Category Archives: Server Operations

View the TLS Certificate Details of a Website on the Command Line Using GnuTLS

Last updated on December 27, 2023

With GnuTLS, we can view the certificate details of a website with the following commands (replace "example.com" with the website of your interest):

gnutls-cli --print-cert example.com < /dev/null | certtool --certificate-info

In the command above, gnutls-cli --print-cert example.com < /dev/null prints the certificate of the website in PEM format to the standard output. Its output is then sent as the standard input to certtool --certificate-info, which prints information on the given certificate.

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Nikola: How to Deploy Compiled Webpages to a Different Git Repository

Last updated on November 18, 2018

Nikola is one of the most popular static website generators. It compiles source files into final publishable webpages offline and then uploads those files to a web host. Compared to dynamic websites such as those powered by PHP or Ruby on Rails, static websites offer better security and faster page loading.

Nikola provides some utilities to ease the deployment procedure (i.e., uploading compiled webpages), especially for deploying as GitHub pages. Unfortunately, Nikola does not (and its team does not plan to) provide a direct way to deploy the compiled webpages to a git repository that is different from the one that hosts the source files. This is often useful when you want to hide the source files in a private git repository and leave the git repository that hosts the compiled webpages public. Luckily, Nikola provides customizable deploying commands. Assuming output is the directory where the compiled webpages are located, change the value of DEPLOY_COMMANDS using the following in conf.py (replace me@example.com with your email address, https://xuhdev@github.com/xuhdev/xuhdev.github.io.git with your designated git repository on GitHub/GitLab/BitBucket/etc., and master with your designated branch):

DEPLOY_COMMANDS = {
    'default': [
        "cd output && git init && git config user.email me@example.com && touch .nojekyll && git add .",
        "cd output && git commit -a -m 'Nikola'",
        "cd output && git push -f https://xuhdev@github.com/xuhdev/xuhdev.github.io.git master",
    ]
}

Now running nikola deploy should deploy the compiled webpages to your designated git repository and branch.

Set up Synapse (Matrix Homeserver) on Ubuntu 20.04/16.04

Last updated on May 5, 2021

Matrix is an open standard for decentralized persistent communication, shares somewhat similar goals to Jabber/XMPP. It attracts people from using centralized communicating software such as Facebook Messenger, WhatsApp, etc. In the Matrix protocol, a piece of software called "homeserver" plays a key role to connect users. To use Matrix, one such server must be set up. In this post, we will set up Synapse, an implementation of the Matrix homeserver maintained by the Matrix team, using a minimal configuration on Ubuntu 16.04/20.04.

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Install PHP Extensions on Shared Hosts

Last updated on November 22, 2018

In this post, I will show you a workaround to install additional PHP extensions which are not available on your Linux/BSD shared host. Before you proceed, you should ask whether your shared hosting company has an official way to install or whether they can include the extension you need on their system, as this method is really only a workaround: it probably works, but there is no guarantee of stability, especially your shared hosting company upgrades PHP version.

I’ll assume you have the basic knowledge of how to use a UNIX shell.

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