Adventures & experiences in contemporary technology
During a recent upgrade from Linux Mint 18 to Linux Mint 18.1 on a secondary machine, I ran into bother with my Startech KVM (keyboard, video, mouse and audio sharing) switch. The PC failed to recognise the attachment of my keyboard and mouse so an internet search began.
Nothing promising came from it apart from resetting the KVM switch. In other words, the solution was to turn it off and back on again. That was something that I did try without success. What I had overlooked was that there USB connections to PC’s that fed the device with a certain amount of power and that was enough to keep it on.
Unplugging those USB cables as well as the power cable was needed to completely switch off the device. That provided the reset that I needed and all was well again. Otherwise, I would have been baffled enough to resort to buying a replacement KVM switch so the extra information avoided a purchase that could have cost in the region of £100. In other words, a little research had saved me money.
Because updating Piwik using its web interface has proved tempestuous, I have decided update the self-hosted analytics application an ssh session. The production web servers that I use are hosted on Linux systems so that is why any commands apply to the Linux or UNIX command line only. What is needed for Windows servers may differ.
The first step is to down the required ZIP file with this command:
wget https://builds.piwik.org/piwik.zip
Once the download is complete, the contents of the ZIP archive are extracted into a new subfolder. This is a process that I carry out in a separate folder to that where the website files are kept before copying everything from the extract folder in there. Here is the unzip command and the -o switch turns on overwriting of any previously existing files:
unzip -o piwik.zip
Without the requirement folder in web server area updated, the next step is to do the actual system update that includes any updates to the Piwik database that you are using. There are two commands that you can use once you have specified the location of your Piwik installation. The second is needed when the first option cannot find where the PHP executable is stored. My systems had something more specific than these because both PHP 5.6 and PHP 7.0 are installed. Looking in /usr/bin was enough to find what i needed to execute in place of php below. Otherwise, the command was the same.
./[path to piwik]/console core:update
php [path to piwik]/console core:update
While the upgrade is ongoing, it prompts you to permit it to continue before it goes and makes changes to the database. This did not take long on my systems but that depends on how much data there is. Once, the process has completed, you can delete any extraneous files using the rm command.
My usual method for copying a directory tree without any of the files in there involves the use of the Windows commands line XCOPY and the command takes the following form:
xcopy /t /e <source> <destination>
The /t switch tells XCOPY to copy only the directory structure while the /e one tells it to include empty directories too. Substituting /s for /e would ensure that only non-empty directories are copied. <source> and <destination> are the directory paths that you want to use and need to be enclosed in quotes if you have a space in a directory name.
There is one drawback to this approach that I have discovered. When you have long directory paths, messages about there being insufficient memory are issued and the command fails. The limitation has nothing to do with the machine that you are using but is a limitation of XCOPY itself.
After discovering that, I got to checking if ROBOCOPY can do the same thing without the same file path length limitation because I did not have the liberty of shortening folder names to get the whole path within the length expected by XCOPY. The following is the form of the command that I found did what I needed:
robocopy <source> <destination> /e /xf *.* /r:0 /w:0 /fft
Again, <source> and <destination> are the directory paths that you want to use and need to be enclosed in quotes if you have a space in a directory name. The /e switch copies all subdirectories and not just non-empty ones. Then, the xf *.* portion excludes all files from the copying process. The remaining options are added to help with getting around access issues and to try copy only those directories that do not exist in the destination location. The /ftt switch was added to address the latter by causing ROBOCOPY to assume FAT file times. To get around the folder permission delays, the /r:0 switch was added to stop any operation being retried with /w:0 setting wait times to 0 seconds. All this was enough to achieve what I wanted and I am keeping it on file for my future reference as well as sharing it with you.
In recent months, I have been doing a clear out of paper books in case the recent European Union referendum result in the U.K. affects my ability to stay there since I am an Irish citizen. In my two decades here, I have not felt as much uncertainty and lack of belonging as I do now. It is as if life wants to become difficult for a while.
What made the clearance easier was that there was of making sure that the books were re-used and eBooks replaced anything that I would wanted to keep. However, what I had not realised is that demand for eBooks has flatlined, something that only became apparent in recent article in PC Pro article penned by Stuart Turton. He had all sorts of suggestions about how to liven up the medium but I have some of my own.
Niall Benvie also broached the subject from the point of view of photographic display in an article for Outdoor Photography because most are looking at photos on their smartphones and that often reduces the quality of what they see. Having a partiality to photo books, it remains the one class of books that I am more likely to have in paper form, even I have an Apple iPad Pro (the original 12.9 inch version) and am using it to write these very words. There also is the six year old 24 inch Iiyama screen that I use with my home PC.
