Running a community IT room where various people can use the pc's and want to ensure that the system is safe and also that a standard startup is presented. There used to be a guest user ability in earlier versions of Ubuntu but since updating all the hardware to Ubuntu 18.04 we are unable to discover how to set up guest user accounts. Any help would be appreciated. Thanks
Is there any way you could revive Guest Sessions in a future LTS distro?  Guest sessions are good security - they give me just enough power to do what I need to do on a daily basis without risking my system. In short, Guest sessions save me from myself.  I had upgraded from 16.04 to 18.04, gotten a problem I couldn't fix and was all to happy to wipe and rebuild my hard drive and return to 16.04.  I can't be the only one who feels this way.
Bizarre spacing with 4 $\star$s $G$ is the set of all subsets of a set $A$, under the operation of $\triangle\;$: Symmetric Difference of sets.  $A$ has at least two different elements.  I need to check if this is a group, and if it does to show if the group is abelian and/or finite.  Associativity - easy from Symmetric Difference. Identity element - empty group. Inverse element - each element is inverse to itself. Am I right?  abelian? finite? Is "princessship" a real word? Are there any other words which have the same letter 3 times consecutively? If you want to buy a house but you also think value will drop… is there something you can do to alleviate the risk? Disclaimer: yours won't be fiscal advice. People involved will consult a professional before doing anything. This is just to gather some preliminary information.  Situation:   you want to buy a house or a flat, in UK you will get a mortgage in GBP, but you'd pay the down payment in EUR you think that there are fairly high chances that the value of houses in UK and GBP will drop the whole point of this question is actually buying the house/flat, renting is not an option by definition   What can you do to mitigate that risk? I am pretty sure $(B_{t}^{2})$ not Markov because the squared random walk is not.    I guess I can repeat the method since to be Markov it must satisfy the discrete.  Thanks Why am I asked for a credit card number to download a free app? I  want to download free app in my iPod touch device and i have the following doubts.  Kindly resolve me doubts.   when i try to download it asks my credit card security number. since i am trying to download free app , why do i need to provide my credit card security code? Will i be debited for downloading the free app from app store?   I cant able to find any information regarding this on apple.  Please provide me some references about this from apple and please resolve my doubts.  Thanks a lot. I always thought the book was Manifest Destiny but its not. The story that sticks in my head was a human in a cage over a pit? Aliens walk in and discuss how dangerous humans were. He eventually escapes. Man I miss this book. wish I wouldve written down every book I ever read. Ugh Can hard drives fully utilize SATA III? My motherboard currently supports both SATA II and III (3 Gb/s and 6Gb/s respectively), but after reading some online, it seems as though connecting a HDD to the 6 Gb/s is pretty much pointless. If this is the case I'm going to leave my two SATA III ports open for something that can actually use it (which at this point I'm not really sure what can).  This is part of an article I read:     In terms of everything else, we saw basically no difference from the same single drive being plugged into a SATA 6Gb/s or SATA 3Gb/s port. All of this is obviously due to the hard drive not being able to actually take advantage of the 6Gb/s bus.   from . What is the geometric meaning of the determinant of a matrix? I know that "The determinant of a matrix represents the area of ​​a rectangle." Perhaps this phrase is imprecise, but I would like to know something more, please.  Thank you very much. Proving that $\sum_{n=0}^\infty \sum_{k=0}^n \frac{(-1)^n}{(k+1)\times (n-k+1)}$ converges Order of a product of elements in a generic group I'm dealing with the following question: having a group $G$ (of which nothing else is specified, doesn't have to be abelian), prove that $|ab|=|ba|$ for any $a$, $b$. Since $G$ is not abelian I'm not sure what to use here. I was thinking that except the case where $b=a^{-1}$, the order of those would be $lcm(m,n)$ where $m$ and $n$ are the orders of a and b. But looking it up it seems not to be so simple, even if all the info I could find was for abelian groups, so I would like some help with this specific case. Why do I get 'HDIO_GET_IDENTITY failed' message when booting with external usb hard drive? I've installed Ubuntu 11.10 on an external USB (2.0) Hard Drive (/dev/sdb1) but when Ubuntu starts I get a message that says:     ata_id[279]: HDIO_GET_IDENTITY failed for '/dev/sdb': Invalid argument   where I made a mistake? The first HD contains Windows 7 (the official OS of my packard bell notebook). Can we theoretically balance a perfectly symmetrical pencil on its one-atom tip? I was asked by an undergrad student about this question. I think if we were to take away air molecules around the pencil and cool it to absolute zero, that pencil would theoretically balance.  