Recent content on Codrut Constantin Gusoi

 Prerequisites
 
 
 Link to heading 
 
 
 Go into root mode: 
 sudo -i
 Look for your drive: 
 lsblk -f
 
 # NAME FSTYPE LABEL 
 # nvme0n1 
 # ├─nvme0n1p1 vfat EFI 
 # └─nvme0n1p2 crypto_LUKS 
 You should have: 
 
 nvme0n1p1 → EFI partition 
 nvme0n1p2 → root LUKS 
 
 
 Usage
 
 
 Link to heading…

 Prereqisites
 
 
 Link to heading 
 
 
 sudo pacman -S qrencode
 Also make sure you have a proper UTF8 font installed! 
 
 Usage
 
 
 Link to heading 
 
 
 From STDIN : 
 qrencode -t ansiutf8 <<< 'your_string_here' 
 From file: 
 qrencode -t ansiutf8 < ~/.ssh/id_ed25519.pub

Install git and make in your terraform docker image: 
 # ------------------------------------------------------------------------------ 
 # Packages 
 
 RUN set -exo pipefail && \
 \
 echo 'Installing packages' && \
 apk add --update --no-cache \
 git \
 make 
 Create a Makefile in your terraform directory containing: 
 .PHONY : init
 init : 
…

 Gems
 
 
 Link to heading 
 
 
 Add these to your Gemfile : 
 # Administration 
 gem 'administrate' , '~> 0.20.0' 
 
 # Authentication 
 gem 'devise' , '~> 4.9' , '>= 4.9.3' 
 Then install your new gems: 
 bundle install
 
 Generate
 
 
 Link to heading 
 
 
 bundle exec rails generate devise:install
…

 Gems
 
 
 Link to heading 
 
 
 Add these to your Gemfile : 
 # Administration 
 gem 'activeadmin' , '~> 4.0.0.beta4' 
 
 # Authentication 
 gem 'devise' , '~> 4.9' , '>= 4.9.3' 
 Then install your new gems: 
 bundle install
 
 Generate
 
 
 Link to heading 
 
 
 bundle exec rails generate…

 Prerequisites
 
 
 Link to heading 
 
 
 Install Docker Here . 
 
 Shell
 
 
 Link to heading 
 
 
 You need the bigger Debian based docker image for installing Rails as it needs
to have gcc and make for building naitve extensions. 
 docker-here ruby:3.3.0 bash
 
 Rails
 
 
 Link to heading 
 
 
…
Enable robots.txt in your hugo.toml (formerly config.toml ): 
 enableRobotsTXT = true 
 Add a file layouts/robots.txt with: 
 User-agent: GPTBot
 Disallow: /
 
 User-agent: *
 Allow: /


 Setup
 
 
 Link to heading 
 
 
 Add this to your ~/.bundle/config 
 ---
 
 BUNDLE_GEM__TEST : 'minitest' 
 BUNDLE_GEM__CI : 'gitlab' 
 BUNDLE_GEM__MIT : 'false' 
 BUNDLE_GEM__COC : 'false' 
 BUNDLE_GEM__CHANGELOG : 'false' 
 BUNDLE_GEM__LINTER : 'rubocop' 
 
 Gem Name
 
 
 Link to heading 
 
 
 Use _ for…
Here is how you can make an assertion on a nested call to another class: 
 let( :double ) { instance_double( 'something' ) }
 
 before do 
 allow( SomeClass ) . to receive( :some_method ) . and_return(double)
 allow(double) . to receive( :another ) . and_return( true )
 end 
 
 it 'does something useful' do 
 subject . call
 
 expect( SomeClass ) . to…

 Open your pacman.cfg file: 
 
 sudo vim /etc/pacman.conf
 
 Uncomment or add these instructions: 
 
 Color
ILoveCandy
 
 Update your system with sudo pacman -Syyu . 


