Enlarging a VirtualBox VDI virtual disk
20th December 2018It is remarkable how the Windows folder manages to grow on your C drive, and one in a Windows 7 installation was the cause of my needing to expand the VirtualBox virtual machine VDI disk on which it was installed. After trying various ways to cut down the size, an enlargement could not be avoided. In all of this, it was handy that I had a recent backup for restoration after any damage.
The same thing meant that I could resort to enlarging the VDI file with more peace of mind than otherwise might have been the case. This needed use of the command line once the VM was shut down. The form of the command that I used was the following:
VBoxManage modifyhd <filepath/filename>.vdi --resize 102400
It appears that this also would work on a Windows host, but mine was Linux, and it did what I needed. The next step was to attach it to an Ubuntu VM and use GParted to expand the main partition to fill the newly available space. That does not mean that it takes up 100 GiB on my system just yet because these things can be left to grow over time and there is a way to shrink them too if you ever need to do just that. As ever, having a backup made before any such operation may have its uses if anything goes awry.
Moving a website from shared hosting to a virtual private server
24th November 2018This year has seen some optimisation being applied to my web presences, guided by the results of GTMetrix scans. It 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. Usage of Matomo also was curtailed in favour of Google Analytics, while HTML, CSS and JS minification followed. Something that had yet to happen was a search for a faster server. Now, 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 than 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 using SSH helps too and should mean that I have fewer 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 yielded enough success for me to change the IP address in my Cloudflare dashboard so it pointed 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 to 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 than what was there before, so the effort has been rewarded already.
Using NOT IN operator type functionality in SAS Macro
9th November 2018For as long as I have been programming with SAS, there has been the ability to test if a variable does or does not have one value from a list of values in data step IF clauses or WHERE clauses in both data step and most if not all procedures. It was only within the last decade that its Macro language got similar functionality, with one caveat that I recently uncovered: you cannot have a NOT IN construct. To get that, you need to go about things differently.
In the example below, you see the NOT operator being placed before the IN operator component that is enclosed in parentheses. If this is not done, SAS produces the error messages that caused me to look at SAS Usage Note 31322. Once I followed that approach, I was able to do what I wanted without resorting to older, more long-winded coding practices.
options minoperator;
%macro inop(x);
%if not (&x in (a b c)) %then %do;
%put Value is not included;
%end;
%else %do;
%put Value is included;
%end;
%mend inop;%inop(a);
While running the above code should produce a similar result to another featured on here in another post, the logic is reversed. There are times when such an approach is needed. One is where a few possibilities are to be excluded from a larger number of possibilities. Since programming often involves more inventive thinking, this may be one of those.
Searching file contents using PowerShell
25th October 2018Having made plenty of use of grep on the Linux/UNIX command and findstr on the legacy Windows command line, I wondered if PowerShell could be used to search the contents of files for a text string. Usefully, this turns out to be the case, but I found that the native functionality does not use what I have used before. The form of the command is given below:
Select-String -Path <filename search expression> -Pattern "<search expression>" > <output file>
While you can have the output appear on the screen, it always seems easier to send it to a file for subsequent use, and that is what I am doing above. The input to the -Path switch can be a filename or a wildcard expression, while that to the -Pattern can be a text string enclosed in quotes or a regular expression. Given that it works well once you know what to do, here is an example:
Select-String -Path *.sas -Pattern "proc report" > c:\temp\search.txt
The search.txt file then includes both the file information and the text that has been found for the sake of checking that you have what you want. What you do next is up to you.
Lightening of desktop background images on Linux Mint Debian Edition running in Virtualbox
22nd October 2018After a recent upgrade to Linux Mint Debian Edition 3 in a VirtualBox virtual machine that I had running its predecessor, I began to notice that background images were being loaded with more washed out or faded colours. This happened at startup, so selecting another background image worked as intended until the same thing happened to that after a system restart.
This problem is not new and has affected the Cinnamon desktop in the main Linux Mint variant (the one that is based on Ubuntu) and issuing the following command in a terminal session is a suggested solution:
gsettings set org.cinnamon.muffin background-transition fade-in
In my case, that solved the problem and the desktop background image display is as it should be since I executed the above. All it took was a change to a system setting.
Quickly changing between virtual desktops in Windows 10
12th October 2018One of the benefits of running Linux is the availability of virtual desktops, and installing VirtuaWin was the only way to get the same functionality on Windows before the launch of Windows 10. For reasons known to Microsoft, they decided against the same sort of implementation as seen in Linux or UNIX. Instead, they put the virtual desktop functionality a click away and rather hides it from most users unless they know what clicking on the Task View button allows. The approach also made switching between desktops slower with a mouse. However, there are keyboard shortcuts that address this once multiple virtual desktops exist.
Using WIN + CTRL + LEFT or WIN + CTRL + RIGHT does this easily once you have mastered the action. Depending on your keyboard setup, WIN is the Windows, Super or Command key while CTRL is the Control key. Then, LEFT is the left arrow key and RIGHT is the right arrow key. For machines with smaller screens where multitasking causes clutter, virtual desktops are a godsend for organising how you work, and having quick key combinations for switching between them adds to their utility.
