Raspberry Pi 4 as Routed Wireless Access Point

 Posted on May 8, 2022  • Other languages: Tiếng Việt 



                                         +- RPi -------+
                                     +---+ 192.168.1.2 |          +- Laptop ----+
                                     |   |     WLAN AP +-)))  (((-+ WLAN Client |
                                     |   | 192.168.3.1 |          | 192.168.3.2 |
                                     |   +-------------+          +-------------+
                 +- Router ----+     |
                 | Firewall    |     |   +- PC#1 ------+
(Internet)---WAN-+ DHCP server +-LAN-+---+ 192.168.1.3 |
                 | 192.168.1.1 |     |   +-------------+
                 +-------------+     |
                                     |   +- PC#2 ------+
                                     +---+ 192.168.1.4 |
                                         +-------------+
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raspberrypi 

Get actual elapse time in CPP

 Posted on October 13, 2021  • Other languages: Tiếng Việt 

#include <chrono>

int main() {
	std::chrono::time_point <std::chrono::system_clock, std::chrono::duration<double, std::milli>> then = std::chrono::high_resolution_clock::now();;

	// ... do something ...

	std::chrono::time_point <std::chrono::system_clock, std::chrono::duration<double, std::milli>> now = std::chrono::high_resolution_clock::now();;
	double elapseTimeInMS = (now - then).count();

	return 0;
}

Shorter:

#include <chrono>

using namespace std;

int main() {
	auto then = chrono::high_resolution_clock::now();

	// ... do something ...

	auto now = chrono::high_resolution_clock::now();
	double elapseTimeInMS = chrono::duration<double, milli>(now - then).count();

	return 0;
}
cpp 

Firefox tabs in multiple rows

 Posted on August 9, 2021  • Other languages: Tiếng Việt

  1. Go to about:config, enable config toolkit.legacyUserProfileCustomizations.stylesheets.
  2. Go to about:support > Profile Directory > Open Directory. Firefox profile directory will be openned in new window.
  3. In your profile directory, create folder chrome if not exist.
  4. Go to folder chrome, create file userChrome.css.
  5. Copy content from multi-row_tabs.css into userChrome.css.
  6. Restart Firefox.
firefox  css 

Active Application Launcher on Latte Dock by Super button

 Posted on May 29, 2020  • Other languages: Tiếng Việt

  • Right click on the dock > Layouts > Configure…
  • In Settings window, go to Preferences tab
  • In Actions section > Tick Press ⌘ to activate Application Launcher

Or

  • Open ~/.config/kwinrc, then add:

    ...
[ModifierOnlyShortcuts]
Meta=org.kde.lattedock,/Latte,org.kde.LatteDock,activateLauncherMenu
...

  • Reload KWin:

    $ qdbus org.kde.KWin /KWin reconfigure

    Github QA

kde  latte_dock  shortcut 

Generate GPG key non-interactively

 Posted on January 31, 2020  • Other languages: Tiếng Việt

Put information for gen key in a text file, eg. gpg_gen_key:

Key-Type: 1
Key-Length: 2048
Subkey-Type: 1
Subkey-Length: 2048
Name-Real: My Name
Name-Email: [email protected]
Expire-Date: 0
Passphrase: secretpass

Gen key with above text file:

gpg --batch --gen-key gpg_gen_key
gpg 

NGINX Basic Authentication

 Posted on January 30, 2020  • Other languages: Tiếng Việt

Required package

  • For Debian: apache2-utils.

    sudo apt-get install apache2-utils

  • For Fedora: httpd-tools.

    sudo dnf install httpd-tools

Create password file

Run with -c option if /etc/nginx/.htpasswd does not exist:

sudo htpasswd -c /etc/nginx/.htpasswd user1

If .htpasswd already exists, don’t use -c option or file will be overwritten.
To add more user to password file.

sudo htpasswd /etc/nginx/.htpasswd user2
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nginx