 Prerequisites
 
 
 Link to heading 
 
 
 Create a basic file: 
 echo 'abc123' > test123.txt
 
 Digest
 
 
 Link to heading 
 
 
 Find the sha256sum of a file with: 
 sha256sum test123.txt
 You will get the following result: 
 5ecf8d2cc410094e8b82dd0bc178a57f3aa1e80916689beb00fe56148b1b1256 test123.txt
 
 NOTE:…
let result = document. evaluate (
 '/html/body/div/main/div[1]/div[3]/div' ,
 document,
 null ,
 XPathResult . STRING_TYPE ,
 null 
 ) ? . stringValue || '' 
 
 return result 

Put one noop task at the beginning and end of your role: 
 ---
 
 - name : ToolInstall 
 ansible.builtin.meta : noop 
 
 # ... 
 
 - name : ToolInstallEnd 
 ansible.builtin.meta : noop 
 Now you can resume from where you left off with: 
 ansible-playbook playbooks/tool/install.yml --start-at-task = ToolInstall
 And you can skip over that role and…
If you’re tired of seeing these: 
 evil-line-move: Beginning of buffer [81 times]
evil-line-move: End of buffer [32 times]
evil-forward-char: End of line [66 times]
evil-backward-char: Beginning of line [66 times]
 Add these lines to your dotspacemacs/user-config : 
 (with-eval-after-load 'evil 
 (advice-add 'evil-line-move 
 :filter-args
 (lambda (args) (…
Let’s say you have a piece of code: 
 class SomeThing 
 def initialize (thing)
 @thing = thing
 end 
 
 def call 
 puts @thing . inspect
 end 
 end 
 You want to execute this in parallel in a ractor: 
 Ractor . new { SomeThing . new( 1 ) . call }
 This works if you have the block written within the Ractor. But it will fail
if the block is…
If you run git init you will get this yellow hint: 
 hint: Using 'master' as the name for the initial branch. This default branch name
hint: is subject to change. To configure the initial branch name to use in all
hint: of your new repositories, which will suppress this warning, call:
hint:
hint: git config --global init.defaultBranch <name>
hint:
hint: Names commonly…
The best way to structure yout repository is to have an empty root commit and to
squash all the other commits periodically onto the second. This reduces the
repository size making it easier to clone in CI and for your end users. 
 
 Empty root commit
 
 
 Link to heading 
 
 
 Create an empty commit: 
 git commit -m 'Initial commit' --allow-empty
…

 Usage
 
 
 Link to heading 
 
 
 sudo dd \
 bs = 4M status = progress oflag = direct conv = fsync \
 if = /path/to/linux.iso \
 of = /dev/sda
 
 Details
 
 
 Link to heading 
 
 
 
 bs : Buffer size 
 status=progress : shows 3749707776 bytes (3.7 GB, 3.5 GiB) copied, 913 s, 4.1 MB/s 
 oflag=direct : actually…

 Steps
 
 
 Link to heading 
 
 
 Fetch a command with either: 
 
 C-e C-u : go to end of line, cut until beginning of line. 
 C-a C-k : go to start of line, cut until end of line. 
 
 Navigate to older command with: 
 
 C-p : previous command. 
 C-r : search command (use fzf for better
results). 
 
 Navigate to the end with…
You should always check if the value is present in a list before adding it in. 
 function prepend_path () { 
 case ': ${ PATH } :' in
 *: ' $1 ' :* ) 
 ;;
 * ) 
 PATH = ' $1 : ${ PATH } ' 
 esac 
 } 
 
 Usage
 
 
 Link to heading 
 
 
 prepend_path ~/.local/bin
 
 Cleanup
 
 
 Link to heading 
 
 
…

 
 



 

 
 Bash 
 
 echo $PATH | sed 's/:/\n/g' 
 
 






 Docker
 
 
 Link to heading 
 
 
 The best way to manage ruby for your project is by using Docker: 
 
 Docker Images: basic Ruby setup 
 Docker Projects 
 
 If you don’t have a Docker setup yet, you have to suffer, temporarily, by using
 rbenv . There used to be another tool called rvm for this sort of thing but
it’s been…
The instructions at https://brew.sh/ are extremely dangerous! Here is how to
install homebrew properly. 
 
 NOTE: we assume your homebrew path is: ~/Workspace/Hub/brew 
 
 Code
 
 
 Link to heading 
 
 
 
 
 Clone the repository: 
 git clone https://github.com/Homebrew/brew.git ~/Workspace/Hub/brew
 
 cd ~/Workspace/Hub/brew
…

 Setup
 
 
 Link to heading 
 
 
 Your .gitignore : 
 *.elc
 A Makefile containing: 
 .PHONY : compile
 compile : 
 	@emacs -q -batch \
 	 --eval '(setq byte-compile-error-on-warn t)' \
 	 -f batch-byte-compile \
 	 *.el
 
 The first indentation is a tab, the following two are spaces. Makefiles just
work this…

