When Snap updates a program it keeps the before versions installed. For example, I had Skype installed with the 60 version ( 567 MB ),but then it was updated with 63 version (606 MB) and finally the actual 66 version ( 607 MB ). As is the program uses 1.7 GB in the hard disc. If an user has in his system a few programs installed using Snap, probably it doesn't a big problem but if the idea is that in the future the most program is istalling as is, it will use a lot of space in the hard disc, and the process won't be efficient. If I uninstall Skype and re install again, it uses only 607 MB. If this issue is not known, how can I comunicate to Ubuntu programers to review it and try to improve the process ?
So I installed vlc daily built snap package. It's working great, no problems there. However I noticed that after upgrade the system has 2 versions of vlc (7 and 9). That can be seen when browsing /snap/vlc/ directory and using system monitor. This is also the case with other snaps. Is there a way to automatically delete older versions of snaps? Or do I just delete them using plain &quot;rm&quot; command? Is it safe to delete them that way?
Set shortcuts to change keyboard layout in Windows 10? Is there any way to set keyboard shortcuts to quickly change to a different language/keyboard layout? The old shortcuts still seem to work (when set back in Windows 7), but I can't seem to find anything to change it in Windows 10. I have a 16GB flash drive. I'm running Ubuntu 14.04. I can't open my flash drive and I can't see it in GParted.  After running tail -f /var/log/syslog . After inserting my flash:  USB disconnect, device number 10 Jul  3 16:39:55 rihanna-VGN-Z56GG-B kernel: [ 3309.712166] usb 2-3: new high-speed USB device number 11 using ehci-pci Jul  3 16:39:55 rihanna-VGN-Z56GG-B kernel: [ 3309.846591] usb 2-3: New USB device found, idVendor=090c, idProduct=1000 Jul  3 16:39:55 rihanna-VGN-Z56GG-B kernel: [ 3309.846601] usb 2-3:   New USB device strings: Mfr=1, Product=2, SerialNumber=3     Jul  3 16:39:55 rihanna-VGN-Z56GG-B kernel: [ 3309.846609] usb 2-3: Product: Silicon-Power     Jul  3 16:39:55 rihanna-VGN-Z56GG-B kernel: [ 3309.846615] usb 2-3: Manufacturer: UFD 2.0     Jul  3 16:39:55 rihanna-VGN-Z56GG-B kernel: [ 3309.846622] usb 2-3: SerialNumber: 1401208423400131     Jul  3 16:39:55 rihanna-VGN-Z56GG-B kernel: [ 3309.847176] usb-storage 2-3:1.0: USB Mass Storage device detected     Jul  3 16:39:55 rihanna-VGN-Z56GG-B kernel: [ 3309.847309] scsi12 : usb-storage 2-3:1.0     Jul  3 16:39:55 rihanna-VGN-Z56GG-B mtp-probe: checking bus 2, device 11: "/sys/devices/pci0000:00/0000:00:1d.7/usb2/2-3"     Jul  3 16:39:55 rihanna-VGN-Z56GG-B mtp-probe: bus: 2, device: 11 was not an MTP device     Jul  3 16:40:17 rihanna-VGN-Z56GG-B kernel: [ 3332.176107] usb 2-3: reset high-speed USB device number 11 using ehci-pci     Jul  3 16:40:33 rihanna-VGN-Z56GG-B kernel: [ 3347.288080] usb 2-3: device descriptor read/64, error -110     Jul  3 16:40:48 rihanna-VGN-Z56GG-B kernel: [ 3362.504081] usb 2-3: device descriptor read/64, error -110     Jul  3 16:40:48 rihanna-VGN-Z56GG-B kernel: [ 3362.720076] usb 2-3: reset high-speed USB device number 11 using ehci-pci     Jul  3 16:40:52 rihanna-VGN-Z56GG-B kernel: [ 3366.812110] usb 2-3: reset high-speed USB device number 11 using ehci-pci     Jul  3 16:41:07 rihanna-VGN-Z56GG-B kernel: [ 3381.924082] usb 2-3: device descriptor read/64, error -110     Jul  3 16:41:23 rihanna-VGN-Z56GG-B kernel: [ 3397.356093] usb 2-3: reset high-speed USB device number 11 using ehci-pci     Jul  3 16:41:38 rihanna-VGN-Z56GG-B kernel: [ 3412.468057] usb 2-3: device descriptor read/64, error -110     Jul  3 16:41:54 rihanna-VGN-Z56GG-B kernel: [ 3428.664065] usb 2-3: reset high-speed USB device number 11 using ehci-pci     Jul  3 16:42:09 rihanna-VGN-Z56GG-B kernel: [ 3443.776100] usb 