how to access to lost process?
Can I nohup/screen an already-started process?
How do I upgrade to the unreleased version of Ubuntu for testing? I found it in an old dictionary and I'm not sure what it means. It looks like the number &quot;3&quot;, but the top of the three has been flattened(and slightly curved). I've only seen this in three or four words. [] We know that the trace of a matrix is a linear map for all square matrices and that $\operatorname{trace}(AB)=\operatorname{trace}(BA)$ when the multiplication makes sense.   On the , under properties, it says that these properties characterize the trace completely in the following sense: If $f$ is a linear function on the space of square matrices satisfying $f(xy)=f(yx)$, then $f$ and $\operatorname{tr}$ are proportional. A  of the page gives the justification, but I do not understand the logic of it. Thanks A Regular Tetrahedron is a cool Polyhedron. A regular tetrahedron has this property:  For any two of its vertices exists a third vertex, which forms a regular triangle with these 2 vertices.(It doesn't necessarily have to be a face of it).  Are there any other polyhedrons that have the same property?  I think there isn't such a polyhedron. But not sure how to prove it. I've tried proving that there isn't an irregular tetrahedron with this property, assuming that there is a pair of unequal sides.   Current answers are a little confused with the conditions of the problem. Finding information on German soldiers from World War I and World War II? Where can I find information on German soldiers from World War I and World War II?   I am curious to find out about my ancestors' role in the wars, i.e. what rank they had, where they where fighting, with whom and anything else. Crash adding comment The SE iOS app crashes when adding comments to certain posts.  It was discovered to be if the "Add an Answer" button was visible, not just responding to a deleted comment.  Edited to match answer. Previous steps were not the only use case, and this error keeps getting re-reported in different ways. How's This for a Simple HTTP Callout Retry Framework? Most of what I have read about retry operations is that they are vaguely complicated and indepth. I have written the code below which seems to accomplish this without too much confusion - I'm wondering if there are any pitfalls I am not seeing here.   The class uses a top-level schedulable class, which calls a queueable class to make the callout, and if the callout is unsuccessful, it just schedules the top level class again five minutes later. After testing it appears this works indefinitely.   A simple string token, assigned at the first invocation, is also passed between the classes, and I have tested and found that the token does persist, even when runs are scheduled for a later time.   Thanks for helpful thoughts!  public class SelfServe implements Schedulable {      public String Token = null;      public void execute(SchedulableContext ctx) {                  RetrieveMachineDetails Job = new RetrieveMachineDetails();             Job.Token = Token;             System.enqueueJob(Job);      }           public class RetrieveMachineDetails implements Queueable, Database.AllowsCallouts {          public String Token = null;          public void execute(QueueableContext context){                                            Http http = new Http();             HttpRequest request = new HttpRequest();                             request.setEndpoint('https://app.endpoint.com/api');                     request.setMethod('POST');                     request.setHeader('Content-Type', 'application/json;charset=UTF-8');                                      request.setBody('{"query":  "$message_=\'METRIC\' &amp;&amp; $tier=\'customer\' "}');                                                                                                                                                                                    HttpResponse response = http.send(request);                            if (response.getStatusCode() == 200) {                 //do stuff                  }              else { //retry                  DateTime Dt = system.now().addMinutes(5);                                String day = string.valueOf(Dt.day());                                        String month = string.valueOf(Dt.month());                                          String hour = string.valueOf(Dt.hour());                                       String minute = string.valueOf(Dt.minute());                                                       String year = string.valueOf(Dt.year());                                   String ScheduledTime = '0 ' + minute + ' ' + hour + ' ' + day + ' ' + month + ' ?' + ' ' + year;                  SelfServe Job = new SelfServe();                     Job.Token = Token;                 System.schedule('SelfServe Job'+Dt, ScheduledTime, Job);              }         }        }  } Example of a function such that $\varphi\left(\frac{x+y}{2}\right)\leq \frac{\varphi(x)+\varphi(y)}{2}$ but $\varphi$ is not convex How to list all functions in a Python module? Function with limits only at irrational points This is the starred example 5.1.8 in Krantz' Real Analysis and Foundations.     Give an example of a function $f: \mathbb{R} \rightarrow \mathbb{R}$ so that $\lim_{x\rightarrow c} f(x)$ exists when $c$ is irrational but does not exist when $c$ is rational.   I'm aware of the Dirichlet and Thomae functions but this seems slightly different. I'm not even sure a solution exists. Thanks for any help! When is the Killing form null? When is the Killing form $\kappa$ of a Lie algebra $\mathfrak g$ null, i.e. $\kappa(\cdot,\cdot)=0$? Surely this is true for any Lie algebra with trivial bracket, but is this the only case? I can't seem to find any nontrivial examples. Can Windows Virtual PC run a 64-bit OS? Rational solutions of $y^2 = x^3 - x$ Best way to remove an event handler in jQuery? I have an input type="image". This acts like the cell notes in Microsoft Excel. If someone enters a number into the text box that this input-image is paired with, I setup an event handler for the input-image. Then when the user clicks the image, they get a little popup to add some notes to the data.  My problem is that when a user enters a zero into the text box, I need to disable the input-image's event handler. I have tried the following, but to no avail.  $('#myimage').click(function { return false; }); Do file-extensions have any purpose (for the operating system)? How can I propose a new site? Chrome Extension Message passing: response not sent A borderline between on-topic questions and questions about library recommendation? I have a consideration about new off-topic close reason:     Questions asking us to recommend a tool, library or favorite off-site   resource are off-topic for Stack Overflow as they tend to attract   opinionated answers and spam. Instead, describe the problem and what   has been done so far to solve it.   For example take that question:   It has a close vote with the reason above. But if it would be formed     How to zoom image in an absolute position div to the side?   The answer would be probably also a jQuery plugin or javascript library, but it would follow the patter of most questions about jQuery.  Take that question:   This is the good question about real-life problem. The answer is to use a maven plugin. It is correct, there's no need to reinvent the wheel or rediscover the America.   But  I'm afraid the off-topic text could be misleading and could be misused to close such a questions as that about maven simply because a tool, library or plugin is the answer.   Is it a new guideline that the questions such as cited above should be banned, no matter how they are formed (this would make most how-to-do-in-maven/jquery) questions illegal? Or the close reason should be changed to make more clear what the guidelines are (it's not clear to me now)? Compiling the following code and got the error of type illegal.  int main() {     // Compilation error - switch expression of type illegal     switch(std::string("raj"))     {     case"sda":     } }   You cannot use string in either switch or case. Why? Is there any solution that works nicely to support logic similar to switch on strings? How can I subdivide this plane into even squares?