Wordpress

This grep statement filters out the DB_NAME, DB_USER, DB_PASSWORD and DB_HOST contents from a wp-config.php:

grep -oP "define\(['\"]DB_NAME['\"],\s*['\"]\K[^'\"]+(?=[\'\"]\s*\)\s*;)" wp-config.php

For example, from the wp-config.php line

define('DB_NAME', 'techoverflow');

it will extract techoverflow.

Here are the statements for DB_NAME, DB_USER, DB_PASSWORD and DB_HOST:

DB_NAME=$(grep -oP "define\(['\"]DB_NAME['\"],\s*['\"]\K[^'\"]+(?=[\'\"]\s*\)\s*;)" wp-config.php)
DB_USER=$(grep -oP "define\(['\"]DB_USER['\"],\s*['\"]\K[^'\"]+(?=[\'\"]\s*\)\s*;)" wp-config.php)
DB_PASSWORD=$(grep -oP "define\(['\"]DB_PASSWORD['\"],\s*['\"]\K[^'\"]+(?=[\'\"]\s*\)\s*;)" wp-config.php)
DB_HOST=$(grep -oP "define\(['\"]DB_HOST['\"],\s*['\"]\K[^'\"]+(?=[\'\"]\s*\)\s*;)" wp-config.php)

You can use this, for example, in automatic backup scripts without manually copying the password to the backup script

 Problem:

Your WordPress installation running on Ubuntu 20.04 shows you this error message:

OTGS Installer, responsible for receiving automated updates for WPML and Toolset, requires the following PHP component(s) in order to function:cURL

Learn more: Minimum WPML requirements

Solution:

You need to install the curl package for your PHP version.

Typically you can use

sudo apt -y install php7.4-curl

Doing this should immediately fix the issue (just reload your WordPress dashboard). In case you’re using PHP 7.2 you need to sudo apt -y install php7.2-curl instead.

In case the issue is still not fixed after doing this, try restarting your webserver (e.g. sudo service apache restart or sudo service nginx restart), try restarting PHP-FPM by using sudo service php7.4-fpm restart or sudo service php7.2-fpm restart or try rebooting your server. In case that doesn’t help either, you need to manually check which PHP instance the wordpress site is using and install the curl package for that PHP instance.

WordPress uses dashicons as its primary icon font. However, many themes do not require dashicons on the frontend and hence it’s only used in the admin frontend, i.e. when a user is logged in.

I made a simple plugin to make WordPress load the dashicons CSS only if the user is logged in. For non-logged-in users, the dashicons CSS is removed from the frontend (hence improving the loading speed of your website).

<?php 
/*
Plugin Name: TechOverflow remove dashicons
*/

/**
 * Remove dashicons CSS from the page, only load if user is logged in
 */
function dashicons_admin_only() {
    if(!is_user_logged_in()) {
        global $wp_styles;
        wp_dequeue_style('dashicons');
        // wp_deregister_style('dashicons') causes internal PHP errors in WordPress !
        $wp_styles->registered['dashicons']->src = '';
    }
}
    
add_action( 'wp_print_styles', 'dashicons_admin_only' );

Just create an new folder called techoverflow-no-dashicons inside your wp-content/plugins directory, and save the source code listed above as wp-content/plugins/techoverflow-no-dashicons/functions.php inside. After that, you can modify the code to fit your specific needs.

Note that using this plugin might make your site appear differently if you are logged in. Hence it’s important to check your site when not logged in, e.g. using incognito mode.

Many WordPress plugins provide you with an option to configure whether scripts are loaded in the header or the footer of the page.

If you want to move a script to the footer for performance reasons, and the plugin doesn’t support it, one option is to just edit the wp_enqueue_script() call in the plugin’s source code and set $in_footer = true.

However, these change won’t survive plugin updates and hence are not recommended for security reasons.

A better option is to write a custom plugin that removes the <script> tag from the head and moves it to the footer. The following file is the functions.php of my custom plugin that moves the <script> tag from the cookie-law-info plugin to the bottom of the page.

<?php 
/*
Plugin Name: TechOverflow Cookie Law to footer
*/

function postpone_script($name) {
    global $wp_scripts;
    // Get attributes from original script
    $thesrc = $wp_scripts->registered[$name]->src;
    $theversion = $wp_scripts->registered[$name]->ver;
    // Remove script from the header
    wp_dequeue_script($name);
    wp_deregister_script($name);
    // Add script to the bottom
    wp_enqueue_script($name, $thesrc, false /* no deps */, $theversion, true /* bottom */);
}

/**
 * Move cookie law javascript to the bottom
 */
function postpone_cookie_law() {
    postpone_script('cookie-law-info');
}
    
add_action( 'wp_print_scripts', 'postpone_cookie_law' );

Just create an new folder called techoverflow-cookie-law-footer inside your wp-content/plugins directory, and save the source code listed above as wp-content/plugins/techoverflow-cookie-law-footer/functions.php inside. After that, you can modify the code to fit your specific needs.

