Technology Tales

Clearing the Julia REPL

During development, there are times when you need to clear the Julia REPL. It can become so laden with content that it becomes hard to perform debugging of your code. One way to accomplish this is issuing the CTRL + L keyboard shortcut while focus is within the REPL; you need to click on it first. Another is to issue the following in the REPL itself:

print("\033c")

Here \033 is an escape code in octal format. It is often used in terminal control sequences. The c character is what resets the terminal to its initial state. Printing this sequence is what does the clearance, and variations can be used to clear other kinds of console screens too. That makes it a more generic solution.

Dropping to an underlying shell using the ; character is another possibility. Then, you can use the clear or cls commands as needed; the latter is for Windows systems.

One last option is to define a Julia function for doing this:

function clear_console()
    run(`clear`)  # or `cls` for Windows
end

Calling the clear_console function then clears the screen programmatically, allowing for greater automation. The run function is the one that sends that command in backticks to the underlying shell for execution. Even using that alone should work too.

Mouse configuration in macOS

Now having a new location from which I can work, I acquired an all-in-one desktop computer for use while there. While tempted by an HP option that runs Windows, I ended up choosing an iMac instead. That gained me extra disk space and more memory at a cost. Having UNIX-style command line capability was another attraction. After living with the Windows terminal for a while, its limitations were all too apparent to me.

While I started off desktop computing on a Macintosh Classic and having owned a MacBook Pro in the more recent past, there still was a learning curve. One of these related to the configuration of the mouse supplied with the system. Whatever about only having one button and needing to learn gestures, it was the speed at which the pointer goes that really got me reaching for my more usual Evoluent. Even so, the subsequent discovery of LinearMouse makes things much more bearable once all the requisite permissions were assigned.

Getting the Evoluent configured to my liking needed another third-party application: USB Overdrive. If Evoluent's own software fitted the bill, that would have done. However, they have done some finger pointing at Apple instead of updating it to work with the latest Mac technology. There may be truth in the accusations, but it is striking that another piece of software works when theirs does not. Nevertheless, the other option worked once it got the permissions to detect the hardware. Then, it was a matter of working out which button was which on the mouse, so I could have them assigned as I wished.

After that, I could settle into the new system and get used to its idiosyncrasies. Adding Parallels got me a Windows 11 virtual machine for business compatibility, while I got going with setting up some automation using the macOS terminal. All is becoming more settled than working out of a laptop.

Needing third-party software does have a catch, though: underlying changes to macOS could scupper things. It was the sort of thing that made me move away from GNOME Shell as my Linux desktop. The extensions on which I was depending kept getting obsoleted by every new release. It is something to watch, even if macOS evolves less dramatic than GNOME 3 in its various forms.

Accessing Julia REPL command history

In the BASH shell used on Linux and UNIX, the history command calls up a list of recent commands used and has many uses. There is a .bash_history file in the root of the user folder that logs and provides all this information, so there are times when you need to exclude some commands from there, but that is another story.

The Julia REPL environment works similarly to many operating system command line interfaces, so I wondered if there was a way to recall or refer to the history of commands issued. So far, I have not come across an equivalent to the BASH history command for the REPL itself, but there the command history is retained in a file like .bash_history. The location varies on different operating systems, though. On Linux, it is ~/.julia/logs/repl_history.jl while it is %USERPROFILE%\.julia\logs\repl_history.jl on Windows. While I tend to use scripts that I have written in VSCode rather than entering pieces of code in the REPL, the history retains its uses. Thus, I am sharing it here for others. In the past, the location changed, but these are the ones with Julia 1.8.2, the version that I have at the time of writing.

Expanding the coding toolkit: Adding R and Python in a changing landscape

Over the years, I have taught myself a number of computing languages, with some coming in useful for professional work while others came in handy for website development and maintenance. The collection has grown to include HTML, CSS, XML, Perl, PHP and UNIX Shell Scripting. The ongoing pandemic allowed to me add two more to the repertoire: R and Python.