Am I correct?  . "A mice problem" vs. "a mouse problem" Did the verb “fire a weapon” exist before the actual introduction of firearms on battlefields?  More specifically, does it make sense for a creative work to have archers (or whatever ranged weaponry) be told to “fire!”, when the world they live in has not yet seen firearms?  It seems some kind of an anachronism to me, since before firearms, “fire” would never propel any projectile...  I've seen several movies do it; I can't remember them all, but for instance I verified it in The Lord of the Rings trilogy (left), Kingdom of Heaven (top right), and more recently Frozen (bottom right):    The first two do it several times (with Kingdom of Heaven also using it on ballistae, and The Return of the King even having Aragorn ask Legolas to ), whereas firearms never appear on the battlefields they feature (Kingdom of Heaven is set in the 12th century; as for The Lord of the Rings, apart from one occurrence of a witchcraft-ish bomb, it's archery and medieval siege engines all the way).  Frozen may be debatable, happening probably somewhere in the 18th or 19th century, but since we only see swords, spears and the like, it made me flinch to hear crossbowmen use “fire!”.  I've also noticed other movies avoiding this, using “loose!” instead, such as Troy (left) and Gladiator (right):    This makes me think it would be the right thing to say instead... although I'm still wondering why not use “shoot”, which seems simpler to me. I'm trying to install a dual boot (with Window 10) on my new XPS-15 (with a SSD 256Go).  Everything works well (following  until I go on step "Installation type".  Where I can't select "Something else", and I already have the partition table but completely empty. I can't see any existing partition, or add new one. (clickable)  Mainad has a valid height and width, however it isn't shown like subad1/subad2. Which are in essence exactly the same! (just a different background image).  Firebug shows my div as greyed out for some weird reason. Replacing the contents of mainad with just some text doesn't solve the problem (problem isn't related to inner elements)..   What's going on?! :( Producing doc/docx from LaTeX Is there any way to produce doc/docx files from LaTeX? Can I prevent enumeration of usernames on my wordpress site? I can see users at the moment using the WPScan tool. My Windows 7 has suddenly stopped displaying Unicode symbols For some strange reason, my computer suddenly doesn't show certain unicode characters anymore! I have no idea what happened.  Affected applications include Windows Explorer (should be Japanese characters), Google Chrome (should be a heart), and Winamp (should be stars):      Russian, German etc. characters are displayed normally. Chrome also displays Japanese script on websites, but not in the GUI. How can I fix it?     TL;DR: A workaround is to put a shortcut with a Unicode name on the desktop so that explorer.exe is the first process to display a Unicode string after booting.     Update: I have tried to use System Restore to fix it. I needed to go back in time quite a while because the most recent restore points didn't solve it so I used one from the middle of November. After that restore, Unicode symbols were displayed again. Then I updated my system with Windows Update again because those were removed during the restore. After that, the error occurred again! I then did a restore to a point before my new updates, but the error persists, and the old restore point (which I used before) is gone and there are currently no other snapshots of the system. Any suggestions on what to do now?  Update 2: I could find a workaround:      Control Panel → Region and Language → Administration → Change Language for Unicode-incompatible programs to Japanese (Japan).    All mentioned programs display their symbols correctly again. However, I don't consider this a fix because these programs are not usually Unicode-incompatible, and it also leads to some (non-serious) artifacts in some programs. I still welcome an answer that tells me what went wrong here and how to fix the issue.  Update 3: I think I have isolated the particular Windows Update which causes the error. It is . I have installed all other updates except this one, and the error did not occur again.  Update 4: The true origin of this problem was Chrome, see accepted answer. Workaround: put shortcut with Unicode name on desktop so that explorer.exe is the first process to display a Unicode string after booting.