The two apps with which I have had experience are Google Play Books and Amazon Kindle, both of which I have used on both iOS and Android while I use the Windows app for the latter too. Both apps are simple and work effectively until you end up with something of a collection. Then, shortcomings become apparent.
Search functionality is something that can be hidden away on menus and that is why I missed it for so long. For example, Amazon’s Kindle supports puts the search box in a prominent place on iOS but hides the same function in menus on its Android or Windows incarnations. Google Play Books consistently does the latter from what I have seen and it would do no harm to have a search box on the library screen since menus and touchscreen devices do not mix as well. The ability to search within a book is similarly afflicted so this also needs moving to a more prominent place and is really handy for guidebooks or other more technical textbooks.
The ability to organise a collection appears to be another missed opportunity. The closest that I have seen so far are the Cloud and Device screens on Amazon’s Kindle app but even this is not ideal. Having the ability to select some books as favourites would help as would hiding others from the library screen would be an improvement. Having the ability to re-sell unwanted eBooks would be another worthwhile addition because you do just that with paper books.
When I started on this piece, I reached the conclusion the eBooks too closely mimicked libraries of paper books. Now, I am not so sure. It appears to me that the format is failing to take full advantage of its digital form and that might have been what Turton was trying to evoke but the examples that he used did not appeal to me. Also, we could do with more organisation functionality in apps and the ability to resell could be another opportunity. Instead, we appear to be getting digital libraries and there are times when a personal collection is best.
All the while, paper books are being packaged in ever more attractive ways and there always will be some that look better in paper form than in digital formats and that still applies to those with glossy appealing photos. Paper books almost feel like gift items these days and you cannot fault the ability to browse them by flicking through the pages with your hands.
BASH is a command-line interpretor that is commonly used by Linux and UNIX operating systems. Chances are that you will find find yourself in a BASH session if you start up a terminal emulator in many of these though there are others like KSH and SSH too.
BASH comes with its own configuration files and one of these is located in your own home directory, .bashrc. Among other things, it can become a place to store command shortcuts or aliases. Here is an example:
alias us=’sudo apt-get update && sudo apt-get upgrade’
Such a definition needs there to be no spaces around the equals sign and the actual command to be declared in single quotes. Doing anything other than this will not work as I have found. Also, there are times when you want to update or add one of these and use it without shutting down a terminal emulator and restarting it.
To reload the .bashrc file to use the updates contained in there, one of the following commands can be issued:
source ~/.bashrc
. ~/.bashrc
Both will read the file and execute its contents so you get those updates made available so you can continue what you are doing. There appears to be a tendency for this kind of thing in the world of Linux and UNIX because it also applies to remounting drives after a change to /etc/fstab and restarting system services like Apache, MySQL or Nginx. The command for the former is below:
sudo mount -a
Often, the means for applying the sorts of in-situ changes that you make are simple ones too and anything that avoids system reboots has to be good since you have less work interruptions.
At the time of writing, Google Drive is unable to accept DNG files, the Adobe file type for RAW images from digital cameras. The uploads themselves work fine but the additional processing at the end that I believe is needed for Google Photos appears to be failing. Because of this, I thought of other possibilities like uploading them to Dropbox or enclosing them in ZIP archives instead; of these, it is the first that I have been doing and with nothing but success so far. Another idea is to convert the files into an image format that Google Drive can handle and TIFF came to mind because it keeps all the detail from the original image. In contrast, JPEG files lose some information because of the nature of the compression.
Handily, a one line command does the conversion for all files in a directory once you have all the required software installed:
find -type f | grep -i “DNG” | parallel mogrify -format tiff {}
The find and grep commands are standard with the first getting you a list of all the files in the current directory and sending (piping) these to the grep command so the list only retains the names of all DNG files. The last part uses two commands for which I found installation was needed on my Linux Mint machine. The parallel package is the first of these and distributes the heavy workload across all the cores in your processor and this command will add it to your system:
sudo apt-get install parallel
The mogrify command is part of the ImageMagick suite along with others like convert and this is how you add that to your system:
sudo apt-get install imagemagick
In the command at the top, the parallel command works through all the files in the list provided to it and feeds them to mogrify for conversion. Without the use of parallel, the basic command is like this:
mogrify -format tiff *.DNG
In both cases, the -format switch specifies the output file type with tiff triggering the creation of TIFF files. The *.DNG portion itself captures all DNG files in a directory but {} does this in the main command at the top of this post. If you wanted JPEG ones, you would replace tiff with jpg. Shoudl you ever need them, a full list of what file types are supported is produced using the identify command (also part of ImageMagick) as follows:
identify -list format
During my days at work, I often hear about the need to restart a server because something has gone awry with it. This makes me wonder if you can kill processes from the command line like you do in Linux and UNIX. A recent need to reset Windows Update on a Windows 10 machine gave me enough reason to answer the question.