 Package
 
 
 Link to heading 
 
 
 Find the location of your diff-highlight package: 





 
 
 



 

 
 Manjaro/Arch 
 
 pacman -Ql git | grep diff-highlight
 
 




 



 

 
 Debian/Ubuntu 
 
 dpkg -L git | grep diff-highlight
…

 Install
 
 
 Link to heading 
 
 
 From package: 
 # Manjaro / Arch 
 sudo pacman -S ansible-lint
 
 # Alpine 
 apk add --update ansible-lint
 From Docker (no official image so use mine): 
 docker run --rm -it -v ' $PWD ' :/work -w /work sdwolfz/ansible-lint:latest sh
 
 Configure
 
 
 Link to heading 
 
 
…

 Basic
 
 
 Link to heading 
 
 
 sudo echo 'blacklist pcspkr' > /etc/modprobe.d/nobeep.conf
 And restart your machine! 
 
 Automated
 
 
 Link to heading 
 
 
 Add this to an ansible role roles/os/configure/nobeep.yml : 
 # ------------------------------------------------------------------------------- 
 # Bell Sound 
 #…

 HTML
 
 
 Link to heading 
 
 
 < div class = 'tabs tab-right' >
 < style >
 . tabs input #tab1: checked ~ . tab-content-1 , 
 . tabs input #tab2: checked ~ . tab-content-2 , 
 . tabs input #tab3: checked ~ . tab-content-3 {
 display : block ;
 }
 </ style >
 
 < input type = 'radio' name = 'tab-select' id = 'tab1' checked />
 <…
The command is: 
 git diff --exit-code
 Prints the diff and exits with status code 1 . 
 
 CI
 
 
 Link to heading 
 
 
 generate :
 image : ruby:3.1.2-alpine 
 script :
 - apk add --update git make 
 - make generate 
 - git diff --exit-code 

Are you a hardcore elisp programmer? Add this to your ~/.spacemacs : 
 dotspacemacs-additional-packages ' (
 (treemacs :location
 (recipe :fetcher file
 :path '~/path/to/treemacs/src/elisp' )
 :update nil ))
 Now you can hack on any emacs package in your live editor! 
 
 Notes
 
 
 Link to heading 
 
 
 
 You will need to manually delete…

 Install
 
 
 Link to heading 
 
 
 npm init
 npm install --save-dev esbuild
 
 Setup
 
 
 Link to heading 
 
 
 Add this to your esbuild.js file: 
 const esbuild = require ( 'esbuild' )
 
 const targets = [ 'chrome58' , 'firefox57' , 'safari11' ]
 
 esbuild . build ({
 entryPoints : [ 'src/main.js' ],
…

 Tips
 
 
 Link to heading 
 
 
 Disable garbage collection when benchmarking for more accurate results. 
 GC . disable
 
 # ------------------------------------------------------------------------------ 
 # Code goes here 
 
 # ------------------------------------------------------------------------------ 
 
 GC . enable
 
…

 Prerequisite
 
 
 Link to heading 
 
 
 
 Ruby Minitest and Simplecov starter 
 
 
 Usage
 
 
 Link to heading 
 
 
 # Create a mock 
 mock = Minitest :: Mock . new
 
 # Add expectations. 
 # 
 # Arguments: 
 # 1. Method name 
 # 2. What to return when called 
 # 3. Expected inputs 
 mock .…

 Setup
 
 
 Link to heading 
 
 
 Use the basic, standard, bundled, ruby HTTP library, no other gem needed. 
 require 'net/http' 
 
 url = 'https://www.codrut.pro' 
 headers = { 'X-HELLO' => 'world' }
 use_ssl = true 
 
 GET
 
 
 Link to heading 
 
 
 params = { 'a' => 1 }
 result = nil 
 
 uri = URI…
Locations: 
 # System 
 /usr/share/applications/
 /usr/local/share/applications/
 
 # Flatpak 
 /var/lib/flatpak/exports/share/applications/
 
 # Snap 
 /var/lib/snapd/desktop/applications/
 
 # Local 
 ~/.local/share/applications/
 Search for your application in those directories and edit the files, using
 root privileges where necessary.…