Changing monitor brightness using the Linux command line
11th August 2018Recently, I needed to reduce my monitor brightness but could not make the hardware buttons work. Thus, I considered alternatives and discovered the xrandr command was effective. First, I needed to identify my display name, so I executed the following command with the -q query switch to retrieve this information:
xrandr -q | grep " connected"
The output from this looked like this:
DVI-D-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 521mm x 293mm
My device name appeared as the first block of characters in the above, so I plugged that into the second command below to achieve the desired adjustment.
xrandr --output DVI-D-0 --brightness 0.9
Any value between 0.0 and 1.0 is acceptable, but I went with 0.9 for 90% brightness. The required dimming and brightening then is only a command away.
Updating Flatpack applications on Linux Mint 19
10th August 2018Since upgrading to Linux Mint 19, I have installed some software from Flatpak. The cause for my curiosity was that you could have the latest versions of applications like GIMP or LibreOffice without having to depend on a third-party PPA. Installation is straightforward given the support built into Linux Mint. You just need to download the relevant package from the Flatpak website and run the file through the GUI installer. Because the packages come with extras to ensure cross-compatibility, more disk space is used, but there is no added system overhead beyond that, from what I have seen. Updating should be as easy as running the following single command too:
flatpak update
However, I needed to do a little extra work before this was possible. The first step was to update the configuration file at ~/.local/share/flatpak/repo/config to add the following lines:
[remote "flathub"]
gpg-verify=true
gpg-verify-summary=true
url=https://flathub.org/repo/
xa.title=Flathub
Once that was completed, I ran the following commands to import the required GPG key:
wget https://flathub.org/repo/flathub.gpg
flatpak --user remote-modify --gpg-import=flathub.gpg flathub
With this complete, I was able to run the update process and update any applications as necessary. After that first run, it has been integrated in to my normal processes by adding the command to the relevant alias definition.
Sorting out sluggish start-up and shutdown times in Linux Mint 19
9th August 2018The Linux Mint team never forces users to upgrade to the latest version of their distribution, but curiosity often provides a strong enough impulse for me to do so. When I encounter rough edges, the wisdom of leaving things unchanged becomes apparent. Nevertheless, the process brings learning opportunities, which I am sharing in this post. It also allows me to collect various useful titbits that might help others.
Again, I went with the in-situ upgrade option, though the addition of the Timeshift backup tool means that it is less frowned upon than once would have been the case. It worked well too, apart from slow start-up and shutdown times, so I set about tracking down the causes on the two machines that I have running Linux Mint. As it happens, the cause was different on each machine.
On one PC, it was networking that holding up things. The cause was my specifying a fixed IP address in /etc/network/interfaces instead of using the Network Settings GUI tool. Resetting the configuration file back to its defaults and using the Cinnamon settings interface took away the delays. It was inspecting /var/log/boot.log that highlighted problem, so that is worth checking if I ever encounter slow start times again.
As I mentioned earlier, the second PC had a very different problem, though it also involved a configuration file. What had happened was that /etc/initramfs-tools/conf.d/resume contained the wrong UUID for my system's swap drive, so I was seeing messages like the following:
W: initramfs-tools configuration sets RESUME=UUID=<specified UUID for swap partition>
W: but no matching swap device is available.
I: The initramfs will attempt to resume from <specified file system location>
I: (UUID=<specified UUID for swap partition>)
I: Set the RESUME variable to override this.
Correcting the file and executing the following command resolved the issue by updating the affected initramfs image for all installed kernels and speeded up PC start-up times:
sudo update-initramfs -u -k all
Though it was not a cause of system sluggishness, I also sorted another message that I kept seeing during kernel updates and removals on both machines. This has been there for a while and causes warning messages about my system locale not being recognised. The problem has been described elsewhere as follows: /usr/share/initramfs-tools/hooks/root_locale is expecting to see individual locale directories in /usr/lib/locale, but locale-gen is configured to generate an archive file by default. Issuing the following command sorted that:
sudo locale-gen --purge --no-archive
Following these, my new Linux Mint 19 installations have stabilised with more speedy start-up and shutdown times. That allows me to look at what is on Flathub to see what applications and if they get updated to the latest version on an ongoing basis. That may be a topic for another entry on here, but the applications that I have tried work well so far.
Halting constant disk activity on a WD My Cloud NAS
6th June 2018Recently, I noticed that the disk in my WD My Cloud NAS was active all the time, so it reminded me of another time when this happened. Then, I needed to activate the SSH service on the device and log in as root with the password welc0me. That default password was changed before doing anything else. Since the device runs on Debian Linux, that was a simple case of using the passwd command and following the prompts. One word of caution is in order since only root can be used for SSH connections to a WD My Cloud NAS and any other user that you set up will not have these privileges.
The cause of all the activity was two services: wdmcserverd and wdphotodbmergerd. One way to halt their actions is to stop the services using these commands:
/etc/init.d/wdmcserverd stop
/etc/init.d/wdphotodbmergerd stop
The above act only works until the next system restart, so these command should make for a more persistent disabling of the culprits:
update-rc.d -f wdmcserverd remove
update-rc.d -f wdphotodbmergerd remove
If all else fails, removing executable privileges from the normally executable files that the services need will work, and it is a solution that I have tried successfully between system updates:
cd /etc/init.d
chmod 644 wdmcserverd
reboot
Between all of these, it should be possible to have you WD My Cloud NAS go into power saving mode as it should, even if turning off additional services such as DLNA may be what some need to do. Having turned off these already, I only needed to disable the photo thumbnail services that were the cause of my machine's troubles.