Tag Archive PHP

Installing Perl modules using CPAN on Linux Mint 19.2

September 28th, 2019

My online travel photo gallery is a self-coded set of PHP scripts that read data from tables in a MySQL database. These tables are built from input XML files using a Perl script that itself creates and executes an SQL script. The Perl script also does some image processing using GraphicsMagick commands to resize images and to add copyright information and image framing. Because this processed one image at a time in a sequential manner, it was taking several minutes to complete and only partly used the capacity of the PC that I used.

This led me to look at adding parallel processing and that is what brought me to looking at the Parallel::ForkManager Perl module. An alternative approach might have been to add new images in such a way as not to need the full run involving hundreds of image files but that will take more work and I fancied having a look at parallelising things anyway.

If it was not there already, the first act would have been to install build-essential to get access to the cpan command. The following command accomplishes this:

sudo apt-get install build-essential

Once that is there, the cpan command needs running and some questions answered to get things going. The first question to answer is whether you want setup to be as automated as possible and the default answer of yes worked for me. The next question to answer regards the approach that cpan takes when installing modules and I chose sudo here (local::lib is the default value and manual is another option). After this, cpan drops into its own command shell. Here, I issued two more commands to continue the basic setup by updating CPAN.pm to the latest version and adding Bundle::CPAN to optimise the module further:

make install
install Bundle::CPAN

Continuing the last of these may need extra intervention to confirmation the suggested default of exit at one point in its operation and that takes a little time to complete. It is after this that Parallel::ForkManager can be installed using the following command:

install Parallel::ForkManager

That completed quickly and the cpan shell was exited using its exit command. Then, the new module was available in scripting after that. The actual use of this module is something that hope to describe in another post so i am ending this one here and the same process is just as applicable to setting up cpan and adding any other Perl CPAN module.

Adding a new domain or subdomain to an SSL certificate using Certbot

June 11th, 2019

On checking the Site Health page of a WordPress blog, I saw errors that pointed to a problem with its SSL set up. The www subdomain was not included in the site’s certificate and was causing PHP errors as a result though they had no major effect on what visitors saw. Still, it was best to get rid of them so I needed to update the certificate as needed. Execution of a command like the following did the job:

sudo certbot --expand -d existing.com,www.example.com

Using a Let’s Encrypt certificate meant that I could use the certbot command since that already was installed on the server. The --expand and -d switches ensured that the listed domains were added to the certificate to sort out the observed problem. In the above, a dummy domain name is used but this was replaced by the real one to produce the desired effect and make things as they should have been.

Moving a website from shared hosting to a virtual private server

November 24th, 2018

This year has seen some optimisation being applied to my web presences guided by the results of GTMetrix scans. It is was then that I realised how slow things were so server loads were reduced. Anything that slowed response times, such as WordPress plugins, got removed. Matomo usage also was curtailed in favour of Google Analytics while HTML, CSS and JS minification followed. What had not happened was a search for a faster server and another website has been moved onto a virtual private server (VPS) to see how that would go.

Speed was not the only consideration since security was a factor too. After all, a VPS is more locked away from other users that a folder on a shared server. There also is the added sense of control so Let’s Encrypt SSL certificates can be added using the Electronic Frontier Foundation’s Certbot. That avoids the expense of using an SSL certificate provided through my shared hosting provider and a successful transition for my travel website may mean that this one undergoes the same move.

For the VPS, I chose Ubuntu 18.04 as its operating system and it came with the LAMP stack already in place. Have offload development websites, the mix of Apache, MySQL and PHP is more familiar to me than anything using Nginx or Python. It also means that .htaccess files become more useful than they were on my previous Nginx-based platform. Having full access to the operating system by means of SSH helps too and should mean that I have less calls on technical support since I can do more for myself. Any extra tinkering should not affect others either since this type of setup is well known to me and having an offline counterpart means that anything riskier is tried there beforehand.

Naturally, there were niggles to overcome with the move. The first to fix was to make the MySQL instance accept calls from outside the server so that I could migrate data there from elsewhere and I even got my shared hosting setup to start using the new database to see what performance boost it might give. To make all this happen, I first found the location of the relevant my.cnf configuration file using the following command:

find / -name my.cnf

Once I had the right file, I commented out the following line that it contained and restarted the database service afterwards using another command to stop the appearance of any error 111 messages:

bind-address 127.0.0.1
service mysql restart

After that, things worked as required and I moved onto another matter: uploading the requisite files. That meant installing an FTP server so I chose proftpd since I knew that well from previous tinkering. Once that was in place, file transfer commenced.

When that was done, I could do some testing to see if I had an active web server that loaded the website. Along the way, I also instated some Apache modules like mod-rewrite using the a2enmod command, restarting Apache each time I enabled another module.

Then, I discovered that Textpattern needed php-7.2-xml installed so the following command was executed to do this:

apt install php7.2-xml

Then, the following line was uncommented in the correct php.ini configuration file that I found using the same method as that described already for the my.cnf configuration and that was followed by yet another Apache restart:

extension=php_xmlrpc.dll

Addressing the above issues yield enough success for me to change the IP address in my Cloudflare dashboard so it point at the VPS and not the shared server. The changeover happened seamlessly without having to await DNS updates as once would have been the case. It had the added advantage of making both WordPress and Textpattern work fully.

