Solution

1. 1. Remove the symbolic link of privkey.pem under

      /etc/letsencrypt/live/[mydomain]/privkey.pem

   2. recreate the symbolic link with the dedicated user running Jupyter notebook.
   3. Run command as root:

      systemctl restart jupyterhub

Tricks

1. 1. • As the jupyter server is run by the ownership of a dedicated user, after the renewal, the private key, i.e. privkey.pem must be owned by this user. However, I run the command:

        certbot renew --standalone

        under root.

      • note that let’s encrypt command for CentOS 6 is quite different from CentOS7

Config

1. • OS: CentOS 7
   • Jupyter-notebook: 5.7.8

The post SSL Key Ownership appeared first on LarryLai.

Default ordered list item style is decimal number, lower/upper alpha, lower/upper roman then followed by a dot. Thought it’s easy to change the dot to something like
  a) This is good 1st item
  b) This is good 2nd item.

      instead of:
  a. This is not good 1st item
  b. This is not good 2nd item

However, there’s no simple way to change the style of ordered list item and remove the dot after the order number <ol> <li></li></ol>.
As I got used to markdown’s convinence of auto numbering for ordered list items, don’t want to hard code the order into the list.

Solution

1. Removing the default ordering number and using counter by creating counter variable (say, list) like this
     ol { list-style-type: none; counter-reset: list;}
2. Update counter variable for each \
3. like this `ol>li { counter-increment: list; }
4. Display the content of the new counter like this `ol>li::before { content: counter(list, lower-alpha) ") "; }

Tricks

• It’s a bit complex for multi-level ordered list, but the principle still applies
• Some more has to be added to see hanging text like default ordered list display. This can be done by the following for modifying 2nd order level :

  ol ol {    
    list-style-type: none;    
    counter-reset: list;   
  }     
  ol ol>li::before {     
    content: counter(list, lower-alpha) ") \00a0";
    display: inline-block;
    width: 1.5em;
    text-align: right;
  }    
  ol ol>li {    
    counter-increment: list;    
    margin-left: .5em;    
    text-indent: -1.5em;    
  } 
  

  Of course, several paramenters can be adjusted to fit into each individual case. These include margin-left, text-indent spaces and the counter number style, i.e. lower-alpha, lower-roman, decimal, etc.

The post CSS List item style a) b) appeared first on LarryLai.

Solution

• In the setting of the plugin, choose the tab Additional Firewall Rules
• Uncheck the option at the bottom, i.e. Advanced Character String Filter

Config

• WordPress 5.3
• All In One WP Security v4.4.2
• MathJax-LaTex v1.3.11

The post MathJax Load Failed – WP Security Plugin appeared first on LarryLai.

VirtualBox client CentOS can’t boot up with error message:

1. [FAILED] Failed to start Virtual Machine and Container Registration Service.
2. [FAILED] Failed to start Login Service.
   

Solution

Disable SELINUX config with the following steps during boot up sequence:

1. During Grub boot up stage, press 'e' to edit grub sequence;
2. Add systemd.unit=rescue.target to the end of line with linux16 and boot with rescue mode;
3. Press ctrl+x to continue boot sequence

Config

• CentOS 7 3.10
• VirtualBox 6.0.10

Tricks

• The cause of this boot up issue was difficult to found and the original setting of SELINUX was ‘permissive’ not ‘enabled’. However, this issue may also be owing to bugs in VirtualBox 6.
• During boot up process, by default the boot up is quiet, i.e. no system message will be displayed, only the boot up progress bar is seen. However, pressing Esc key will let you see the detail boot up messages.

The post CentOS VM Client Can’t Boot Up appeared first on LarryLai.

Solution
Be sure that jupyter-notebook is used instead of jupyter notebook, i.e.
ExecStart=/[pathOfTheBinary]/jupyter-notebook
or else it should be bracketed with quotation marks to ensure the space between jupyter and notebook is allowed.

Tricks

• Be sure that the path of the jupyter binary is correct
• Most of the info. on the web suggesting the content of jupyter.service file missed the fact that jupyter notebook is recommended to be run by non-root user, and it’s imperative that the location of jupyter configuration file must be specified in the jupyter.service file and not just the User=[jupyterUser] directive.

Config

• CentOS: 7-6
• jupyter: Anaconda3-5

The post Jupyter Notebook on Boot Automatically appeared first on LarryLai.

After installing a WordPress plugin – WP Health, it’s reminded that PHP5 had no longer been supported since late 2018, thus there may be risk in all WordPress websites.

Issue

Since removing PHP5 (retrospectively known that it’s not necessary), and installed remi’s repository’s PHP72, some WordPress sites could not be accessed with message: “Internal Server Error. The server encountered an internal error or misconfiguration and was unable to complete your request.” Then using VirtualBox’s snapshot to roll back and finally got every site back to normal.

