS:www.domain.localdomain,DNS:domain.localdomain"

Nixpkgs pinning example

This is an example of how to pin the version of nixpkgs in a package repo. The goal is to improve reproducibility, make sure all the developers use the same version of nixpkgs and also allow to share binary caches.

Usage

Put all these files in a nixpkgs folder and then in other derivations, instead of import <nixpkgs> {} use import ./path/to/nixpkgs {}

Keeping nixpkgs up to date

This is my take on a systemd#2741 work-around. The lack of native namespace joining makes it so you have to do a dance with systemd's version of private namespaces and iproute2's version. The portal_network.sh is my rendition of iproute2.
Credit to ian-kelling's code and comment in the systemd issue that inspired me to research this further. Looking at iproute2's source the bash script should be identical, including the private mount and bind mounts. This level of compatibility gives the administrator the ability to use ip -n portal ... for any subsequent commands.

Files are dash separated due to this being a gist (slashes aren't allowed). PLace the files in the correct locations then run the following:

systemctl enable portal.target portal.network.service whatever.service
systemctl restart systemd-networkd # if using the vlan files and such

Developing with Nix

This has been moved to the Matrix AI blog: https://matrix.ai/2018/03/24/developing-with-nix/

Note that if you just to compile a simple C program, and you don't want to fiddle with environments:

nix-shell --packages stdenv

Error and Exception Handling Techniques

http://lambda-the-ultimate.org/node/3896#comment-58374

Reposting here for safe keeping.

Error Codes

One of the return values is the error. Use when the goal is to cover-your-ass by ensuring that error handling is possible, even though you know any error handling or recovery would clutter the happy-path and thus ensure programmers are reluctant to admit to their existence at all.

This bash script updates a package version and source hash directly in the source files.

It uses unsafeGetAttrPos to find the files to edit, which in turn require to get access to the real attrset. This is why we have to define the overlays.

Nix Flake MVP

Goals

To provide Nix repositories with an easy and standard way to reference other Nix repositories.
To allow such references to be queried and updated automatically.
To provide a replacement for nix-channel, NIX_PATH and Hydra

ANSI Escape Sequences

Standard escape codes are prefixed with Escape:

Ctrl-Key: ^[
Octal: \033
Unicode: \u001b
Hexadecimal: \x1B
Decimal: 27

	#!/bin/bash
	MAC=false
	date -r "$now" +%Y-%m-%d &> /dev/null
	if [ "$?" -ne "0" ]; then echo "LINUX"; MAC=false; else echo 'MAC'; MAC=true; fi

	now=`date +%s`

	while true
	do
	if [ "$MAC" == "true" ]; then data=`date -r "$now" +%Y-%m-%d`; else data=`date -d @"$now" +%Y-%m-%d`; fi