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  • What to do if exec() fails?

    - by Grigory
    Let's suppose we have a code doing something like this: int pipes[2]; pipe(pipes); pid_t p = fork(); if(0 == p) { dup2(pipes[1], STDOUT_FILENO); execv("/path/to/my/program", NULL); ... } else { //... parent process stuff } As you can see, it's creating a pipe, forking and using the pipe to read the child's output (I can't use popen here, because I also need the PID of the child process for other purposes). Question is, what should happen if in the above code, execv fails? Should I call exit() or abort()? As far as I know, those functions close the open file descriptors. Since fork-ed process inherits the parent's file descriptors, does it mean that the file descriptors used by the parent process will become unusable?

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  • Magento layout related basic Questions ?

    - by user197992
    Here is what I think about Magento (plz correct me if I am wrong ) 1)Each module has its own layout.xml stored in /interface/theme/layouts/ folder. 2)Magento loads all these layouts for current theme and creates a big xml file. Now what I am confused at . a)If magento loads /default/default/ (interface & theme) then why all the templates & layouts are inside base/default/ ?? b)what if I create my module name “page” inside my namespace “Jason” i.e Jason_Page , now what will happen to blocks in layout files which are named c)Since all the layouts are loaded and merged into one big xml file , then what happen to all those reference blocks which have same name attribute and are inside “Default” handle tag ? e.g d)what is Local.xml layout for and its use ?? e)wats the relation ship between a module name foo , and its layout name foo.xml ? What will happen to layout.xml if two modules with same name exist in diff namespace ? Thanks in advance .

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  • Basic HTML Internal Link not working in IE8

    - by Eamonn
    This one has me scratching my head. I have a page with several internal links bringing the user down the page to further content. Beneath various sections there are further internal links bringing the user back to the top. This works fine in all browsers apart from IE8 (actual IE8 - not IE9 in IE8 mode) where they work go down, but not coming back up! Examples: <a href="page.php?v=35&amp;u=admin-videos#a">A &ndash; General</a> .... //travelling DOWN the page <h3><strong>A &ndash; General<a name="a"></a></strong></h3> <a name="top"></a> .... //travelling back up <a href="page.php?v=35&amp;u=admin-videos#top">Back to top.</a> I've tried filling the 'top' anchor with &nbsp; but that hasn't changed it. Any ideas? Actual use case: http://databizsolutions.ie/contents/page.php?v=35&u=admin-videos

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  • Error compiling basic java code

    - by Michael Younani
    New to java. Practicing coding by following a book. Heres my code: class Motorcycle { //Three instance variables - make and color are strings. while a boolean refers to TRUE OR FLASE(in this case off or on) String make; String color; boolean engineState; void startEngine() { if (engineState == true) System.out.print("The engine is already on."); else { engineState = true; System.out.print("The engine is now on."); } void showAtts() { System.out.print("This motorcycle is a " + color + " " + make); if (engineState ==true) System.out.print("The engine is on."); else System.out.print("The engine is off."); } } } When I compile I get 2 errors: 1) illegal start of expression 2) ; expected I can't pin point the problem. If anyone can direct me or hint me please do.

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  • Are there any platforms where using structure copy on an fd_set (for select() or pselect()) causes p

    - by Jonathan Leffler
    The select() and pselect() system calls modify their arguments (the 'struct fd_set *' arguments), so the input value tells the system which file descriptors to check and the return values tell the programmer which file descriptors are currently usable. If you are going to call them repeatedly for the same set of file descriptors, you need to ensure that you have a fresh copy of the descriptors for each call. The obvious way to do that is to use a structure copy: struct fd_set ref_set_rd; struct fd_set ref_set_wr; struct fd_set ref_set_er; ... ...code to set the reference fd_set_xx values... ... while (!done) { struct fd_set act_set_rd = ref_set_rd; struct fd_set act_set_wr = ref_set_wr; struct fd_set act_set_er = ref_set_er; int bits_set = select(max_fd, &act_set_rd, &act_set_wr, &act_set_er, &timeout); if (bits_set > 0) { ...process the output values of act_set_xx... } } My question: Are there any platforms where it is not safe to do a structure copy of the struct fd_set values as shown? I'm concerned lest there be hidden memory allocation or anything unexpected like that. (There are macros/functions FD_SET(), FD_CLR(), FD_ZERO() and FD_ISSET() to mask the internals from the application.) I can see that MacOS X (Darwin) is safe; other BSD-based systems are likely to be safe, therefore. You can help by documenting other systems that you know are safe in your answers. (I do have minor concerns about how well the struct fd_set would work with more than 8192 open file descriptors - the default maximum number of open files is only 256, but the maximum number is 'unlimited'. Also, since the structures are 1 KB, the copying code is not dreadfully efficient, but then running through a list of file descriptors to recreate the input mask on each cycle is not necessarily efficient either. Maybe you can't do select() when you have that many file descriptors open, though that is when you are most likely to need the functionality.) There's a related SO question - asking about 'poll() vs select()' which addresses a different set of issues from this question.

