Archives de catégorie : CheatSheets

Aides-mémoire informatiques

Installing and configuring Zdkimfilter for courier-mta on Debian Buster (+ djbdns)

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Download package

wget https://www.tana.it/sw/zdkimfilter/zdkimfilter-3.8.tar.gz

Install necessary packages

sudo apt install pkg-config libbsd-dev libssl-dev zlib1g-dev libunistring-dev libidn2-dev libopendbx1-dev

Compile and install

tar xfz zdkimfilter-3.8.tar.gz
cd zdkimfilter-3.8
./configure
make
sudo make install

Configure

Get superpowers :

sudo -i

Generate keys

cd /etc/courier/filters
mkdir keys
chown courier:courier keys
cd keys
/usr/local/bin/zdkimgenkey -s mydomain -d thisdomain.org

Here, the selector mydomain is just a name that I chose different from the real domain thisdomain.org for the purpose of this tutorial. You would normally use something like thisdomain.

chown courier:courier *

Setup the DNS

You have to put the public key that you just generated (the mydomain.txt file) into your DNS. It is provided in a bind-compatible format. Since I use djbdns, I have to transform the entry. I use the site https://andersbrownworth.com/projects/sysadmin/djbdnsRecordBuilder/#domainKeys to do the dirty work :

Just enter what follows p= in the TXT.

Configure

cd ..
mv zdkimfilter.conf.dist zdkimfilter.conf

Add a default domain at the end of the config file. I use thisdomain.org but you can use any domain. It is used when zdkimfilter cannot guess the real domain, that is, when the sender is something like paul (without @somedomain.tld).

It is recommended to also add the following lines :

no_signlen = Y
header_canon_relaxed = Y
body_canon_relaxed = Y
cd keys
ln -s mydomain.private thisdomain.org
filterctl start zdkimfilter

Lancer un script au démarrage

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Pour lancer un script au démarrage du système “proprement” (en utilisant systemd) :

1. créer un script et le placer dans /usr/local/bin.

2. créer un fichier de configuration dans /etc/systemd/system/xxx.service

3. Y placer le contenu suivant :

[Unit]
Description=Bypass Dell fan control
Before=i8kmon.service

[Service]
ExecStart=/usr/local/bin/dell-bios-fan-control enable=1
Type=oneshot
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

4. Lancer systemctl daemon-reload

5. Activer le service avec systemctl enable xxx.service

La doc : https://www.freedesktop.org/software/systemd/man/systemd.unit.html#Before=

Répondeur courier-mta avec maildrop et mailbot

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Il faut d’abord indiquer à courier d’utiliser un autre MDA (Mail Distribution Agent) :

/home/vmail/account/.courier :
|/usr/bin/maildrop .mailfilter

Puis indiquer les règles dans /home/vmail/account/.mailfilter :

cc "!joe@gosane.fr"
cc "| mailbot -A \"From: Account <account@gosane.fr>\" \
-N -c utf8 -T reply \
-s \"I'm on vacation\" \
-t 'vacation.txt' \
/usr/sbin/sendmail -f ''"
to "./Maildir"

Il faudra un fichier vacation.txt dans /home/vmail/account.

Raw SQL in Ruby/Rails

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Everyone seems to discourage the use of raw SQL in Ruby applications and while ActiveRecord seems a good solution for general purpose CRUD operations, we have a strong expertise in SQL and we want to use it as much as possible. Here are the bits we have collected so far on the subject. We are new to Ruby/Rails so these might be obvious for some of you. We primarily write this for ourselves.

We are perfectly aware of the “limitations”. We love PostgreSQL and have no intention of being RDBMS-agnostic. At all.

find_by_sql the way we want it

We want named parameters because, despite the overhead, it’s the cleanest way to pass parameters (we don’t have to preserve a strict order which can lead to problems when enhancing the query, counting the “?”, etc). Also, when we use the same parameter several times in the same query, we don’t have to repeat it.

class ClientsController < ApplicationController

	def index
		@clients = Client.find_by_sql(
			<<-SQL
			SELECT idclient,name,email,contacts
			FROM clients 
			ORDER BY nom
			SQL
			)
	end

	def show
		@client = Client.find_by_sql(["	
			SELECT idclient,name,email,contacts 
			FROM clients 
			WHERE idclient = :idclient", 
			{ :idclient => params[:id] } 
		])[0]
	end

For the show method, we have to grab the first element in the array (thus the [0]at the end.

BorgBackup sur une storagebox Hetzner

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Objectif : automatiser les sauvegardes d’une partie de mon /home

Prérequis

Créer un sous-compte (sub-account) sur l’interface Hetzner. Ici ce sera u123456-sub2.

