I acctualy work on C project compiling with gcc. I can do error checking thought file, but I want to know how to do it inline. gcc -o test.exe test.c;./test.exe  I want to exec test.exe only if no errors in compilling. Like if [gcc -o test.exe test.c no error] =&gt; ./test.exe
I often see tutorials online that connect various commands with different symbols. For example:  command1 |  command2 command1 &amp;  command2 command1 || command2     command1 &amp;&amp; command2   Others seem to be connecting commands to files:  command1  &gt; file1 command1  &gt;&gt; file1   What are these things? What are they called? What do they do? Are there more of them?    .
How prove this equation $\alpha=\aleph_{0}\alpha$ Question:     let $\alpha$ be a infinite cardinal , show that:   $$\alpha=\aleph_{0}\alpha$$   where $\aleph_{0}$ is the cardinality of the natural numbers is denoted aleph-null   this equation is from a book,and I can't prove it,and the author say this is important equation,and can't prove it.Thank you for you help How TDD-oriented is the SE team? Stack Exchange is my role-model for application development.  I've tried to learn as much as possible from the blog and podcasts, from thought process to design, architecture, convention, etc etc.  I'm just about to wrap my head around TDD and am curious about how the SE team approaches it.  Is there a methodology that all team members follow, or is it more developer-driven testing where you pick complex bits to unit test as needed, or is it more about catch-all integration testing once a piece of functionality is done, or... ?  Any input would be fantastic. How do I set focus follows mouse? Is there a way to set up "focus follows mouse" behavior in Unity? Copy complete structure of a table Using some methods, when you create a copy of a table you lose indexes, PK, FK, etc. For example in SQL Server I can say:  select * into dbo.table2 from dbo.table1;   This is just a simple copy of the table; all of the indexes / constraints are missing. How can I copy a table structure (without using a backup)?  I am primarily looking to do this manually, but if that's not possible I'll accept any solution. The correct omission of the definite and indefinite articles How to adjust the breaking in the bibliography? How to run ffmpeg from command line in android If every compact set is closed, then is the space Hausdorff? So, we know that there is no "natural" isomorphism between a finite dimensional vector space $X$ and its dual $X^{\vee}$. However, given a basis for $X$ $(e_1, \dots, e_n)$ we can always construct a (dual) basis $(e^1, \dots, e^n)$ for $X^{\vee}$ that satisfies $e^i(e_j) = \delta^i_j$. It follows that $V \approx V^{\vee}$ simply because they have the same finite dimension $n$. Now, it seems to me that we can construct an isomorphism by assigning $$ e_i \mapsto e^i $$ and extending by linearity. That is, for an arbitrary vector $v \in X$ given by $v = \sum v^ie_i$ we can specify a linear map   $$\phi:V \rightarrow V^{\vee}$$  by  $$ \phi(\sum v^ie_i) := \sum v^ie^i $$ It is a quick exercise to check that $\phi$ is an isomorphism. Now, although this construction seems correct, there is something that doesn't quite sit right with me about it. For one thing, there is no way to really make sense of the summation convention as the right side of the function will always contain two superscripts thus requiring an explicit summation sign. The other thing that feels rather off is actually taking a lower index and moving it to an upper index, i.e., $e_i \mapsto e^i$ (which, of course, is the reason that the summation convention doesn't work).  So, with this background my questions are   Is there any sense in which the above isomorphism is "favored" or "canonical"? Is there another way to construct an isomorphism between a vector space and its dual, that would "conserve indexes", for lack of a better way to state it. My guess here is that the answer is no but becomes possible if one assumes $V$ has an inner product. How to write startup script for Systemd? I have 2 graphics cards on my laptop. One is IGP and another discrete.   I've written a shell script to to turn off the discrete graphics card.  How can I convert it to systemd script to run it at start-up? difference between accuracy and Rand index (R) I'm very confused, when I read on the wikipedia "From a mathematical standpoint, Rand index is related to the accuracy, but is applicable even when class labels are not used."   and   But when I use in R the rand.index function from fossil package and the Accuracy function from MLmetrics it doesn't give the same answer  &gt; Accuracy(predicted, real) [1] 0.8266667  &gt; rand.index(predicted,real) [1] 0.7114989  Please can someone explain to me the difference between these two and which one should I use?  NB:I use the k-medoids clustering algorithm (function pam from cluster package) Say person A and person B are having a discussion/argument.   Person A tells person B that his views are arrogant, or closed-minded, or some other derogatory adjective. But in fact it is person A's views that are arrogant, closed-minded, etc. Person B's views are usually the exact opposite of what person A is accusing him of.  This sort of situation happens a lot when discussing politics or religion, for example.  What do you call person A, for calling person B something that he himself is?  I guess, for the most part, person A doesn't actually realize that he is the one that the adjective applies to, and not person B. Maybe there is a different name if person A knows the adjective also applies to him. How do we pass the field api name in lwc for a lightning data table? Time complexity of nested for-loop Negative logLikelihood Kalman filter apt-get autoremove wants to remove linux headers How to find users by name How to remove deleted chatroom from favorite rooms? Find the eigenvector associated with the smallest eigenvalue, not smallest in magnitude Is frequency quantized in the black body spectrum?