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  • C++ - Basic WinAPI question

    - by HardCoder1986
    Hello! I am now working on a some sort of a game engine and I had an idea to put everything engine-related into a static library and then link it to my actual problem. Right now I achieved it and actually link that library and every functions seem to work fine, except those, which are windows-related. I have a chunk of code in my library that looks like this: hWnd = CreateWindow(className, "Name", WS_OVERLAPPED | WS_CAPTION | WS_EX_TOPMOST, 0, 0, 800, 600, NULL, NULL, GetModuleHandle(NULL), this); if (hWnd) { ShowWindow(hWnd, SW_NORMAL); UpdateWindow(hWnd); } else { MessageBox(NULL, "Internal program error", "Error", MB_OK | MB_ICONERROR); return; } When this code was not in the library, but in the actual project, it worked fine, created the window and everything was ok. Right now (when I'm linking to my library that contains this code) CreateWindow(...) call returns NULL and GetLastError() returns "Operation succesfully completed" (wtf?). Could anybody help me with this? Is it possible to create a window and display it using a static library call and why could my code fail? Thank you.

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  • How to Implement Web Based Find File Database Via Text Search

    - by neversaint
    I have series of files like this: foo1.txt.gz foo2.txt.gz bar1.txt.gz ..etc.. and a tabular format file that describe those files: foo1 - Explain foo1 foo2 - Explain foo2 bar1 - Explain bar1 ..etc.. What I want to do is to have a website with a simple search bar and allow people to type foo1 or just foo and finally return the gzipped file(s) and the related explanation of the file(s). What's the best way to implement this and what kind of tools should I use. Sorry I am totally new in this area.

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  • What's wrong with this statement in perl?

    - by benjamin button
    print "$_", join(',',sort keys %$h),"\n"; It's giving me an error below: Use of uninitialized value in string at missing_months.pl line 36. 1,10,11,12 this print statement is present in a for loop as below: foreach my $num ( sort keys %hash ) { my $h = $hash{$num}; print "$_", join(',',sort keys %$h),"\n"; }

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  • Need help with basic optimization problem

    - by ??iu
    I know little of optimization problems, so hopefully this will be didactic for me: rotors = [1, 2, 3, 4...] widgets = ['a', 'b', 'c', 'd' ...] assert len(rotors) == len(widgets) part_values = [ (1, 'a', 34), (1, 'b', 26), (1, 'c', 11), (1, 'd', 8), (2, 'a', 5), (2, 'b', 17), .... ] Given a fixed number of widgets and a fixed number of rotors, how can you get a series of widget-rotor pairs that maximizes the total value where each widget and rotor can only be used once?

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  • join 3 files by first Column with awk ?

    - by noinflection
    i have three similar files, they are all like this: File A ID1 Value1a ID2 Value2a . . . IDN Value2n and i want an output like this Output ID1 Value1a Value1b Value1c ID2 Value2a Value2b Value2c ..... IDN ValueNa ValueNb ValueNc Looking to the first line, i want value1A to be the value of id1 in fileA, value1B the value of id1 in fileB, and so on which each field and each line. I thougth it like a sql join. I've tried several things but none of them where even close.

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  • A basic animation not showing up

    - by Rilakkuma
    I still try different basics with android, and now I'm stuck with animation. I'm trying to implement a simple animation. I've defined animation in xml file like this: alpha android:interpolator="@android:anim/accelerate_interpolator" android:fromAlpha="0.0" android:toAlpha="1.0" duration="3000" repeatCount="infinite" In my main view group I have an ImageView defined like this: <ImageView android:id="@+id/someb" android:src="@drawable/earth_normal" android:layout_width="wrap_content" android:layout_height="wrap_content" android:padding="5dip"/> And this is from my starting activity class: public class Ohayou extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ImageView earth = (ImageView)findViewById(R.id.someb); Animation earthFadeInAnimation = AnimationUtils.loadAnimation(this, R.anim.fade_in); earth.startAnimation(earthFadeInAnimation); } It finds ImageView successfuly and creates animation. but when I start emulator ImageView just shows the original src image, not an animation. What am I doing wrong? Thanks

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  • phpMyAdmin Cron to Delete Temporary Files

    - by JoeC
    I have a folder on my hosting which I periodically upload something to - /public_html/uploads - and I'd like to set up a cronjob through phpMyAdmin to empty it out on a regular basis. The current cron I have in pMA is find /public_html/uploads -maxdepth 1 -ctime 1 -exec rm -f {} \; (Ignore the fact that it's running every minute for now, it's so I can test it :) ) I know very little about what this command is actually doing, but it looks like "not very much". Can anyone help me fix it? :) Thanks.

