Modify WordPress Admin Panel General Settings Easily

Code

<?php
// Hook into the 'admin_menu' action to add a custom settings section
add_action('admin_menu', 'wp_dudecom_add_custom_settings_section');

function wp_dudecom_add_custom_settings_section() {
    // Add a new section to the General Settings page
    add_settings_section(
        'wp_dudecom_custom_settings_section', // Section ID
        'Custom Settings Section', // Section Title
        'wp_dudecom_custom_settings_section_callback', // Callback function
        'general' // Page to add the section to
    );

    // Register a new setting for the custom field
    register_setting('general', 'wp_dudecom_custom_setting');

    // Add a new field to the custom section
    add_settings_field(
        'wp_dudecom_custom_setting', // Field ID
        'Custom Setting', // Field Title
        'wp_dudecom_custom_setting_callback', // Callback function
        'general', // Page to add the field to
        'wp_dudecom_custom_settings_section' // Section to add the field to
    );
}

// Callback function for the custom settings section
function wp_dudecom_custom_settings_section_callback() {
    echo '<p>Enter your custom settings below:</p>';
}

// Callback function for the custom setting field
function wp_dudecom_custom_setting_callback() {
    // Retrieve the existing value from the database
    $value = get_option('wp_dudecom_custom_setting', '');
    // Output the input field
    echo '<input type="text" id="wp_dudecom_custom_setting" name="wp_dudecom_custom_setting" value="' . esc_attr($value) . '" />';
}
?>