A process put to sleep by issuing ^Z can be brought back to the foreground by listing the running jobs $ jobs and giving the job id to fg %id.  But when I tried to list the jobs in a separate screen of the same terminal there was no results. How to achieve this ?  What I want is to start the same process without killing it in a separate screen of the same terminal.
I have detached a process from my terminal, like this:  $ process &amp;   That terminal is now long closed, but process is still running, and I want to send some commands to that process's stdin. Is that possible?
I was wondering how far in imaging physics had gotten. Do we hold the technology to actually take a picture of, say, an alpha particle, or even a single atom?  I realise we aren't talking about camera pictures, so what kind of imaging techniques have taken images/is most likely to be the technique to take an image of a single atom? Let $C_*$ be a chain complex such that each $C_i$ is a torsion-free, finite-range abelian group with $C_i=0$ for all $i&lt;0$. Suppose that $C_i=0$ for all $i$ is large enough. The Euler characteristic of $C_*$ chain complex is defined as $$\chi(C_*)=\sum_{i\geq 0}(-1)^iRank(C_i)$$ Prove that $$\chi(C_*)=\sum_{i\geq 0}(-1)^iRank(H_i(C_*))$$  I have to prove that $\sum_{i\geq 0}(-1)^iRank(C_i)=\sum_{i\geq 0}(-1)^iRank(H_i(C_*))$, I think that one way to do this is by showing that $Rank(C_i)=Rank(H_i(C_*))$ but I do not know if this is true in general, in a nutshell, I want to show that the cardinality of the base of any $C_i$ is the same as the cardinality of the basis of the corresponding homology, how can I do this? Thank you preventDefault() on an  tag Shoenfield introductory mathematical logic book alternatives I was originally intending on reading Mathematical Logic by Joseph R. Shoenfield (1967) though after reading  I get the impression that despite being influential for the time it was written, there now exist many new books written from our current perspective that tend to be easier on non-experts by offering more thorough explanations for each new topic being introduced.   As of now I have a basic knowledge of abstract algebra (basics on vector spaces, rings, groups etc.) from doing elementary number theory and taking a course on linear algebra, also I have completed  a year long course on real analysis which used a lot of elementary set theory and some order theory.   With all that said, I was hoping based on my current basic knowledge of math that someone could recommend me an introductory book on mathematical logic which I could use as an alternative to Shoenfield's and which addresses Peter Smith's criticisms - any help would be greatly appreciated. My friend and I have been wracking our heads with this one for the past 3 hours... We have 2 point masses, $m$ and $M$ in a perfect world separated by radius r.  Starting from rest, they both begin to accelerate towards each other. So we have the gravitational force between them as:  $$F_g ~=~ G\frac{Mm}{r^2}$$  How do we find out at what time they will collide?  What we're having trouble with is this function being a function of $r$, but I have suspected it as actually a function of $t$ due to the units of $G$ being $N(m/kg)^2$.  I've tried taking a number of integrals, which haven't really yielded anything useful.  Any guidance?  No, this is not an actual homework problem, we're just 2 math/physics/computer people who are very bored at work :) Checking to see if a user has a licence for a managed package So I'm aware that there is a method on UserInfo called isCurrentUserLicensed which lets you check if the user running the code has a licence for a namespace that you specify, i.e. for a particular managed package.  What I want to know is whether there is a way I can test to see if some other user (assume I have their ID) has a licence for a particular package. Has anybody found a way to do this? 18.04: color emoji not showing up at all in Chrome, only partially in Firefox Why would you not want to rollover a previous employer's 401(k) when changing jobs? Are there any valid reasons to not rollover a former 401(k) when changing jobs?  I have several little ones that I never quite got around to rolling together - with an upcoming job change, should they all be combined into my new employer's retirement plan?  If not, what else might be considered? British Airways (BA) just changed our flight times, leaving us only 1h15mins for our layover in Heathrow. We arrive from Brussels in terminal 5 in Heathrow at 7:55 and our next flight leaves for Miami in Heathrow terminal 3 at 9:10.  