Jorge Saldívar

Author: Jorge Saldivar

  • Refining for microblog

    I’ve recently revamped the website to embrace a more microblog-centric design compared to its previous layout. The navigation has been streamlined to three essential sections: ‘About,’ ‘Blog,’ and ‘Contact.’ The primary aim of this blog is to serve as the main channel for sharing my public thoughts and notes on topics I’m passionate about. While I maintain a presence on a few social media platforms, I don’t use them for content sharing. Instead, all my content is published here.

    Refining for microblog

  • Collateral

    I finally got to watch the movie, Collateral, starring Tom Cruise and Jamie Foxx, and I thoroughly enjoyed it. When describing the film to my son, however, I told him it was like playing a campaign on GTA V.

  • How-to Backup a WordPress Website Using WP-CLI

    Backing up a WordPress website using WP-CLI (WordPress Command Line Interface) involves several steps. Here’s a general guide on how to do it:

    1. Install WP-CLI

    If you haven’t already installed WP-CLI, you’ll need to do so. You can find the installation instructions on the WP-CLI’s official website.

    2. Access Your Server

    You’ll need SSH access to your server. Once you’ve logged in, navigate to the root directory of your WordPress installation.

    3. Backup the Database

    To backup your WordPress database, use the following WP-CLI command:

    wp db export

    This command will create a .sql file in your WordPress directory. This file contains all of your WordPress database information.

    4. Backup WordPress Files

    You also need to backup your WordPress files, including themes, plugins, and uploads. To do this, you can use a command like rsync or tar. For example:

    tar -czvf yoursite_backup.tar.gz /path/to/your/wordpress/directory

    This command will create a compressed archive of your WordPress directory.

    5. Download the Backup

    After creating the backup files on your server, you’ll need to download them to a safe location. You can use an FTP client or a command like scp for this purpose.

    6. Automating the Process

    Optionally, you can write a script to automate the backup process and schedule it to run regularly using a cron job.

    Important Tips

    • Test Your Backup: Always test your backups to ensure they work as expected.
    • Secure Your Backup: Keep your backup files in a secure location to prevent unauthorized access.
    • Regular Backups: Schedule regular backups to minimize the risk of data loss.

    Remember, while WP-CLI is a powerful tool, you should be comfortable with command-line interfaces and have the necessary permissions on your hosting server to perform these actions.

    How-to Backup a WordPress Website Using WP-CLI

  • The principle of least privilege

    The principle of least privilege is a key concept in computer security and information security. It refers to the practice of limiting access rights for users to the bare minimum necessary to perform their job functions. This principle is applied to every part of a system, including systems, processes, users, and programs.

    Here are the key aspects of the principle of least privilege:

    1. Access Control: Users are granted only those permissions they need to complete their tasks. For example, a user who needs to read data from a database does not need permissions to modify it.
    2. Minimizing Risk: By limiting the access rights of users and programs, the potential damage from accidents, errors, or unauthorized use is minimized. This reduces the risk of a security breach.
    3. Segmentation of Privileges: Privileges are often segmented and managed separately. For instance, an administrator might have different levels of access depending on the task, rather than having blanket administrative privileges across the entire system.
    4. Regular Review and Adjustment: Privileges should be regularly reviewed and adjusted based on changes in user roles or system configurations. This ensures that the principle remains effective over time.
    5. Application in Software Development: In software development, this principle means giving a program or process only the permissions it needs to operate, thus limiting the potential impact of a security vulnerability in that program.
    6. Defense in Depth: The principle of least privilege is part of a broader security strategy known as defense in depth, where multiple layers of security controls are deployed to protect information and systems.

    Overall, the principle of least privilege is about granting the minimum level of access necessary, reducing the attack surface, and mitigating the potential impact of security breaches.

    The principle of least privilege

  • Crontab

    Issue:

    How to setup cron jobs in Ubuntu (and Linux)?

    Solution:

    Setting up cron jobs on a Linux system like Ubuntu is a straightforward process. Cron jobs are scheduled tasks that your system runs at specified times or intervals. Here’s how you can set them up:

    Accessing the Cron Table:

    1. Open the Terminal: Launch your terminal application.
    2. Edit Cron Jobs for Your User: To edit the cron jobs for your current user, use the following command: crontab -e This command opens your user’s cron file in the default text editor. If it’s your first time using crontab, it may ask you to select an editor (like nano, vi, etc.).
    3. Add a New Cron Job: In the text editor, you can add a new cron job in the following format: * * * * * command-to-execute This is broken down as:
      • Minute (0 - 59)
      • Hour (0 - 23)
      • Day of the month (1 - 31)
      • Month (1 - 12)
      • Day of the week (0 - 6) (Sunday = 0)
      For example, to run a script every day at 5 AM, you would write: 0 5 * * * /path/to/script.sh Make sure your script (script.sh in this example) is executable. You can make it executable with chmod +x /path/to/script.sh.
    4. Save and Exit: After adding your cron job, save and exit the editor. This will install the new cron job.
    5. Verify Your Cron Jobs: To ensure your cron job is listed, use: crontab -l

    Special Syntax:

    Instead of the asterisks, you can use special strings for common intervals:

    • @reboot: Run once, at startup.
    • @yearly or @annually: Run once a year, “0 0 1 1 *”.
    • @monthly: Run once a month, “0 0 1 * *”.
    • @weekly: Run once a week, “0 0 * * 0”.
    • @daily: Run once a day, “0 0 * * *”.
    • @hourly: Run once an hour, “0 * * * *”.

