While playing around with a fresh installation of 18.04, I've accidentally selected a photo for my user. I couldn't find an undo or cancel or remove option, so now I'm stuck with a photo on the login screen. Is there any way to return to the default faceless gray avatar?  My workaround would be to create a new user, grab a screenshot, cut the default image and use that as my new "photo" but if there's a real removal option I'd love to know about it.  Update: I did not take a photo with the webcam, just selected one of the provided images, so there is no .face file in my home directory.
A similar task for changing the desktop background, can be achieved using the following script:   FILE="/backgrounds/background.png" gsettings set org.gnome.desktop.background picture-uri "$FILE"   How would I achieve the same result, but with the user's avatar/profile picture?
Why is $\omega$ the smallest $\infty$? I am comfortable with the different sizes of infinities and Cantor's "diagonal argument" to prove that the set of all subsets of an infinite set has cardinality strictly greater than the set itself. So if we have a set $\Omega$ and $|\Omega| = \aleph_i$, then (assuming continuum hypothesis) the cardinality of $2^{\Omega}$ is $|2^{\Omega}| = \aleph_{i+1} &gt; \aleph_i$ and we have $\aleph_{i+1} = 2^{\aleph_i}$.  I am fine with these argument.  What I don't understand is why should there be a smallest $\infty$? Is there a proof (or) an axiom that there exists a smallest $\infty$ and that this is what we address as "countably infinite"? or to rephrase the question "why can't I find a set whose power set gives us $\mathbb{N}$"?  The reason why I am asking this question is in "some sense" $\aleph_i = \log_2(\aleph_{i+1})$. I do not completely understand why this process should stop when $\aleph_i = \aleph_0$.  (Though coming to think about it I can feel that if I take an infinite set with $\log_2 \aleph_0$ elements I can still put it in one-to-one correspondence with the Natural number set. So Is $\log_2 \aleph_0 = \aleph_0$ (or) am I just confused? If $n \rightarrow \infty$, then $2^n \rightarrow \infty$ faster while $\log (n) \rightarrow \infty$ slower and $\log (\log (n)) \rightarrow \infty$ even slower and $\log(\log(\log (n))) \rightarrow \infty$ even "more" slower and so on).  Is there a clean (and relatively elementary) way to explain this to me?  (I am totally fine if you direct me to some paper (or) webpage. I tried googling but could not find an answer to my question) Which facility upgrade unlocks maneuver nodes in KSP Which  unlocks  in career mode in KSP?  The  hints that maneuver nodes are now unlocked with a facility upgrade:     Are there any perks for upgrading?      The building in question   will upgrade visually, both from the outside and the inside. More   gameplay mechanics will be also be unlocked as the player progresses   through the different building tiers. For example, allowing EVAs in   space or being able to use maneuver nodes in the map view. I have just installed Ubuntu 16.04 32-bit.   When I opened its software store, I found that it's not showing the apps I installed in Ubuntu 15.10 like Clementine, Gdebi package installer or synaptic package manager, dconf, acetoneiso etc.   I need these applications. How can I install them? Why is the Petersen graph no Cayley graph? Java: Sorting user-input array upon return Can Minecraft Pocket Edition play with a desktop Minecraft? What is the symbol on the supply voltage that looks like a shaded-in capacitor? I am looking at  (dual low-voltage power amplifier). On the fourth page, there is a sample circuit; right at the V+ input there is a symbol that looks like a capacitor. However, it looks like it is shaded in. What is that? How to merge cells vertically Is it possible to create a table like this one?    The usual structure of tables I use looks like this:  \begin{table}[H]     \begin{adjustbox}{width=\textwidth,center}     % \begin{adjustbox}{center}         \begin{tabular}{lll}             \hline             \multicolumn{1}{l}{\head{XXX}} &amp; \multicolumn{1}{l}{\head{XXX}} &amp; \multicolumn{1}{l}{\head{XXX}} \\             \hline             \ttfamily xxx &amp; \ttfamily xxx &amp; \ttfamily xxx \\             \hline         \end{tabular}     \end{adjustbox}     \vspace{ - 05 mm}     \caption{xxx}     \label{tab:xxx} \end{table} How can I see flags I cast from all sites? This morning I flagged something on one of the sites where I have fairly low rep. Now I can't remember which site it was. I've checked my flag history on about half of them, even editing the URL for the site where I have no helpful flags, and I can't find this flag. I've been to my network profile and looked at the Activity tab, but it only shows public things like asking, answering, commenting, editing, and reviewing.  Is there a way to see my flagging history across sites? Can we have such a feature, if it's not possible? Short story about aliens that are parts of a spaceship 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. right now when I connect to my VPN, my internet is served from my home router, but any requests for xxx.xxx.xxx.xxx i.e. my works ip range are served via the vpn connection I believe.  