This seems awfully short.   Does anyone know whether this is doable?   The flights are in November, so I'm still hoping that the flights will change back to the original flight times, which would give us an additional hour for the layover, but in case this does not happen, what are the chances that we will make the connecting flight in 1h15mins? For $f$ in dual space, there exists $x$ with norm 1 and $f(x)=\|f\|$ if space is reflexive (and nontrivial) Let $X\ne\{0\}$ be a reflexive space and let $f\in X^*$, where $X^*$ is the dual of $X$. I want to know: in general, does there exist an $x\in X$ with $\|x\|=1$, and $f(x)=\|f\|$, where $\|f\|$ is defined as $\sup\{|f(x)|:x\in X,\|x\|=1\}$?  I know this is true for $\mathbb{R}^n$ with the norm from the standard inner product, but I'm wondering if it is true in general. Class imbalance strategies When dealing with the class imbalance problem in a binary classifier, there are three ways I know of to address it: over-sampling, under-sampling and using cost-sensitive methods.   Are there any guidelines, rules of thumb or general strategies to choose among these methods? A possible answer would be: over-sample when the positive class has more than 100 instances (I just made it up). How does the Java 'for each' loop work? In what order are the dated ordered by? Certainly not alphanumeric order.  ls -lt sorts by modification time. But I need creation time. How do you retrieve items from a dictionary in the order that they're inserted? Is it possible to retrieve items from a Python dictionary in the order that they were inserted? How to manage memory alignments and generic pointer arithmetics in a portable way in C? unicode-math broken I'm making a trip back home (to the coast) shortly, and I would like to bring back sand from the beach with me as a keepsake or memento. It's just a short weekend trip, and I won't be checking any luggage, so I was wondering if it's even worth bothering trying to bring sand aboard the plane in my carry-on?  If so, what can I do to make the security screening as smooth as possible? I was planning on putting the sand in sandwich-sized plastic bags, enclosed in a larger quart- or gallon-sized bag. Integral Inequality $|f''(x)/f(x)|$ Let $f$ be a $C^2$ function in $[0,1]$ such that $f(0)=f(1)=0$ and $f(x)\neq 0\,\forall x\in(0,1).$ Prove that  $$\int_0^1 \left|\frac{f{''}(x)}{f(x)}\right|dx\ge4$$ Bind variable with dotted name not working in dynamic SOQL As mentioned in , it's possible to use bind variables in dynamic SOQL queries.  This seems like a great way to avoid SOQL-injection, and to build a query string once but use it multiple times with different values in the variables.  I'm working on a method that returns a list of objects.  It accepts a class with multiple properties as its only parameter.  The properties of this class are used to filter the results to just the required records.  It will eventually be driven by a Visualforce component, which will be configured by querystring parameters in the URL.  I just ran into an issue where the query fails when I use dotted bind variables.  If I copy the constructed dynamic SOQL into a static query, it works fine.  This may be a bug, because in doing tests I found that :foo.bar would actually try to use local variable bar.  Here's one of my queries, which uses related custom objects.  I've stripped it down to just the part that's failing (wrapped for legibility):  result = Database.query('SELECT Name, Another_Object__r.Name,      Another_Object__r.Custom_Field__c      FROM Custom_Object__c       WHERE Another_Object__r.Custom_Field__c = :filter.deviceType');   The error reported is System.QueryException: Variable does not exist: filter.deviceType.  As mentioned above, the query works fine as static SOQL, just not dynamic:  result = [SELECT Name, Another_Object__r.Name, Another_Object__r.Custom_Field__c FROM Custom_Object__c WHERE Another_Object__r.Custom_Field__c = :filter.deviceType];   It also works in this case:  String deviceType = filter.deviceType; Database.query('SELECT Name, Another_Object__r.Name, Another_Object__r.Custom_Field__c FROM Custom_Object__c WHERE Another_Object__r.Custom_Field__c = :deviceType');   I haven't read about this being a known limitation.  I don't know if I should be using some other syntax/notation in the query -- the dotted notation appears correct.  Time to report a bug?  Thoughts on workarounds other than creating local variables to stand in for each member of the class? Pattern in Isomorphisms between $\mathbb Z_m \times \mathbb Z_n$ and $\mathbb Z_{mn}$