    Common Examples:

    • Backup Every Day at Midnight:
      0 0 * * * /path/to/backup/script.sh
    • Run a PHP Script Every Hour:
      0 * * * * /usr/bin/php /path/to/your/script.php

    Tips:

    • Environment Variables: Cron jobs run in a minimal environment, so you might need to define environment variables that your task requires.
    • Output Handling: By default, cron sends the output of the job to the user’s mail (local mail, not internet email). You can redirect the output to a file or to /dev/null if you don’t need it.
    • Logging: To log the output of a cron job, redirect the output to a file:
      * * * * * command-to-execute >> /path/to/logfile 2>&1
    • Script Permissions: Ensure that any scripts you’re calling are executable and have the appropriate permissions.

    Cron jobs are particularly useful for automating routine tasks like backups, system updates, or periodic cleanup of temporary files.

    Crontab

  • WordPress: How to manually create a user in the database

    Manually creating a WordPress user in the database involves adding a new entry to the wp_users table and assigning the necessary user capabilities. Here are the steps to do this:

    Please exercise caution when making direct changes to your WordPress database, as incorrect changes can break your site. Make sure to back up your database before proceeding.

    1. Access Your Database:
      Log in to your server or hosting provider’s control panel and access the phpMyAdmin or a similar tool to manage your WordPress database.
    2. Find the wp_users Table:
      In phpMyAdmin, look for your WordPress database on the left-hand side and click to select it. Then, find and click on the wp_users table.
    3. Insert a New User:
      Click the “Insert” or “Add” tab (the exact label may vary depending on your phpMyAdmin version). This will open a form for adding a new row to the wp_users table.
    4. Fill in User Information:
      Fill in the following fields for the new user:
    • user_login: Enter the desired username for the new user.
    • user_pass: Generate a secure password hash. You can use online tools to create password hashes or use WordPress’s built-in wp_hash_password function. Make sure to select the MD5 option when entering the password hash.
    • user_nicename: This can be the same as the user_login.
    • user_email: Enter the email address for the new user.
    • user_registered: Set the registration date in the format “YYYY-MM-DD HH:MM:SS”.
    • display_name: The display name for the user.
    1. Insert the User:
      Click the “Go” or “Insert” button to insert the new user into the wp_users table.
    2. Assign Capabilities:
      To assign capabilities to the user, you’ll need to find the user’s ID in the wp_users table (it’s typically an auto-incremented number) and then add an entry in the wp_usermeta table.
    • Go to the wp_usermeta table.
    • Insert a new row with the following values:
      • user_id: The ID of the new user from the wp_users table.
      • meta_key: Enter wp_capabilities.
      • meta_value: Insert a serialized array with the user’s capabilities. For example, to make the user an administrator, you can use a:1:{s:13:"administrator";b:1;}.
    1. Login to WordPress:
      You should now be able to log in to your WordPress site using the credentials you provided.

    Please be extremely careful when making changes directly to the database, and ensure that you have a backup in case anything goes wrong. It’s recommended to use the WordPress admin interface to create and manage users whenever possible to avoid potential issues.

    WordPress: How to manually create a user in the database

  • Credit Card Testing

    PayPal sandbox testing guide

    The PayPal sandbox is a self-contained, virtual testing environment that simulates the live PayPal production environment. The sandbox provides a shielded space where you can initiate and watch while your apps process PayPal API requests without touching any live PayPal accounts.

    Credit Card Testing

  • iOS 17 is out and a couple of things stick out

    The first thing, the battery life took a hit (hopefully, there’s a fix for this asap). The second is the announcement of the upcoming Journal app. I’m curious if this can be synced to WordPress… hopefully there will be an app for that.

    iOS 17 is out and a couple of things stick out

  • Update WordPress MySQL tables from old domain name to new domain name

    This code is typically used when migrating a WordPress site from one domain to another, ensuring that all references to the old domain are updated to the new domain.

    /*
This SQL code block updates various tables in a WordPress database to replace occurrences of the 'Old_Domain_Name' with the 'New_Domain_Name'. The specific tables being updated are:
- wp_options: Updates the option_value column for rows where the option_name is 'home' or 'siteurl'.
- wp_posts: Updates the post_content column.
- wp_postmeta: Updates the meta_value column.
- wp_usermeta: Updates the meta_value column.
- wp_links: Updates the link_url column.
- wp_comments: Updates the comment_content column.
*/

UPDATE wp_options SET option_value = replace(option_value, 'Old_Domain_Name','New_Domain_Name') WHERE option_name = 'home' OR option_name = 'siteurl';

UPDATE wp_posts SET post_content = replace(post_content, 'Old_Domain_Name','New_Domain_Name');

UPDATE wp_postmeta SET meta_value = replace(meta_value,'Old_Domain_Name','New_Domain_Name');

UPDATE wp_usermeta SET meta_value = replace(meta_value, 'Old_Domain_Name','New_Domain_Name');

UPDATE wp_links SET link_url = replace(link_url, 'Old_Domain_Name','New_Domain_Name');

UPDATE wp_comments SET comment_content = replace(comment_content , 'Old_Domain_Name','New_Domain_Name');
    Update WordPress MySQL tables from old domain name to new domain name

  • Image Tag Cheat Sheet

    Basic Usage

    <img src="path/to/image.jpg" alt="Image description" />

    Attributes

    AttributeDescription
    srcThe path to the image file.
    altThe text to display if the image fails to load.
    widthThe width of the image in pixels.
    heightThe height of the image in pixels.
    titleThe text to display when the user hovers over the image.

    Example

    <img src="path/to/image.jpg" alt="Image description" width="200" height="200" title="Image title" />

    Notes

    • The alt attribute is required for accessibility. It is used by screen readers to describe the image to visually impaired users.
    • The width and height attributes are optional. If you do not specify them, the image will be displayed at its original size.
    • The title attribute is optional. It is used to provide additional information about the image when the user hovers over it.
    Image Tag Cheat Sheet