With everything working to my satisfaction, I then followed the instructions on Certbot to set up my new Let’s Encrypt SSL certificate. Aside from a tweak to a configuration file and another Apache restart, the process was more automated than I had expected so I was ready to embark on some fine tuning to embed the new security arrangements. That meant updating .htaccess files and Textpattern has its own so the following addition was needed there:

RewriteCond %{HTTPS} !=on
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

This complemented what was already in the main .htaccess file and WordPress allows you include http(s) in the address it uses so that was another task completed. The general .htaccess only needed the following lines to be added:

RewriteCond %{SERVER_PORT} 80
RewriteRule ^(.*)$ https://www.assortedexplorations.com/$1 [R,L]

What all these achieve is to redirect insecure connections to secure ones for every visitor to the website. After that, internal hyperlinks without https needed updating along with any forms so that a padlock sign could be shown for all pages.

With the main work completed, it was time to sort out a lingering niggle regarding the appearance of an FTP login page every time a WordPress installation or update was requested. The main solution was to make the web server account the owner of the files and directories but the following line was added to wp-config.php as part of the fix even if it probably is not necessary:

define('FS_METHOD', 'direct');

There also was the non-operation of WP Cron and that was addressed using WP-CLI and a script from Bjorn Johansen. To make double sure of its effectiveness, the following was added to wp-config.php to turn off the usual WP-Cron behaviour:

define('DISABLE_WP_CRON', true);

Intriguingly, WP-CLI offers a long list of possible commands that are worth investigating. A few have been examined but more await attention.

Before those, I still need to get my new VPS to send emails. So far, sendmail has been installed, the hostname changed from localhost and the server restarted. More investigations are needed but what I have not is faster that what was there before so the effort has been rewarded already.

Improving a website contact form

April 23rd, 2018

On another website, I have had a contact form but it was missing some functionality. For instance, it stored the input in files on a web server instead of emailing them. That was fixed more easily than expected using the PHP mail function. Even so, it remains useful to survey corresponding documentation on the w3schools website.

The other changes affected the way the form looked to a visitor. There was a reset button and that was removed on finding that such things are out of favour these days. Thinking again, there hardly was any need for it any way.

Newer additions that came with HTML5 had their place too. Including user hints using the placeholder attribute should add some user friendliness although I have avoided experimenting with browser-powered input validation for now. Use of the required attribute has its uses for tell a visitor that they have forgotten something but I need to check how that is handled in CSS more thoroughly before I go with that since there are new :required, :optional, :valid and :invalid pseudoclasses that can be used to help.

It seems that there is much more to learn about setting up forms since I last checked. This is perhaps a hint that a few books need reading as part of catching with how things are done these days. There also is something new to learn.

Trying out a new way to upgrade Linux Mint in situ while going from 17.3 to 18.1

March 19th, 2017

There was a time when the only recommended way to upgrade Linux Mint from one version to another was to do a fresh installation with back-ups of data and a list of the installed applications created from a special tool.

Even so, it never stopped me doing my own style of in situ upgrade though some might see that as a risky option. More often than not, that actually worked without causing major problems in a time when Linux Mint releases were more tightly tied to Ubuntu’s own six-monthly cycle.

In recent years, Linux Mint’s releases have kept in line with Ubuntu’s Long Term Support (LTS) editions instead. That means that any major change comes only every two years with minor releases in between those. The latter are delivered through Linux Mint’s Update Manager so the process is a simple one to implement. Still, upgrades are not forced on you so it is left to your discretion as to when you need to upgrade since all main and interim versions get the same extended level of support. In fact, the recommendation is not to upgrade at all unless something is broken on your own installation.

For a number of reasons, I stuck with that advice by sticking on my main machine with Linux Mint 17.3 instead of upgrading to Linux Mint 18. The fact that I broke things on another machine using an older method of upgrading provided even more encouragement.

However, I subsequently discovered another means of upgrading between major versions of Linux Mint that had some endorsement from the project. There still are warnings about testing a live DVD version of Linux Mint on your PC first and backing up your data beforehand. Another task is ensuring that you are upgraded from a fully up to data Linux Mint 17.3 installation.

When you are ready, you can install mintupgrade using the following command:

sudo apt-get install mintupgrade

When that is installed, there is a sequence of tasks that you need to do. The first of these is to simulate an upgrade to test for the appearance of untoward messages and resolve them. Repeating any checking until all is well gets a recommendation. The command is as follows:

mintupgrade check

Once you are happy that the system is ready, the next step is to download the updated packages so they are on your machine ahead of their installation. Only then should you begin the upgrade process. The two commands that you need to execute are below:

mintupgrade download
mintupgrade upgrade

Once these have completed, you can restart your system. In my case the whole process worked well with only my PHP installation needing attention. A clash between different versions of the scripting interpretor was addressed by removing the older one since PHP 7 is best kept for sake of testing. Beyond that, a reinstallation of VMware Player and the move from version 18 to version 18.1, there hardly was anything more to do and there was next to no real disruption. That is just as well since I depend heavily on my main PC these days. The backup option of a full installation would have left me clearing up things for a few days afterwards since I use a bespoke selection of software.