 History
 
 
 Link to heading 
 
 
 View history: 
 journalctl -b
 Tail history: 
 journalctl -b -f
 
 Cleanup
 
 
 Link to heading 
 
 
 sudo journalctl --vacuum-size = 100M

You have the following: 
 callable = proc { puts 'Hello' }
 Pass it to a function like this: 
 def pass_me_something 
 yield if block_given?
 end 
 
 pass_me_something( & callable)
 Or be explicit: 
 def pass_me_something ( & block)
 block . call if block_given?
 end 
 
 pass_me_something( & callable)
 You can also be weird: 
 def…
One argument: 
 (defmacro macro-evaluates-arg (arg)
 'Evaluate `ARG' .' 
 ` (when (not ( null arg))
 , arg))
 Multiple arguments: 
 (defmacro macro-evaluates-args ( &rest args)
 'Evaluate `ARGS' .' 
 ` (when (not ( null args))
 ,@ args))


 Rules
 
 
 Link to heading 
 
 
 Here are my rules for git branch names: 
 
 Don’t start with the letter m , that’s reserved for master or main . 
 No prefixes! 
 No ids inside branch names. 
 Use english words, more than one… 
 Pick either - or _ for separator, but be consistent, never mix. 
 Use common sense! 
…
JavaScript developers have no dignity! Here is how you can restore it: 
 npm config set fund false
 
 Docker
 
 
 Link to heading 
 
 
 Add this to your Dockerfile : 
 # ------------------------------------------------------------------------------ 
 # NPM 
 
 RUN set -ex && \
 \
 echo 'Restore dignity to the jacascript community' &&…

 Install
 
 
 Link to heading 
 
 
 sudo pacman -S openbsd-netcat
 
 Use
 
 
 Link to heading 
 
 
 With an IP: 
 nc -v 127.0.0.1 5432 
 Or a URL: 
 nc -v www.codrut.pro 443 

netstat -atun
 Now either grep or browse to see if you accidentally exposed your database to
the world.
Useful for all sorts of things: 
 while true; do echo 'Inside the loop' ; sleep 5; done 

Setup package.json by running: 
 npm init -y
 Add packages: 
 npm install --save-dev \
 @babel/core \
 @babel/preset-env \
 babel-loader \
 webpack \
 webpack-cli
 Create webpack.config.js with index.js as your main, and bundle.js as
output: 
 const webpack = require ( 'webpack' );
 const path = require ( 'path' );
 
 const config = {
…

 Read
 
 
 Link to heading 
 
 
 file = CSV . open( 'path/to/file.csv' , col_sep : ',' )
 file . each do | line | 
 pp line
 end 
 
 Write
 
 
 Link to heading 
 
 
 header = [ 'A' , 'B' , 'C' ] 
 content = [[ 1 , 2 , 3 ] , [ 4 , 5 , 6 ]] 
 
 csv = CSV . generate do | output | 
 output << header
 
…
Every image or document you create has built in spyware, remove it like this: 
 
 Install
 
 
 Link to heading 
 
 
 sudo pacman -S perl-image-exiftool
 
 Usage
 
 
 Link to heading 
 
 
 exiftool -overwrite_original_in_place -all = path-to-file


 Prerequisites
 
 
 Link to heading 
 
 
 sudo pacman -S gimp imagemagick poppler
 
 PDF to PNG
 
 
 Link to heading 
 
 
 Create a directory with your INITAIL.pdf then execute this inside of it: 
 pdftoppm INITIAL.pdf prefix-for-images -png
 
 Do whatever
 
 
 Link to heading 
 
 
 Edit your images in…

 Prerequisites
 
 
 Link to heading 
 
 
 Make sure you have systemd installed with at least version 248 : 
 pacman -Ss systemd | grep 'core/systemd ' 
 
 # core/systemd 248.2-1.1 [installed] 
 
 Setup
 
 
 Link to heading 
 
 
 Check if the service is active: 
 systemctl status systemd-oomd.service
 Enable and start…

 
 Navigate to your function. 
 
 
 Instrument it with C-u M-x eval-defun , or C-u , e f in Spacemacs. 
 
 
 Execute that function. 
 
 
 Debug with these shortcuts: 
 
 
 
 Key 
 Action 
 
 
 
 
 s 
 Next sexp. 
 
 
 i 
 Step in. 
 
 
 o 
 Step out. 
 
 
 d 
…
find . -type f -exec sed -i 's/STRING GOES HERE/REPLACEMENT HERE/g' {} +
 Make sure to escape brackets ( \[\] ): 
 find . -type f -exec sed -i 's|Click \[here\](/here/)!|Click HERE!|g' {} +