How can I force all traffic to the vpn? I am trying to install reaver 1.4, but when I run ./configure ; make I get this message at the end  int ret_val = EXIT_FAILURE, r = 0;   I have searched a fair bit and cannot find an answer, any help would be appreciated. I apologize if this has been answered and I've just failed to find it. ARMA/GARCH estimation in sequence I have a time series that shows a nonstationary seasonal autoregressive component as well as known heteroshedasticity. In order to model the series, I have fit a seasonal ARIMA model for the mean with the auto.arima model in the forecast package in R and a GARCH model on the residuals of the ARIMA model.   Is the procedure of sequentially estimating ARIMA and GARCH model correct or would it have been better to jointly model the mean and the variance of the series? If this were correct, is there a (possibly R) function to do it? Sort by author in Alpha bibliography ShellExecuteEx code 31 error any time I try to launch an EXE, how to find problematic driver? Finite ring has only zero divisors and units If a nonzero element $a$ of a ring $\mathbb{D}$ does not have a multiplicative inverse, then $a$ must be a zero divisor.   If $\mathbb{D}$ has finitely many elements, then the statement is true. However, I don't see why, as for the infinite case, 7 isn't a zero divisor only because every element $a &gt; 0$ when multiplied by a $b &gt; 0$ gives you $ab &gt; 0$ which has nothing to do with infinity or finite amounts of elements. Missing SOAP action header Im trying to get the session ID of another user in the same org by sending the following request by using the data from my enterprise wsdl and its an developer edition.  &lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:enterprise.soap.sforce.com"&gt;    &lt;soapenv:Header&gt;       &lt;urn:organizationId&gt;xxxxxxx&lt;/urn:organizationId&gt;    &lt;/soapenv:Header&gt;    &lt;soapenv:Body&gt;       &lt;urn:login&gt;          &lt;urn:username&gt;xxxxxxxxx&lt;/urn:username&gt;          &lt;urn:password&gt;xxxxxxxxx&lt;/urn:password&gt;       &lt;/urn:login&gt;    &lt;/soapenv:Body&gt; &lt;/soapenv:Envelope&gt;   But when i send this request i get      Missing SOAP ACTION header  but in my wsdl i dont have the action ,its blank    how to overcome this problem ?I got totaly struck over here since there is no action though its asking for action header.Following method handles the http request.   public string   processrrequest(string ep,string message,string method) {      HttpRequest req = new HttpRequest();     req.setEndpoint(ep);     req.setMethod(method);     req.setHeader('Content-Type', 'text/xml');     req.setHeader('SOAPAction','');     req.setBody(message);     system.debug('Request::'+req.getbody());     Http http = new Http();     HttpResponse res =http.send(req);     //Dom.Document doc  = res.getbodyDocument();     system.debug('Response::'+res.getbody());     system.debug('Response2::'+res.getStatus());     Dom.Document doc= new Dom.Document();     doc=res.getBodyDocument();     system.debug('doc::'+doc);     return 'hai'; } After discussion with colleagues regarding the use of the 'var' keyword in C# 3 I wondered what people's opinions were on the appropriate uses of type inference via var?  For example I rather lazily used var in questionable circumstances, e.g.:-  foreach(var item in someList) { // ... } // Type of 'item' not clear. var something = someObject.SomeProperty; // Type of 'something' not clear. var something = someMethod(); // Type of 'something' not clear.   More legitimate uses of var are as follows:-  var l = new List&lt;string&gt;(); // Obvious what l will be. var s = new SomeClass(); // Obvious what s will be.   Interestingly LINQ seems to be a bit of a grey area, e.g.:-  var results = from r in dataContext.SomeTable               select r; // Not *entirely clear* what results will be here.   It's clear what results will be in that it will be a type which implements IEnumerable, however it isn't entirely obvious in the same way a var declaring a new object is.  It's even worse when it comes to LINQ to objects, e.g.:-  var results = from item in someList               where item != 3               select item;   This is no better than the equivilent foreach(var item in someList) { // ... } equivilent.  There is a real concern about type safety here - for example if we were to place the results of that query into an overloaded method that accepted IEnumerable&lt;int&gt; and IEnumerable&lt;double&gt; the caller might inadvertently pass in the wrong type.  var does maintain strong typing but the question is really whether it's dangerous for the type to not be immediately apparent on definition, something which is magnified when overloads mean compiler errors might not be issued when you unintentionally pass the wrong type to a method. How can I prove that prove $n^5 - n$ is divisible by $30$? I took $n^5 - n$ and got $n(n-1)(n+1)(n^2+1)$ Now, $n(n-1)(n+1)$ is divisible by $6$. Next I need to show that $n(n-1)(n+1)(n^2+1)$ is divisible by $5$. My guess is using Fermat's little theorem but I don't know how.