I would like to synchronize two Bash scripts via a file lock. How to do this? Zsh has zsystem flock call, but is there a more "shellish" method that's also available to Bash?
I have a bash script that makes a cURL request and writes the output to a file called resp.txt.  I need to create an exclusive lock so that I can write to that file and not worry about multiple users running the script and editing the text file at the same time. Here is the code that I expect to lock the file, perform the request, and write to the text file: ( flock -e 200 curl 'someurl' -H 'someHeader' &gt; resp.txt ) 200&gt;/home/user/ITS/resp.txt  Is this the correct way to go about this?  My actual script is a bit longer than this, but it seems to break when I add the flock syntax to the bash script. If someone could explain how these file descriptors work and let me know if I am locking the file correctly that would be awesome!
How do I get the full url of the page I am on in C# How to combine Bump Maps? I'm trying to add a bump map with logo to noise texture Bump map.  I have a bump map created with Noise texture and then on top of that I want to add my bump logo (which also has it's own color on it.)   Is it possible within one material? Combinatorics riddle: keys and a safe There are 8 crew members, The leading member wants that only a crew of 5 people or more could open a safe he bought, To each member he gave equal amount of keys, and locked the safe with several locks.  What's the minimal number of locks he should put:   at least 5 crew members would be required to open the safe? Any team of 5 crew members could open the safe, but none of the 4 team crew members.   1,2 stands individually of course. Money transfer from India to USA My daughter is a US Citizen. We (parents)are also planning to permanently settle in US. We will go their as Permanent Resident,as per US Law. We have a house here in India worth Rs.2 Crores.  We want to sell it and take money with us. We have ordinary savings Bank account here in India.  My US Citizen Daughter is a Income Tax payer.  Now your advises are required as under:   What are the routes to take money from India to US and our tax liabilities Can I gift this whole amount to my US Citizen Daughter or what is the maximum limit of Gift amount.  What will be the tax liability on me and on my Daughter in case of Gift   Whether I have to show it in my Income Tax Return or in my Daughter's Tax Return. What US Income Tax Laws says. What will be the procedure to send money as Gift to my Daughter. Will the money will go directly from my Bank Act.to my Daughter's Bank Account. Will there will be wire transfer from bank to bank Can I send money through other money sender Certified Companies also.    Please advise. If there is something more on the subject to make me understand, please advise. Thanks, SCJP6 regex issue What is the best way to clean the sensor on a interchangeable lens camera (mirrorless or digital SLR)? I've got a couple of spots of dust on the sensor of my Canon 20D. A rocket blower isn't shifting them, and I'm ridiculously scared of some of the more direct methods for cleaning sensors — what methods/systems have you tried, and how successful have they been? What are the eigenvalues of $\operatorname{ad}x$? Let $x\in \operatorname{gl}(n,F)$ have $n$ distinct eigenvalues $a_1,\ldots,a_n$ in $F$. Prove that the eigenvalues of $\text{ad }x$ are precisely the $n^2$ scalars $a_i-a_j$ ($1\leq i,j\leq n$), which of course need not be distinct.   So we can represent $x$ by an $n\times n$ matrix $X$. We have $Xv_1=a_1v_1,\ldots, Xv_n=a_nv_n$ for eigenvectors $v_1,\ldots,v_n$.   Now, $\operatorname{ad}x$ takes $y\in \operatorname{gl}(n,F)$ to $xy-yx$. I need to show that some $y$ is taken to a scalar multiple of itself, where that scalar is $a_i-a_j$. What could be that $y$? I wish to select areas of a mesh, but it would be much simpler to just select the ones I don't want selected (because they are easier to access), and then inverse the selection.  Is this possible? How Do I insert a image in LaTex from my computer How do I create a file in windows from where LaTex can extract the pdf or Jpg file I want to insert in my document? In other words I need an example of inserting either images or pdf files in my document Here's the image I want to insert    The Image will be placed center to the page just beneath this codes  \[ \overline \rho = \overline P + 0.645 \Big (\frac { \overline P}{K}\Big) ^{\frac {3}{4}} \tag { Tazkera} \] Font size setting is missed in iPhone application Can you add a setting for choosing font size in iPhone mobile app?   It's hard to read questions. Taylor Series type inequality Recently, I read in the journal  that Stephen Hawking wrote a paper claiming that black holes do not exist.  How is this possible? Please explain it to me because I didn't understand what he said.  References:   Article in Nature News:  (Zeeya Merali, January 24, 2014). S. Hawking, Information Preservation and Weather Forecasting for Black Holes, . Let $U,W$ be subspaces of a vector space $V$. Show that   $$\dim(U)+\dim(W)=\dim(U+W)+\dim(U\cap W)$$   Hint: Show that the map given by $L:U×W\to V$ given by $L(u,w)=u-w$ is linear.   I can show that $L:U×W\to V$ given by $L(u,w)=u-w$ is a linear map. I also know that the dimension of $U×W$ is $\dim(U)+\dim(W)$. What do I do next? Any hints? I was thinking along the lines of using typeid() but I don't know how to ask if that type is a subclass of another class (which, by the way, is abstract) Too many SE sites causes confusion have already been created through .  have already completed their beta stage and are waiting for launch.  are in public beta stage.  are in commitment phase in   proposals are listed in   Now it is really confusing to find a suitable site to ask a question. As an example - I host a blog using . Now I have a question about this hosting. I want to post it in a . Where will I post? I have 2 options available now.     Are developers trying anything to solve this confusing matter? I lost the sa password on a machine, and when I log in to the machine directly using an account in the admin group, SQL Server Management Studio will not allow me to log in using Windows authentication.  My plan was to simply log into the server, connect via Windows Authentication, and reset sa to use a new password. Since I cant' connect via Windows Authentication, this won't work.  How else can I reset the sa password? We need to prove that $$\dfrac{\sin\theta - \cos\theta + 1}{\sin\theta + \cos\theta - 1} = \frac 1{\sec\theta - \tan\theta}$$  I have tried and it gets confusing. Specific vocabulary for making someone laugh by rubbing their underarm with finger I know that there exists at least one solution, because $ax \equiv b \mod m \implies ax - b = qm$  Rearranging terms gives $ax - qm = b$, and since $d | a$ and $d | m$, so $d | b$ it can be said that $b \equiv 0 \mod d$.  I implemented Euclid's extended algorithm and have been able to experimentally verify that the claim holds, but I do not see a pattern or how I can begin to show there are exactly $d$ solutions.  def euclid_extended(x, y, i=0):   if y == 0:     print("iteration {0} returns ({1}, {2}, {3}) - base case hit with ({4}, {5})".format(i, x, 1, 0, x, y))     return (x, 1, 0)   else:     (d, a, b) = euclid_extended(y, x % y, i + 1)     print("iteration {0}. ({4}, {5}) =&gt; ({1}, {2}, {3})".format(i, d, b, a - b * (x//y), x, y))     return (d, b, a - b * (x//y)) How do I distinguish between a command, utility, or builtin for getting documentation?