2-3: device descriptor read/64, error -110     Jul  3 16:42:24 rihanna-VGN-Z56GG-B kernel: [ 3458.992085] usb 2-3: device descriptor read/64, error -110     Jul  3 16:42:25 rihanna-VGN-Z56GG-B kernel: [ 3459.208063] usb 2-3: reset high-speed USB device number 11 using ehci-pci     Jul  3 16:42:40 rihanna-VGN-Z56GG-B kernel: [ 3474.320039] usb 2-3: device descriptor read/64, error -110     Jul  3 16:42:50 rihanna-VGN-Z56GG-B kernel: [ 3484.516109] usb 2-3: reset high-speed USB device number 11 using ehci-pci     Jul  3 16:42:50 rihanna-VGN-Z56GG-B kernel: [ 3484.768108] usb 2-3: reset high-speed USB device number 11 using ehci-pci Jul  3 16:43:05 rihanna-VGN-Z56GG-B kernel: [ 3499.880081] usb 2-3: device descriptor read/64, error -110 Jul  3 16:43:20 rihanna-VGN-Z56GG-B kernel: [ 3515.096081] usb 2-3: device descriptor read/64, error -110 Jul  3 16:43:21 rihanna-VGN-Z56GG-B kernel: [ 3515.312048] usb 2-3: reset high-speed USB device number 11 using ehci-pci Jul  3 16:43:36 rihanna-VGN-Z56GG-B kernel: [ 3530.424032] usb 2-3: device descriptor read/64, error -110 Jul  3 16:43:46 rihanna-VGN-Z56GG-B kernel: [ 3540.505230] scsi 12:0:0:0: Device offlined - not ready after error recovery Show that $\textbf{ZF}$ shows $\phi$ is $\Delta_1$ I am using an iPhone 6s with iOS 12.4 and a MacBook Pro mid2015 with macOS 10.14.6. Since recently (I am not exactly sure when it started), I cannot charge the phone with my computer anymore. As soon as I plug the phone in, it will play the charging sound repeatedly. The right-hand side port sometimes works, the lefthand side port never works. When I connect my old iPhone 5 (using the same cable), it charges without any issues. My iPad mini 4 shows the same issue.  Sometimes the "Do you trust this computer" setting flashes on the phone and disappears before I can click anything.   How can I fix this?  Update 1  Sometimes I get the Software Update dialogue in macOS. After approx. 2 minutes it shows the following:     Update 2  For some reason the issue disappeared for a while but is back now. Disabling "Settings" > "Touch ID &amp; Passcode" > "USB Accessoires" seems like it makes the problem a bit less bad, but not go away.  Update 3  This is driving me crazy. I upgraded to Mojave 10.14.3 mostly to get rid of the issue. It persists. Some more random information: Before logging in (Filevault pre-boot authentication), the phone will charge fine. Only when a user account is loaded, the issue appears. The likelihood of a successful connection increases with the battery state of the iPhone. Workaround 2 in my answer below suggest that this a "Trust issue" from the iPhone's side. I suppose the solution will have to be hidden somewhere there...    What I tried so far (will update):   Reset Privacy settings on iPhone Different (original, almost new Apple) lightning cables   Remove and add "iPhone USB" in Network Settings  SMC reset (), PRAM reset Upgrade to latest iOS 12.4 and MacOS 10.14.6 Present Perfect vs. Present Perfect Continuous how are you?  Well, my biggest doubt at the moment is the difference between these two tenses. Actually, the more I study the more I have doubts with these tenses.      /         These similar threads helped me to clarify and reiterate my previous understanding.   I'm not posting in these threads because the site suggests avoiding asking for clarification (I don't know why because it would avoid new threads with the same content).  My main doubt is as follows:     I've lived in New York for two years.   In my understanding, the sentence above implies (1) that I lived in NY for two years and now I live in another place; or (2) I'm moving to another city after two years living in NY; or (3) I lived in NY for two years, then I moved to another place for some period and, finally, I'm returning. Is that correct?     I've been living in New York for two years.   