My interest in these arose from my work as an information professional concerned with standardisation and automation of statistical results delivery. To date, the main focus has been on clinical study data, but ongoing changes in the life sciences sector could mean that I may need to look further afield, so having extra knowledge never hurts. Though I have been a SAS programmer for more than twenty years, its predominance in the clinical research field is not what it was, which causes me to rethink things.

As it happens, I would like to continue working with SAS since it does so much and thoughts of leaving it after me bring sadness. It also helps to know what the alternatives might be and to reject some management hopes about any newcomers, especially regarding the amount of code being produced and the quality of graphs being created. Use cases need to be assessed dispassionately, even when emotions loom behind the scenes.

Since both R and Python bring large scripting ecosystems with active communities, the attraction of their adoption makes a deal of sense. SAS is comparable in the scale of its own ecosystem, though there are considerable differences and the platform is catching up when it comes to Data Science. While the aforementioned open-source languages may have had a head start, it appears that others are not standing still either. It is a time to have wider awareness, and online conference attendance helps with that.

The breadth of what is available for any programming language more than stymies any attempt to create a truly all encompassing starting point, and I have abandoned thoughts of doing anything like that for R. Similarly, I will not even try such a thing for Python. Consequently, this means that my sharing of anything learned will be in the form of discrete postings from time to time, especially given ho easy it is to collect numerous website links for sharing.

The learning has been facilitated by ongoing pandemic restrictions, though things are opening up a little now. The pandemic also has given us public data that can be used for practice, since much can be gained from having one's own project instead of completing exercises from a book. Having an interesting data set with which to work is a must, and COVID-19 data contain a certain self-interest as well, while one remains mindful of the suffering and loss of life that has been happening since the pandemic first took hold.

Restoring the menu bar on GNOME Terminal in a GNOME Shell session

By default, a GNOME Terminal instance does not display a menu bar and that applies not only in GNOME Shell but also on the Cinnamon Desktop environment. In the latter, it is easy enough to display the menu bar using the context menu produced by right-clicking in the window before going to Edit > Preferences and ticking the box for Show menubar by default in new terminals in the General section. After closing the Preferences dialogue, every new GNOME Terminal session will show the menu bar.

Unfortunately, it is not so easy in GNOME Shell, though the context menu route does allow you to unhide the menu bar on a temporary basis. That is because the requisite tick box is missing from the Preferences dialogue box displayed after navigating to Edit > Preferences in the menus. To address, you need to execute the following command in a terminal session:

gsettings set org.gnome.Terminal.Legacy.Settings headerbar false

This change permanently adds the menu bar and includes the previously missing tick box, which is selected when necessary. Although GNOME Shell has a minimalist design in some aspects, making this function difficult to access seems excessive.

More thoughts on Windows 10

Now that I have left Windows 8.x behind me and there are a number of my machines running Windows 10, I have decided to revisit my impressions of the operating system. The first Technical Preview was something that I installed in a virtual machine, and I have been keeping an eye on how things have developed since then and intend to retain a Windows Insider installation to see what might be heading our way as Windows 10 evolves as now expected.

After elaborating on the all important upgrade process earlier, I am now moving onto other topics. While the Start Menu is a big item, there are others, as you will see below.

Start Menu

Let's start with an admission: the prototype Start Menu that we got in the initial Windows 10 Technical Preview was more to my liking. Unpinning all the tiles allowed the menu to collapse back to the sort of width that anyone familiar with Windows 7 would have liked. If there was a setting to expunge all tiles at once and produce this state, I would have been well happy.

It was later that we got to learn that Microsoft was not about to consign the Windows 8 Modern interface entirely to history, as many would have wanted. Some elements remain with us, such as a Start Menu with a mandatory area for tiles and the ability to have it display full screen. Some are live, only for this can be turned off on a tile by tile basis and unneeded ones can be removed altogether. It is even possible to uninstall most apps by right-clicking on a tile or other Start Menu entry and selecting the required option from the resulting context menu. For others, there is a command line alternative that uses PowerShell to do removals. After this pruning, things were left in such a state that I have not been moved to restore Classic Shell so far.

While the Start Menu settings used to be in the same place as those for the taskbar, they are found now in the new Settings tool. Some are in the Personalisation section, and it has its own Start subsection for setting full screen mode or highlighting of new apps, among other things. The equivalent Colours subsection is where you find other settings like assigning background colours based on those in a desktop background image, which itself is assigned in it own subsection in the Personalisation area.

Virtual Desktops

Initially, I failed to see the point in how Microsoft implemented these and favoured VirtuaWin instead. My main complaint was the taskbar showed buttons for all open apps regardless of the screen in which they are opened. However, that was changed, so your taskbar shows different buttons for each virtual desktop, just like the way that Linux and UNIX do things. Switching between desktops may not be as smooth as those yet, but the default setting is a move in the right direction, and you can change it if you like.

Cortana

Though this was presented to the world as a voice operated personal assistant like Apple's Siri, I cannot say that I am keen on such things, so I decided to work as I usually do instead. Keyboard interaction works fine, and I have neutered things to leave off web searches on Bing to use the thing much in the same way as the search box on the Windows 7 Start Menu. While it may be able to do more than that, I am more than happy to keep my workflow unchanged for now. Cortana's settings are available via its pop-up menu. Collapsing the search box to an icon to save space for your pinned and open applications is available from the Search section of the taskbar context menu (right-clicking the taskbar produces this).

Settings

In Windows 8.x, the Control Panel was not the only area for settings but remained feature complete. However, the same is not the case for Windows 10 where the new Settings panel is starting to take over from it. Though the two co-exist for now, it seems clear that Settings is where everything is headed.

Though the Personalisation section of the tool has been mentioned in relation to the Start Menu, there are plenty of others. For instance, the Privacy one is one that definitely needs reviewing, and I found myself changing a lot of the default settings in there. Naturally, there are some other sections in Settings that hardly need any attention from most of us and these include Ease of Access (accessibility), Time & language, Devices and Network & Internet. The System section has a few settings like tablet mode that may need review, while the Update & security one has backup and recovery subsections that may be of interest. The latter of these is where you find the tools for refreshing the state of the system following instability or returning to a previous Windows version (7 or 8.x) within thirty days of the upgrade.

Migrating to Windows 10

While I have had preview builds of Windows 10 in various virtual machines for the most of twelve months, actually upgrading physical and virtual devices that you use for more critical work is a very different matter. Also, Windows 10 is set to be a rolling release with enhancements coming on an occasional basis, so I would like to see what comes before it hits the actual machines that I need to use. That means that a VirtualBox instance of the preview build is being retained to see what happens to that over time.

While some might call it incautious, I have taken the plunge and completely moved from Windows 8.1 to Windows 10. The first machine that I upgraded was more expendable, and success with that encouraged me to move onto others before even including a Windows 7 machine to see how that went. The 30-day restoration period allows an added degree of comfort when doing all this. The list of machines that I upgraded were a VMware VM with 32-bit Windows 8.1 Pro (itself part of a 32-bit upgrade cascade involving Windows 7 Home and Windows 8 Pro), a VirtualBox VM with 64-bit Windows 8.1, a physical PC that dual booted Linux Mint 17.2 and 64-bit Windows 8.1 and an HP Pavilion dm4 laptop (Intel Core i3 with 8 GB RAM and a 1 TB SSHD) with Windows 7.

The main issue that I uncovered with the virtual machines is that the Windows 10 update tool that is downloaded onto Windows 7 and 8.x does not accept the graphics capability on there. This is a bug because the functionality works fine on the Windows Insider builds. The solution was to download the appropriate Windows 10 ISO image for use in the ensuing upgrade. There are 32-bit and 64-bit disk images with Windows 10 and Windows 10 Pro installation files on each. My own actions used both disk images.

During the virtual machine upgrades, most of the applications that considered important were carried over from Windows 8.1 to Windows without a bother. Anyone would expect Microsoft's own software like Word, Excel and others to make the transition, but others like Adobe's Photoshop and Lightroom made it too, as did Mozilla's Firefox, albeit requiring a trip to Settings to set it as the default option for opening web pages. Less well-known desktop applications like Zinio (digital magazines) or Mapyx Quo (maps for cycling, walking and the like) were the same. Classic Shell was an exception but the Windows 10 Start Menu suffices for now anyway. Also, there was a need to reinstate Bitdefender Antivirus Plus using its new Windows 10 compatible installation file. Still, the experience was a big change from the way things used to be in the days when you used to have to reinstall nearly all your software following a Windows upgrade.

The Windows 10 update tool worked well for the Windows 8.1 PC, so no installation disks were needed. Neither was the bootloader overwritten so the Windows option needed selecting from GRUB every time there was a system reboot as part of the installation process, a temporary nuisance that was tolerated since booting into Linux Mint was preserved. Again, no critical software was lost in the process apart from Kaspersky Internet Security, which needed the Windows 10 compatible version installed, much like Bitdefender, or Epson scanning software that I found was easy to reinstall anyway. Usefully, Anquet's Outdoor Map Navigator (again used for working with walking and cycling maps) continued to function properly after the changeover.

For the Windows 7 laptop, it was much the same story, albeit with the upgrade being delivered using Windows Update. Then, the main Windows account could be connected to my Outlook account to get everything tied up with the other machines for the first time. Before the obligatory change of background picture, the browns in the one that I was using were causing interface items to appear in red, not exactly my favourite colour for application menus and the like. Now they are in blue, and all the upheaval surrounding the operating system upgrade had no effect on the Dropbox or Kaspersky installations that I had in place before it all started. If there is any irritation, it is that unpinning of application tiles from the Start Menu or turning off live tiles is not always as instantaneous as I would have liked, and that is all done now anyway.

While writing the above, I could not help thinking that more observations on Windows 10 may follow, but these will do for now. Microsoft had to get this upgrade process right, and it does appear that they have, so credit is due to them for that. So far, I have Windows 10 to be stable and will be seeing how things develop from here, especially when those new features arrive occasionally as is the promise that has been made to us users. Hopefully, that will be as painless as it needs to be to ensure trust is retained.

Initial impressions of Windows 10

Being ever curious on the technology front, the release of the first build of a Technical Preview of Windows 10 was enough to get me having a look at what was on offer. The furore regarding Windows 8.x added to the interest, so I went to the download page to get a 64-bit installation ISO image.

That got installed into a fresh VirtualBox virtual machine and the process worked smoothly to give something not so far removed from Windows 8.1. However, it took until release 4.3.18 of VirtualBox before the Guest additions had caught up with the Windows prototype, so I signed up for the Windows Insider program and got a 64-bit ISO image to install the Enterprise preview of Windows 10 into a VMware virtual machine since and that supported full screen display of the preview while VirtualBox caught up with it.

Of course, the most obvious development was the return of the Start Menu, and it works exactly as expected too. Initially, the apparent lack of an easy way to disable App panels had me going to Classic Shell for an acceptable Start Menu. It was only later that it dawned on me that unpinning these panels would deliver to me the undistracting result that I wanted.

Another feature that attracted my interest is the new virtual desktop functionality. Here I was expecting something like what I have used on Linux and UNIX. There, each workspace is a distinct desktop, with only the applications open in a given workspace showing on a panel in there. Windows does not work that way with all applications visible on the taskbar regardless of what workspace they occupy, which causes clutter. Another deficiency is not having a desktop indicator on the taskbar instead of the Task View button. On Windows 7 and 8.x, I have been a user of VirtuaWin and this still works largely in the way that I expect of it too, except for any application windows that have some persistence associated with them; the Task Manager is an example and I include some security software in the same category too.

Even so, here are some keyboard shortcuts for anyone who wants to take advantage of the Windows 10 virtual desktop feature:

• Create a new desktop: Windows key + Ctrl + D
• Switch to previous desktop: Windows key + Ctrl + Left arrow
• Switch to next desktop: Windows key + Ctrl + Right arrow

Otherwise, stability is excellent for a preview of a version of Windows that is early on its road to final release. An upgrade to a whole new build went smoothly when initiated following a prompt from the operating system itself. All installed applications were retained, and a new taskbar button for notifications made its appearance alongside the existing Action Centre icon. So far, I am unsure what this does and whether the Action Centre button will be replaced in the fullness of time, yet I am happy to await where things go with this.

All is polished up to now, and there is nothing to suggest that Windows 10 will not be to 8.x what 7 was to Vista. The Start Screen has been dispatched after what has proved to be a misadventure for Microsoft. Regardless of what was hyped a few years ago, the PC still is with us; touchscreen devices like tablets are augmenting it instead of replacing it for any tasks involving some sort of creation. If anything, we have seen the PC evolve with laptops perhaps becoming more like the Surface Pro, at least when it comes to hybrid devices. However, we are not as happy to smudge our PC screens quite like those on phones and tablets, so a return to a more keyboard and mouse centred approach for some devices is welcome.

What I have here are just a few observations; there are more elsewhere, including a useful article by Ed Bott on ZDNet. All in all, we are early in the process for Windows 10 and, though it looks favourable so far, I will continue to keep an eye on how it progresses. The need to be less experimental than Windows 8.x is being fulfilled: so far, it certainly is less schizophrenic and should not be a major jump for users of Windows 7.

Automatically enabling your network connection at startup on CentOS 7

CentOS 7's release sparked my curiosity, so I tried it in a VirtualBox virtual machine. It uses GNOME Shell in classic mode, making it feel similar to GNOME 2. One thing to note is that it requires at least VirtualBox version 4.3.14, or the Guest Additions kernel drivers won't compile. This might seem surprising when you learn it uses kernel version 3.10.x and GNOME Shell 3.8.4. Like Debian production releases, CentOS chooses established versions for stability, fitting its enterprise-focused user base. Despite this conservative approach, it still looks good, though trying to change the desktop background froze the machine. Otherwise, most things work well.

However, there are surprises, including one I noticed: network connectivity needed switching on every time the VM started. This occurs with the default installation and has been a known issue since at least CentOS 6. It's not difficult to fix once you know how.

What you need to do is look for the relevant configuration file in /etc/sysconfig/network-scripts/ and update that. Using the ifconfig command, I found that the name of the network interface. Usually, this is something like eth0, but it was enp0s3 in my case, so I had to look for a file named ifcfg-enp0s3 and edit that. The text that is sought is ONBOOT=no and that needs to become ONBOOT=yes for network connections to start automatically. To do something similar from the command line, CentOS had suggested the following:

sed -i -e 's@^ONBOOT="no@ONBOOT="yes@' ifcfg-enp0s3

This uses sed for an inline (and case-insensitive) edit of the file to change 'no' to 'yes' after accessing the /etc/sysconfig/network-scripts/ directory. I edited manually with Gedit, which also works. Note that file editing needs superuser privileges, so switch to root with the su command or use sudo.

Fixing Background Image Display in GNOME Shell 3.10

On upgrading from Ubuntu GNOME 13.10 to Ubuntu GNOME 14.04, a few rough edges were to be noticed. One was the display of my chosen background image: it was garbled. Later, I discovered that there is a maximum width of 2560 px for background images in GNOME Shell these days and that things get messy beyond that.

In my case, the image width was around 6000 px, and I was used to it getting resized in GNOME Shell 3.8 and its predecessors. It appears that the functionality got removed after that though, so the workaround of manual image resizing in the GIMP needed to be employed. Though having big images open in memory creates an additional overhead, not handling them very well at all looks like a bug caused by setting 2560 px as a maximum screen width for the GNOME Shell panel and the complete removal of Nautilus from desktop rendering duties. Let's hope that sense is seen with ever larger screen sizes and resolutions coming our way.

It's the sort of thing that did get me looking at adding on Cinnamon 2.2 for a while before setting background image scaling using the indispensable GNOME Tweak Tool was discovered. LinuxG.net has a useful tutorial on this for anyone with such an adventurous streak in them. For now though, I am OK with my set-up but the GNOME project's focus on minimalism could affect us in other ways, so I can see why Clem Lefebvre started the Cinnamon one primarily for Linux Mint and the desktop environment is appearing elsewhere too. After all, Gedit lost its menu bar in GNOME 3.12 so it's just as well that we have alternatives.

Update 2014-05-06: It appears that the desktop image bug that afflicts GNOME Shell 3.10 got sorted for GNOME Shell 3.12. At least, that is the impression that an Antergos instance in a VirtualBox virtual machine gives me.