Because I already knew the names of the services, I had no need to look at the Services tab in the Task Manager like you otherwise would. Then, it was a matter of opening up a command line session with Administrator privileges and issuing a command like the following (replacing [service name] with the name of the service):
sc queryex [service name]
From the output of the above command, you can find the process identifier, or PID. With that information, you can execute a command like the following in the same command line session (replacing [PID] with the actual numeric value of the PID):
taskkill /f /pid [PID]
After the above, the process no longer exists and the service can be restarted. With any system, you need to find the service that is stuck in order to kill it but that would be the subject of another posting. What I have not got to testing is whether these work in PowerShell since I used them with the legacy command line instead. Along with processes belonging to software applications (think Word, Excel, Firefox, etc.), that may be something else to try should the occasion arise.
In the world of UNIX and Linux, symbolic links are shortcuts but they do not work like normal Windows shortcuts because you do not jump from one location to another with the file manager’s address bar changing what it shows. Instead, it is as if you see the contents of the directory at another quicker to access location in the file system and the same sort of thinking applies to files too. In some ways, it is like giving files and directories alternative aliases. There are soft links that point to the name of a given directory or file and hard links that point to actual files or directories.
For a long time, I was under the mistaken impression that such things did not exist in Windows until I came across the mklink command, which came with the launch of Windows Vista at the start of 2007. While the then new feature may not be an obvious to most of us, it does does that Windows did incorporate a feature from UNIX and Linux well before the advent of virtual desktops on Windows 10.
By default, the aforementioned command sets up symbolic links to files and the /D switch allows the same to be done for directories too. The /H switch makes a hard link instead of a soft link so we get much of the functionality of the ln command in UNIX and Linux. Here is an example that creates a soft symbolic link for a directory:
mklink /D shortcut target_directory
Above, shortcut is the name of the symbolic link file and target_directory is the destination to which it links. In my experience, it works best for destinations beyond your home folder and, from what I have read, hard links may not be possible across different disks either.
On Friday, I was working on a system where a session is instantiated from a stored virtual machine that produces a fresh session every time so all previous changes get lost. What I have is a batch script that I run to reinstate what I need and I encountered another task that I wanted it to do.
Part of my work involves the creation of plain text files with the extension lst and this is getting associated with SAS instead of Notepad. While you can reassign such associations using the GUI, it would be nice to do it via the command line too so the assoc and ftype commands caught my interest. The first of these associates a file with a given extension with a desired file type while the second shows the available file types together with the associated applications that open them. The assoc command also show all the associations that are in place when it is executed with no parameters and the ftype command does the same for file types.
Once you have picked out a file type with the ftype command, then the assoc can be used like the following:
assoc .lst=txtfile
The above associates an extension with a file type. In the this, .lst files are going to get opened by Notepad because of the txtfile association. Though it did not do what I wanted on Friday due to system lockdown, it is good to know that this is possible and that even the Windows command line supports goodies like these.
Today, I was lured into upgrading my 2012 Google (ASUS) Nexus 7 to the final version of Android 5.0 (also known as Lollipop) by an icon in the device’s top panel. Initially, it felt as it was working OK but a certain sluggish could not be overlooked and there have been complaints about this with some questioning the sense of what Google have done. However, there would have been comments about grandfathering the device if they had not left us have the latest release of Android so there was no victory either way. We humans are fickle creatures and there is an example of exactly that in a well observed double-ended short story by the Irish writer Maura Laverty.
My impressions of how the upgrade had lumbered the tablet had me wondering about replacing the thing with either an Apple iPad Mini 2 or a Google (HTC) Nexus 9 but a much less expensive option came to mind: doing a full factory reset of the device using its recovery mode. That may sound drastic but much of what I had on there was in the cloud anyway so there was nothing to lose. So these are the instructions from Google themselves and I will leave you to use them at your own risk:
Note: If your tablet becomes unresponsive at any point during these steps, you can restart it by holding down the Power button for several seconds.
Once that was completed and the tablet restarted, the set-up routine began and took around an hour to reinstate the various apps that had been lost by the rest. Much of that was down to the time taken for re-installation rather than that taken by the actual downloads themselves over a wired broadband connection. The wait was worth it because the Nexus 7 feels more responsive again. While there times when little lags are noticeable, they are nothing next to the slowdown that I had witnessed before the rest. It might have been a better option than attempting to return to Android 4.4.4 using a factory image, which was another option that I was considering. So long as there is no deterioration in speed, the effort expended to do a reset will have been worthwhile.