However, using re-check configuration of Virtualmin to see if there’s anything need to follow up, it’s known that mod_actions of Apache wasn’t enabled. Then after enabling mod_actions by uncommenting the following:

LoadModule actions_module modules/mod_action.so

in /etc/httpd/conf.modules.d/00-base.conf, something weird that instead of executing php page, these pages were downloaded. Some members on forums suggested that the following in /etc/httpd/conf.d/php.conf should be commented out:

SetHandler application/x-httpd-php

This really solved the problem of not executing php pages, but another weird thing happened. Some other websites couldn’t be accessed again with message: 500 Internal Server Error.

Solution

1. The permission of some html directories all granted to 775 and changed owner as apache.
2. In Virtualmin, Server Config -> Website Options -> PHP script execution mode must select FPM if mod_fpm is installed and enable.

Tricks

Before comment out SetHandler application/x-httpd-php, directory permission was not a problem. What and how does something change the permission or why is the permission of html directories should be further granted to eliminated 500 Internal Server Error?

Config

• WordPress 5.1
• Virtualmin 6
• PHP7.2 remi
• CentOS7

The post PHP 7 & Related Issues appeared first on LarryLai.

Background

After installing WP Health, it’s shown that both MariaDB 5 (a default replacement of MySQL for CentOS7) and PHP5.6 are obsolete, i.e. no more formal support and no security patches will be released. It’s suggested to upgrade at least to MariaDB10 and PHP7.

Apart from security and support concern, it’s known that PHP7 has better performance than PHP5.

Issue

After upgrading, either the Virtualmin has problem in displaying submenu on the left panel or there’re “Internal Server Error” on some WordPress sites. It’s found out that during yum update MariaDB, it’s required to remove the old MariaDB5, however, for packages dependency needs, yum will at the same time remove Postfix and Virtualmin-base. If these 2 packages are reinstalled after upgrading to MariaDB, then WordPress has problem.

Solution

Use rpm -e –nodeps to skip removal of Postfix and Virtualmin-base.

Tricks

After removal PHP5.6, list out all the related packages, e.g. php-mysqlnd, php-gd, etc. depending on my case, there’re some others. All these have to be reinstalled after installing PHP7.2 base package.

For upgrade of PHP7, never upgrade to the lastest PHP7.3 as some of the PHP packages do not have PHP7.3 compatible rpm, only have PHP7.2 compatible rpm. There’re many CentOS PHP7 upgrade info. on the web, but some are not good, after try and error, I use TecAdmin.net’s advice and got no problem.

Config

• CentOS: 7.6
• Virtualmin 6.06
• WordPress 5.1
• MariaDB: 10.1

The post Centos7 Virtualmin Upgrade PHP7 MariaDB appeared first on LarryLai.

when launching iTunes, it closed immediately after clicking the icon and appeared in half a second, then error screen appeared to ask for “ignore”, “report”, etc.

Solution:

1. Finder -> Applications -> iTunes.app
2. right click -> Get Info
3. Expand “Sharing & Permissions”
4. click bottom right lock icon and input admin password
5. select system permissions
6. click bottom wheel icon and select “Make system the owner”
7. install the latest iTunes pkg

Tricks:

• Without step 6 above, no matter how uninstall, remove iTunes.app and reinstall the latest version, it will fail to restore it properly.
• System always complains when simply removing iTunes.app by stating that iTunes is required by MacOS.
• Even login as root in Terminal command, the directory iTunes.app cannot be removed.
• Asking Apple support through discussions.apple.com, people only suggest reinstall the latest version of iTunes but no one suggest checking wheel icon under Sharing & Permissions of Get Info window.

Config:

• MacOS: High Sierra 10.13.2
• iTunes:  12.7.2.60

The post Cannot launch or remove iTunes from Mac High Sierra appeared first on LarryLai.

When open an email box, error appeared on iPhone warning: Cannot verify Mail Server Identity. One solution for this problem is to delete that mail account on iPhone and add it back. However, after account deleted, I could not add it back with the following warning:

Mail Account already exists

Solution:

Logout iCloud on the iPhone

Add the deleted mail accounts

Tricks:

In previous version of iOS, when it showed that the system could not verify the mail server, it was easy to fix by accepting the certificate of the mail server. In my case, the certificate was expired, and I did not want to pay for SSL certificate renewal.

After deleting the mail account, actually it will not be listed on the account list. Thus, there is no clue why the error message was prompted.

Config:

• hardware: iPhone 6S
• iOS:  11.2.1

The post Mail Server Already Exists error iPhone iOS 11 appeared first on LarryLai.

During scanning stage of running the Duplicator plugin on a WordPress site, there was an error: Server Error 500.

Solution:

Modify /etc/php.ini file to increase memory:

memory_limit = 256M

from 128M

Tricks:

Even there is error during the scanning stage, Duplicator still allowed building step to proceed and showing no error.

Error 500 actually does not tell anything informative

No special message was logged in Apache web server

Config:

• PHP               5.6.30
• WordPress     4.7.4
• Duplicator     1.2.4

The post WordPress Duplicator Plugin Server Error 500 appeared first on LarryLai.