Une clé SSH spécifique

Créer une clé SSH sans phrase de passe pour que les sauvegardes puissent être entièrement automatiques :

ssh-keygen -f .ssh/id_rsa_hetzner

Pour copier la clé publique sur la storagebox, il faut créer un dossier .ssh

Peut-être que l’on peut faire ça avec scp, comme je ne sais pas faire, j’utilise ncftp:

ncftp -u u123456-sub2 u123456.your-storagebox.de

Créer le dossier .ssh

ncftp / > mkdir .ssh

Maintenant on peut copier la clé publique qu’on vient de créer dans .ssh/authorized_keys

scp -P 23 .ssh/id_rsa_hetzner.pub u123456-sub2@u123456-sub2.your-storagebox.de:.ssh/authorized_keys

Créer le dépôt BorgBackup

On définit quelques variables d’environnement pour ne pas les répéter tout le temps :

export BORG_RSH='ssh -i ~/.ssh/id_rsa_hetzner'

export BORG_PASSPHRASE="top_secret_passphrase"

export BORG_REPO="ssh://u123456-sub2@u123456.your-storagebox.de:23/./borgrepo"

On crée le dépôt (repository) :

borg init -e repokey

Un script pour sauvegarder

…à venir…

TdxSpreadSheet creation and filling via code

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Basic usage and formatting

procedure TForm1.b1Click(Sender: TObject);
Var xls:TdxSpreadSheet;
    sh: TdxSpreadSheetTableView;
begin
  xls:=TdxSpreadSheet.Create(Self);
  Try
    xls.BeginUpdate;
    xls.ClearAll;
    sh:=TdxSpreadSheetTableView(xls.AddSheet('Bénéficiaires'));

    // row,col
    if Cells[1,1]=Nil then
      CreateCell(1,1);
    Cells[Row,Col].AsString:='test';
    sh.cells[1,1].Style.Borders[bLeft].Style:=sscbsDouble;
    sh.cells[1,1].Style.Borders[bRight].Color:=clred;
    sh.Cells[1,1].Style.Brush.BackgroundColor:=clcxLightGray;
    sh.Cells[1,1].Style.AlignHorz:=ssahCenter;
    sh.Cells[1,1].Style.DataFormat.FormatCode:='dd/mm/yyyy';
    sh.Cells[1,1].Style.DataFormat.FormatCode:='# ##0.00';
    sh.Cells[1,1].Style.Font.Style:=[fsBold];

    // Formula
    CreateCell(2,1); // B3
    sh.Cells[2,1].SetText('=SUM(B2:B2)',true);

    xls.EndUpdate;
    xls.SaveToFile('C:\Users\gosane\Desktop\text.xlsx');
  Finally
    xls.Free;
  End;
end;

Helpers

function xlscolname(i:integer):string;
var a,b:integer;
begin
  if i<0 then
    result:='?'
  else if i<26 then
    result:=chr(65+i)
  else begin
    a:=i div 26;
    b:=i mod 26;
    result:=chr(64+a)+chr(65+b);
  end;
end;

Working with TPgDAC (DevArt components for Delphi)

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TPgLoader

interface uses DALoader,PgLoader;

Type TMyForm = Class(TForm)
       // ...
       private
         procedure PgLoader1PutData(Sender: TDALoader);
     End;

{...}

procedure TFxxx.PgLoader1PutData(Sender: TDALoader);
var i:Integer;
begin
  for i:=1 to 10 do
    Sender.PutColumnData('fieldname',i,Value);
end;


procedure TFxxx.Import;
Var pgl:TPgLoader;
begin
  pgl:=TPgLoader.Create(Application);
  Try
    pgl.Connection:=DM.PgConnection1;
    pgl.TableName:='MyTableName';
    pgl.Options.BufferSize:=65536;
    // pgl.OnProgress:=LoaderProgress;
    pgl.OnPutData:=PgLoader1PutData;
    pgl.CreateColumns;
    // Remove primary key from PgLoader
    for I := 0 to pgl.Columns.Count-1 do
      if pgl.Columns[i].Name='idprimarykey' then begin
        pgl.Columns.Delete(i);
        break;
      end;
    pgl.Load;
  Finally
    pgl.Free;
  End;
end;

KDE5 – Hints and tips

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Autostarting applications

Plasma can autostart applications and run scripts on startup and shutdown. To autostart an application, navigate to System Settings > Startup and Shutdown > Autostart and add the program or shell script of your choice. For applications, a .desktop file will be created, for shell scripts, a symlink will be created.

Note:

Programs can be autostarted on login only, whilst shell scripts can also be run on shutdown or even before Plasma itself starts.
Shell scripts will only be run if they are marked executable.

Place Desktop entries (i.e. .desktop files) here:

~/.config/autostart : for starting applications at login.

Place or symlink shell scripts in one of the following directories:

~/.config/plasma-workspace/env : for executing scripts at login before launching Plasma.

~/.config/autostart-scripts : for executing scripts at login.

~/.config/plasma-workspace/shutdown : for executing scripts on shutdown.

Source : https://wiki.archlinux.org/index.php/KDE#Autostarting_applications