Whereas the sentence above, in my understanding, implies that I lived in NY for two years and I still living there.  Anyway, many sources that I've already read say that these two sentences have the same meaning and are interchangeable. Therein lies my question. Is that correct? Because if these two sentences are interchangeable, it destroys all my understanding.  Thanks in advance. I've been stuck on this problem for about an hour.     In an ideal transformer, the same flux passes through all turns of the primary and of the secondary . Show that in this case $M^2=L_1L_2$, where $M$ is the mutual inductance of the coils, and $L_1$, $L_2$ are their individual self-inductances.   My first instinct was the following: If we isolate the response of each coil to the other one, we get the equations $N_1\Phi_1=MI_2$ and $N_2\Phi_2=MI_1$, where $\Phi$ is magnetic flux going through a single turn of the coil and $I$ is current. Likewise, if we isolate the response of each coil to itself, we get the equations $N_1\Phi_1=L_1I_1$ and $N_2\Phi_2=L_2I_2$. I would now naturally want to say "Now just multiply $N_1\Phi_1$ and $N_2\Phi_2$ both ways, and get the desired result!" i.e.,  $$(N_1\Phi_1)(N_2\Phi_2)=(MI_2)(MI_1)=(L_1I_1)(L_2I_2)\implies M^2=L_1L_2$$  But that's incorrect, because the response of the coils to themselves and to the other coil are different quantities (i.e. not necessarily equal).  Realizing this, I write down the more general equations.  $$N_1\Phi_1=MI_2+L_1I_1$$ $$N_2\Phi_2=MI_1+L_2I_2$$  Now even with the hypothesis that $\Phi_1=\Phi_2=\Phi$, I still can't see how the identity $M^2=L_1L_2$ follows. Could you help clear up my confusion?  *Taken from D. Griffiths Introduction to Electrodynamics (4th ed.), Problem 7.58. How to fix very slow Ubuntu booting? When I boot up my my newly installed copy of Ubuntu on my custom rig w/4GB DDR3 RAM and a 3 Ghz Intel Core i7, it takes about a minute and a half at the purple loading screen, and then after logging in it takes a while for the icons to show up on the screen. This computer could run and boot Windows 7 faster, so  i have a problem here. In a table, how can I draw a horizontal line that goes only through some of the cells? I mean a line like the one in the Foo and in the Bar area of this table:  +----+-----+ |Foo |1 |2 | |    |1 |2 | |    +--+--+ |    |1 |2 | |    |1 |2 | +----+-----+ |Bar |1 |2 | |    |1 |2 | |    +--+--+ |    |1 |2 | |    |1 |2 | +----+--+--+ How to display Trash and Home folder icons? I've googled quite a bit but nothing I've found works. I just want to display the Trash, Home folder, Computer etc icons on my Desktop in Ubuntu.  The closest I've come is installing dconf-tools, running it, going to org -&gt; gnome -&gt; desktop -&gt; background and checking show-desktop-icons then org -&gt; gnome -&gt; nautilus -&gt; desktop and checking the icons I want to show.  Nothing happens.  I've also tried looking in compizconfig-settings-manager and gconf-editor but can't find anything there.  Ideas? What is time dilation really? Identify which OrgWideEmailAddress records are valid for current user I'd like to create a popup list on one of my Visualforce pages, for a user to select from a list of OrgWideEmailAddress records.  My goal is to limit the list to only those records that they're allowed to use.  I'm going to save the selection for use in later automatic emails.  Based on what I've read, I won't be able to send emails to certain OrgWideEmailAddresses:   The address hasn't been verified yet.  I don't see any fields in the schema that appear to show verification state. The address is only available to profiles that the user isn't a member of.  I don't see where the profile list is stored for each record.   