Remember to check your page for issues (javascript errors, delayed rendering of some elements) that appear when you move the javascript to the footer, since some plugins may not be compatible with the script being placed in the footer. Also, you might need to call postpone_script() multiple scripts with different $name argument. Check the original plugin’s wp_enqueue_script() calls for the correct $name (first argument). In case it’s not obvious which wp_enqueue_script() call relates to a specific script, you can also check the version in the src of the original <script> tag (e.g. 1.8.2 in ...?ver=1.8.2 ) and search for that version in the plugin’s folder to find the matching wp_enqueue_script() call.

Use this snippet in your wordpress plugin to load a script only if a user is logged in:

function enqueue_my_script() {
    if(is_user_logged_in()) {
        wp_enqueue_script( 'my-script', plugins_url('/my-script.js', __FILE__), false, '1.0', 'all');
    }
}

add_action( 'wp_enqueue_scripts', 'enqueue_my_script');

It does not matter how exactly you use wp_enqueue_script(), just wrap it in a

if(is_user_logged_in()) {
    // Call wp_enqueue_script() here !
}

Also see:
Minimal WordPress CSS plugin example
Minimal WordPress Shortcode plugin example

This plugin adds a static Javascript .js file to WordPress which is loaded in the client.

First, create a directory for your plugin in wp-content/plugins/, e.g. wp-content/plugins/my-js-plugin

Save the following code as functions.php in the plugin folder, e.g. wp-content/plugins/my-js-plugin/functions.php

<?php
/*
Plugin Name: My JS plugin
*/

function my_plugin_enqueue_js(){
    wp_enqueue_script('my-plugin-js', plugins_url('/script.js', __FILE__), false, '1.0.0', true /* in footer */);
}
add_action('wp_enqueue_scripts', "my_plugin_enqueue_js");

Next, save your desired JS file in script.js in the plugin folder, e.g. wp-content/plugins/my-js-plugin/script.js. Example script:

jQuery(document).ready(function() {
    console.info("Your JS plugin works!");
});

Now activate your plugin your WordPress admin area.

Your Javascript will be loaded on each WordPress page until you deactivate the plugin.

Note that if you are using a JS-optimizing plugin like Autoptimize, you might not actually see your JS file as separately loaded script file as it is compiled into the single Autoptimize JS. You javascript will still be loaded on the client!

Also see:
Minimal WordPress JS plugin example
Minimal WordPress Shortcode plugin example

This plugin adds a static CSS file to WordPress.

First, create a directory for your plugin in wp-content/plugins/, e.g. wp-content/plugins/my-css-plugin

Save the following code as functions.php in the plugin folder, e.g. wp-content/plugins/my-css-plugin/functions.php

<?php
/*
Plugin Name: My CSS plugin
*/

function my_plugin_enqueue_css(){
    wp_enqueue_style('my-plugin-stylesheet', plugins_url('/style.css', __FILE__), false, '1.0.0', 'all');
}
add_action('wp_enqueue_scripts', "my_plugin_enqueue_css");

Next, save your desired CSS file in style.css in the plugin folder, e.g. wp-content/plugins/my-css-plugin/style.css. Example for a stylesheet:

/* This is just an example CSS and does not have any specific meaning! */
.my-plugin-class {
    font-weight: bold;
}

Now activate your plugin your WordPress admin area.

Your CSS will be loaded for each WordPress page until you deactivate the plugin.

Note that if you are using a CSS-optimizing plugin like Autoptimize, you might not actually see your CSS file as separately loaded stylesheet as it is compiled into the single Autoptimize CSS. You style will still be loaded!

Also see:
Minimal WordPress JS plugin example
Minimal WordPress CSS plugin example

This plugin creates a simple (static – no parameters) shortcode in WordPress

First, create a directory for your plugin in wp-content/plugins/, e.g. wp-content/plugins/my-shortcode-plugin

Save the following code as functions.php in the plugin folder, e.g. wp-content/plugins/my-shortcode-plugin/functions.php

<?php 
/*
Plugin Name: My shortcode plugin
*/

function my_shortcode( $atts , $content = null ) {
   return '<h2>Shortcode works</h2>';
}
 
add_shortcode( 'my-shortcode', 'my_shortcode' );

Now activate your plugin your WordPress admin area.

You can now create a post or page containing this code:

[my-shortcode][/my-shortcode]

which will be rendered like this:

Shortcode works

Also see:
Minimal WordPress JS plugin example
Minimal WordPress CSS plugin example
Minimal WordPress Shortcode plugin example

This is the minimal wordpress plugin – it does not do anything at all, but you can activate it and use it as a basis for your plugins.

First, create a directory for your plugin in wp-content/plugins/, e.g. wp-content/plugins/my-plugin

Save the following code as functions.php in the plugin folder, e.g. wp-content/plugins/my-plugin/functions.php

<?php 
/*
Plugin Name: My plugin
*/

Now you can activate your plugin your WordPress admin area: