Pursuing the question of, whether a Linux subsystem, that runs under Android, due to the UserLAnd app, can be used for Web development.

It was a subject which I wrote about several months, or years ago, that I had installed the “UserLAnd” app on my Google Pixel C Tablet, so that I could install Debian Linux on it. And a question which one reader had asked me was, whether such an arrangement could be used, to carry out Web development. In fact, some question existed, as to whether proprietary software could be made to run, and my answer was, that it would be preferred to run only Free, Open-Source Software.

In the meantime, I’ve uninstalled Linux from the Pixel C, and installed it on my Samsung Galaxy Tab S6, which has 256GB of internal storage, so that this question can be examined more seriously.

The answer I’d give to this question is, that Web-development can be done in this way, as long as the developer accepts some severe restrictions.

  • Successful development of any kind will depend on whether the user has a real keyboard to type on.
  • The Open-Source application “Bluefish” runs out-of-the box, which is more than I can say for any sort of Python IDE.
  • Because there is little possibility to run a Web-server on the tablet, the features which Bluefish would normally have, to edit PHP Scripts as well, will simply need to be ignored. The ability to preview the Web-pages written, depends on the Guest System’s Firefox browser following the ‘prooted’ Guest System’s Filename-Paths, so that, when Bluefish opens Firefox, the HTML File will essentially be opened as if from the hard drive. And the feature works…

 

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The main reason I would say, not to invest in paid-for software on this platform, is, because its full potential will not be realized.

The HTML and CSS Files created in this way will next need to be transferred to an actual Web-server, and some of the ways in which Bluefish would be set up on a real Linux box, would make this easier.

 

(Updated 10/03/2020, 4h00: )

Continue reading Pursuing the question of, whether a Linux subsystem, that runs under Android, due to the UserLAnd app, can be used for Web development.

Revisiting the Android, UserLAnd app.

One of the facts which I had reported some time ago was, that a handy, easy-to-use Android app exists, which is called ‘UserLAnd‘, and, that I had installed it on my Google Pixel C Tablet. As the tooltip suggests, this is an Android app that will allow people to install a basic Linux system, without requiring ‘root’. Therefore, it mounts the apparent, local Linux file system with ‘proot’ – which is similar in how it works to ‘chroot’, except that ‘proot’ does not require root by the host system to set up – and any attempts to obtain root within this Linux system really fail to change the userid, of the app that the files belong to, or of the processes running. Yet, becoming root within this sandboxed version of Linux will convince Linux, for the purpose of installing or removing packages via ‘apt-get’.

In the meantime, I have uninstalled the ‘UserLAnd’ Linux guest system from my Pixel C Tablet, in order to free up storage. But, I have set up something like this again, on my Samsung Galaxy Tab S6 Tablet, which has 256GB of internal storage. Therefore, I have a few observations to add, about how this app runs under Android 10.

Through no fault of the developer of this Android app, the user is more restricted in what he can run, because Android 10 places new restrictions on regular processes. Specifically, none of the major LISP Interpreters that were designed to run under Debian 10 / Buster will run. (:1) What the Linux developers did was, to make the garbage collection of their LISP Interpreters more aggressive, through a strategy that changes the memory protection bits of memory-maps, to read-only if they belong to the state of the machine, and then, ~to try deleting as much of the bytecode as can still be deleted~. Pardon me, if my oversimplification gets some of it wrong.

Well, Android 10 no longer allows regular apps to change the protected memory state of any pages of RAM, for which reason none of the affected LISP Interpreters will run. And for that reason, neither “Maxima” nor anything that depends on Maxima can be made to run.

Yet, certain other Linux applications, notably “LibreOffice” and “Inkscape”, run just fine… So does “GIMP”…

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Also, the way in which files can be shared between theĀ  Android Host and the Linux Guest System has been changed, as the following two screen-shots show:

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Here, the file ‘Text-File.txt’ has been shared between Android and Linux. Larger files can also be shared in the same way, and the folder bookmarked under Linux. (:2)

In many ways, the Linux applications behave as described before, with the unfortunate exceptions I just named, and I intend to keep using this app.

Technically, a Host app that just sandboxes a Guest Application in this way, does not count as a Virtual Machine. A real VM allows processes to obtain root within the Guest System, without endangering the Host System. Also, ‘a real VM’ provides binary emulation, that makes no specific assumptions about the Guest System, other than, usually, what CPU is being used. Emulation that includes non-native CPU emulation is still a somewhat special type of emulation.

Therefore, the ability of Debian 10 / Buster to run under ‘UserLAnd’ depends, in this case, on the Linux package maintainers having cross-compiled the packages, to run on an ‘ARM-64′ CPU…

 

(Updated 9/13/2020, 21h30… )

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A 3rd-party, Android email client, still worth using: FairEmail.

One of the observations which I’ve made about the Android platform is, that many of the 3rd-party email apps that once used to run well, no longer do so under Android 10, and that, additionally, their devs have often abandoned them.

For that reason, I’m happy to find that such an app still exists, or newly exists, and its name is FairEmail. This is an app, the free version of which can actually be used in the long term, but which I paid for, just to get the extra features.

One of the observations which I can make about this app is, that it has a plethora of settings, some of which I haven’t learned the meaning of yet. But, by default, the way to use it is to follow what is located in its first settings tab, which displays wizards to set up email accounts according to a database of recognized providers, and then, to leave the settings at their defaults. Additional wizards help the user give the app special settings under Android. The app directs the user to the required or optional settings, but it’s up to the user actually ‘to throw the switch’ each time. (:2)

Multiple email accounts can all be set up, using the same wizard.

The app runs in phone-optimized as well as tablet-optimized formats.

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One of the features that were highly important to me was, support for both ‘S/MIME’ and ‘OpenPGP’. When using OpenGPG, this app will always encode it using the trendy ‘PGP/MIME’ format, and no longer, using ‘Clearsigning’, which was also referred to as ‘Inline Format’. The use of OpenPGP requires that an additional key-management app be installed, and on my devices, Open Keychain was already so, and was recognized immediately by FairEmail.

The app displays many widgets inside displayed emails, most of which give explicit commands to do things, that might impact the privacy of the user, such as, to display images, to display tracking images, etc. The app tries to distinguish between these two types of images because additionally, being an IMAP Client, downloading even plain images will consume additional data, when many emails can Humanly be understood, without the need actually to see the images. This is especially true for actual Spam.

The app leaves Spam filtering up to the IMAP Server, but displays the Spam Folder as fully accessible.

And many configuration details show me, that it assumes trendy preferences, even though I can’t say that either I, or most of my email contacts, qualify as trendy Internet users. One trendy feature is that this app mainly supports IMAP, and that any support of POP3 which the user may find, will be incomplete at best.

Another trendy setting in this app has to do with “Flowed Text”. This is a term which refers to ‘Pure Text Emails’, in which one paragraph is essentially written on one line. Traditionally, this lack of formatting was reserved for HTML-composed emails, and the receiving email client would always display those flowed. By contrast, traditionally, Pure Text had fixed line-lengths, determined by the sender, and the receiving client would break lines where line-breaks were sent, even if doing so, or not doing so, tended to wreck the appearance of the email…

(Updated 8/13/2020, 10h10… )

Continue reading A 3rd-party, Android email client, still worth using: FairEmail.

Another possible reason, why my Google Pixel C might have started crashing.

One of the facts which I posted about recently was, that My Google Pixel C Tablet had started crashing, roughly every one or two months. Because I haven’t really installed any new software on it, and because the most recent System Update took place sometime in mid-2019, I had assumed that the recent malfunctions could be due to some sort of hardware problem.

The fact that this tablet, which I only bought in 2017, was starting to become unstable, was partially also, why I have recently acquired a Samsung Galaxy Tab S6 tablet, as an eventual replacement.

But, there is in fact another possible explanation, for the crashes of the Pixel C. Until 2019, that tablet had received System Updates roughly once every month. It might just be that, due to many memory leaks, that tablet really needs to be rebooted once per month, and if nothing else, System Updates also resulted in soft reboots. The failure to perform any soft reboots, may be what’s leading to hard reboots. Only, hard reboots are dangerous, because too many of them can lead to file system corruption.

In that regard, I’m hoping that the new Tab S6, which has Android 10 installed, will offer a possible preventive measure, in the fact that it can be scheduled in advance, to reboot automatically, let’s say once per week. If that feature works out as expected, then the tablet in question may indeed last longer than the Pixel C did.

Really, I think it strange, that an Android tablet would crash – or hard-boot – because it was not soft-booted for more than a month. After all, my phones, also being Android devices, have usually been able to run for more than 2 months, without requiring any reboots, and when those finally do receive a soft-boot, it’s part of their System Update.

Dirk