Some of my problem could just be due to not understanding the standard objects so well, and perhaps there's a way to get at this through UserInfo, or by making my query on the User object which may have a child relationship to OrgWideEmailAddress since it's listed in the schema viewer of the Force.com IDE.  Here's the test code I'm working with:  for (OrgWideEmailAddress addr : [SELECT DisplayName, Address          FROM OrgWideEmailAddress ORDER BY DisplayName]) {     System.debug( addr.DisplayName + ' &lt;' + addr.Address + '&gt;'); }   I tried creating a new Messaging.SingleEmailMessage and then calling setOrgWideEmailAddressId() on it with each OrgWideEmailAddress Id, in hopes that invalid Ids would throw an exception, but to no avail.  My goal is to modify the test code to provide just the subset of records that the current user will be able to use. Why can I not place a pregnant woman to work but others work while pregnant? I am playing Fallout Shelter, have 3 kids in my shelter, all going well, thought I would make one more kid with big strength numbers and decent agility/perception (kids take on SPECIAL stats from their parents). All the women who are pregnant work in my shelter, apart from this one. She can not me put to work, can not be moved from the living shelter, can not be moved to a job via the clipboard short cut.  TL;DR One of the NPC females who is pregnant can not be put to work, can not be moved from the living shelter room, she just walks about as if she is carrying a mammoth inside her. I have NOT moved the shelter, have not let the dad die, have not done anything at all. Prove QM-AM inequality $$\dfrac{x_1^2+ x_2^2 + \cdots + x_n^2}n \geq \left(\dfrac{x_1+x_2+\cdots+x_n}n\right)^2$$   I don't think AM, GM can be used here. And simple expansion doesn't help too. What should I do? Conjugate Variables, Noether's Theorem and QM Registry key / GPO to disable and block Windows 10 upgrade? How do I save a file with managed_file in a theme? I'm developing a theme that it requires to have a header image on the front page, so I have this.  casper.theme  function casper_form_system_theme_settings_alter(&amp;$form, &amp;$form_state) {  $form['theme_extra']['front_page_background_image'] = array(     '#type' =&gt; 'managed_file',     '#title' =&gt; 'Front Page Background Image',     '#description' =&gt; 'Add background image for the front page',     '#required' =&gt; FALSE,     '#weight' =&gt; -4,     '#upload_location' =&gt; file_default_scheme() . '://theme/backgrounds/',     '#default_value' =&gt; theme_get_setting('front_page_background_image' , 'casper'),     '#upload_validators' =&gt; array(         'file_validate_extensions' =&gt; array('gif png jpg jpeg'),     ),  ); }   However, after it, while the file been missing and after some reading, I find out that is because managed_file does not save your image permanent.   There are similar questions:    is specified to Drupal 7.  is using "file" type instead of managed_file. I already tried something similar to what the Mayo theme is doing, but I was not able to successfully figure it out.   How can I save my image permanently? $A_n$ is the only subgroup of $S_n$ of index $2$. How to prove that the only subgroup of the symmetric group $S_n$ of order $n!/2$ is $A_n$?  Why isn't there other possibility?  Thanks :) Difference between ref and out parameters in .NET Does everything with mass or energy have a gravitational pull? Show an Ideal is the principal ideal for some polynomial. Let $F$ be a ﬁeld and $R = F[X]$. Suppose $I$ is an ideal of $R$. Show that $I = (p(X))$ for some $p(X)$ in $F[X]$. (Hint: consider a polynomial $p(X)$ of least degree in $I$.)  I'm trying to do this question but can't seem to start. if anyone could give me a hint that would be appreciated.  My instinct was to take a monic polynomial (which exists since we are in a field) of degree $1$ and divide given the first two parts of the question were about polynomial division.  Thanks.