Lately my Ubuntu 16.04 has been asking me to upgrade to a newer version. I wonder: if I upgrade what is going to happen to my data and to the programs I have installed?
What are the different ways I can use to upgrade Ubuntu from one release to another?
Displaying attachments on visual force page I need to display attachments on a visual force page for the Case object.  This is the code I am using. I had it working for awhile, but it somehow broke down. It gets all the attachments, but it will not show the images.   &lt;apex:repeat value="{!Case.attachments}" var="att"&gt;             &lt;apex:panelgrid columns="1"&gt;                 &lt;h1&gt;Image/h1&gt;                 &lt;apex:image url="/servlet/servlet.FileDownload?file={!att.Id}"/&gt;             &lt;/apex:panelgrid&gt; &lt;/apex:repeat&gt; Is there a regular expression to detect a valid regular expression? How do I add a DOM element with jQuery? Why does DNS work the way it does? This is a  about DNS (Domain Name Service).   If my understanding of the DNS system is correct, the .com registry holds a table that maps domains (www.example.com) to DNS servers.   What is the advantage? Why not map directly to an IP address? If the only record that needs to change when I am configuring a DNS server to point to a different IP address, is located at the DNS server, why isn't the process instant? If the only reason for the delay are DNS caches, is it possible to bypass them, so I can see what is happening in real time? How can I launch screensaver with a keyboard shortcut? How to make the Navigation Bar of an UINavigationController display at the bottom? I had recently entered the UK without a visa to be with my partner, from 21 July 2016 until 16 December 2016. I hope to return on the 9th of January. We don't meet the income requirement for a Spouse visa. I recently applied to university, and got in, and was intending to return to the UK on a student visa, but my university did not tell me about maintenance fees and my loan wasn't large enough to cover it all, so my visa would have been denied.  Now, I am hoping to attend university in the next semester, and therefore return to the US to apply for that visa. Do you think that if I try to return to the UK without a visa, I will be turned away?  I won't be working or studying during this time, however, I'm afraid that they'll consider it living in the UK illegally; I don't have a criminal record or anything like that. Mysql resolving 127.0.0.1 to hostname I have two complete sentences; the second is in parentheses, essentially a comment on the first.  Where do I place the periods?  I would use this:     They played opera. (I covered my ears.)   Is this punctuation correct? How do you add tags to blocks so they can only be placed on 1 type of block? Example of a series! Give an example of a convergent series $$\sum_{n=1}^{\infty}a_n$$ such that the series $$\sum_{n=1}^{\infty}a_{3n}$$ is divergent..  I cannot find find any kind of series... I am also be very thankful if you find a divergent series (changing the term convergent)... Why Process Builder doesn't work on Delete Scenario? As most of the time we have to think of requirement to accomplished using out-of-Box feature like e.g process builder which we think of an alternative to trigger, but suppose I have to handle scenario of Delete using Process Builder then there is limitation!(e.g calculation of roll-up on Delete) so I am curious about what is that limitation because of which Delete scenario is not handled in Process Builder. Catalan numbers and triangulation Assume $C_n$ is the number of triangulations of a polygon with $n+2$ sides. Using a combinatorial proof, show that $(4n+2)C_n=(n+2)C_{n+1}$.  I don't even know where to start with this one. I understand the triangulation after doing some googling, but I don't know where to go from here to prove the above using just a combinatorial formula. I am going to Santa Monica for 4 weeks to polish my English in July and would like to volunteer at the Planetary Society located in Pasadena.  I am a Swiss citizen and have a biometric passport. However, I don't have any special visa, as there is no visa needed for the school I am attending and using the Visa Waiver Program, I am allowed to stay up to 90 days in the US.  Am I allowed to do volunteer work during my stay? How do I "parent" objects? I'm looking for a way to have two separate objects be connected, so that when I move the first object the second one will move also. The term parent is used, but how do I parent a object? GNOME: disable sleep on lid close Is it possible to stop my laptop going to sleep when I close the lid?  GNOME 3.20, Fedora 24.    My laptop does not reliably wake from sleep.  (It happens to be a hardware issue... I think I basically killed it while trying to replace a wifi card.  But I want to keep using it for a while longer). In the Ubuntu dock on Ubuntu 18.04, multiple windows of the same application are grouped and orange dots are shown to tell you how many windows of the application are opened. When you click on the icon, a small screen capture of each of the windows is shown.  However, these screen captures are shown in an order that's based on which window was last active on the desktop. This is something that clashes with the way I use the dock. I'm used to mentally mapping the windows to their dock positions. As such, I will often be trying to get to "the top one" and then I end up needing several clicks before I actually get to the terminal (or some other application) that I was looking for.  Is there some way to make sure that the order of these screen captures does not change whenever a window becomes active? Which is more correct:     Apropos of your earlier comment, I decided to....   or      Apropos your earlier comment, I decided to...   Actually, apropos is so fancy a word, even I, a word maven if I do say so myself, am not entirely sure when to use it.  If I may add to my preposition question, are there any constructions where it would be appropriate to use something like with regard to and not apropos? Is it possible to create an iron door which responds to levers on both sides The final state of 1000 light bulbs switched on/off by 1000 people passing by There are  1000  light bulbs and 1000 tutors. All light bulbs are off. Tutor 1 goes flipping light bulb 1,2,3,4... tutor 2 then flips 2,4,6,8... tutor 3 then 3,6,9...etc until all 1000 tutors have done this.  What is the status of light bulb 25? 93? 576?  Is there a general solution to find out the status of any light bulb?  How many light bulbs are on after all 1000 tutors have gone by?  Not homework but a UK university interview question. Please help.