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  • Finding the Largest and Smallest Integers In A Set- Basic

    - by Ka112324
    I'm kind of on the right track, however my output is not quite right. The program asks for the number of integers you have and then it asks for those numbers. For an example is says please enter the number of integers, you can put 3. And then you enter 3 numbers. I can't use arrays because I am a beginner student and we have not learned those yet. Using count is the only way that allows me to input integers. What do I need to add to my program? Again I am a general computer science student so I can't use anything advanced. I used include iostream, namespace int main and all that you just cant see it int data; int num; int count=0; int max=0; do { cout<<"Enter the number of intergers"<<endl; cin>>num; while (count<num) { cout<<"Please enter a number"<<endl; cin>>data; count++; if (data<min) { min=data; } if (data>max) { max=data; } } cout<<"Smallest integer:"<<min<<endl; cout<<"Largest integer:"<<max<<endl; cout<<"Would you like to continue?"<<endl; cin>>ans; } while ((ans=='y')||(ans=='Y')); return 0; }

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  • How do I use Perl to parse the output of the sqlplus command?

    - by benjamin button
    I have an SQL file which will give me an output like below: 10|1 10|2 10|3 11|2 11|4 . . . I am using this in a Perl script like below: my @tmp_cycledef = `sqlplus -s $connstr \@DLCycleState.sql`; after this above statement, since @tmp_cycledef has all the output of the SQL query, I want to show the output as: 10 1,2,3 11 2,4 How could I do this using Perl?

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  • Problem with basic program using Boost Threads in c++

    - by Eternal Learner
    I have a simple program which creates and executes as thread using boost threads in c++. #include<boost/thread/thread.hpp> #include<iostream> void hello() { std::cout<<"Hello, i am a thread"<<std::endl; } int main() { boost::thread th1(&hello); th1.join(); } The compiler throws an error against the th1.join() line. It says " Multiple markers at this line - undefined reference to `boost::thread::join()' - undefined reference to `boost::thread::~thread()' "

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  • Basic user authentication with records in AngularFire

    - by ajkochanowicz
    Having spent literally days trying the different, various recommended ways to do this, I've landed on what I think is the most simple and promising. Also thanks to the kind gents from this SO question: Get the index ID of an item in Firebase AngularFire Curent setup Users can log in with email and social networks, so when they create a record, it saves the userId as a sort of foreign key. Good so far. But I want to create a rule so twitter2934392 cannot read facebook63203497's records. Off to the security panel Match the IDs on the backend Unfortunately, the docs are inconsistent with the method from is firebase user id unique per provider (facebook, twitter, password) which suggest appending the social network to the ID. The docs expect you to create a different rule for each of the login method's ids. Why anyone using 1 login method would want to do that is beyond me. (From: https://www.firebase.com/docs/security/rule-expressions/auth.html) So I'll try to match the concatenated auth.provider with auth.id to the record in userId for the respective registry item. According to the API, this should be as easy as In my case using $registry instead of $user of course. { "rules": { ".read": true, ".write": true, "registry": { "$registry": { ".read": "$registry == auth.id" } } } } But that won't work, because (see the first image above), AngularFire sets each record under an index value. In the image above, it's 0. Here's where things get complicated. Also, I can't test anything in the simulator, as I cannot edit {some: 'json'} To even authenticate. The input box rejects any input. My best guess is the following. { "rules": { ".write": true, "registry": { "$registry": { ".read": "data.child('userId').val() == (auth.provider + auth.id)" } } } } Which both throws authentication errors and simultaneously grants full read access to all users. I'm losing my mind. What am I supposed to do here?

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  • Drupal Multisite - Subdirectory, Shared Hosting

    - by derekerdmann
    I'm trying to set up Drupal multisite in a shared hosting environment. The main site's location looks like http://www.mysite.com/foo/bar/ and my goal is to create another site using the same database at http://www.mysite.com/foo/bar/drupal2. I've created a new folder in the sites directory called www.mysite.com.foo.bar.drupal2 and added the default.settings.php and settings.php files, configured correctly for the environment, and I've set up a symlink from the main site's root to the subdirectory, with this command: ln -s . drupal2 The problem is that when I go to http://www.mysite.com/foo/bar/drupal2, I just get the main site at http://www.mysite.com without triggering the installer. What do I need to change to get the multisite working?

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  • Basic SWIG C++ use for Java

    - by duckworthd
    I've programmed a couple years in both C++ and Java, but I've finally come to a point where I need to bring a little unification between the two -- ideally, using SWIG. I've written a tiny and fairly pointless little class called Example: #include <stdio.h> class Example { public: Example(); ~Example(); int test(); }; #include "example.h" Example::Example() { printf("Example constructor called\n"); } Example::~Example() { printf("Example destructor called\n"); } int Example::test() { printf("Holy sh*t, I work!\n"); return 42; } And a corresponding interface file: /* File: example.i */ %module test %{ #include "example.h" %} %include "example.h" Now I have questions. Firstly, when I want to actually run SWIG initially, am I supposed to use the example_wrap.c (from swig -java example.i) or example_wrap.cxx (from swig -c++ example.i) file when recompiling with my original example.cpp? Or perhaps both? I tried both and the latter seemed most likely, but when I recompile as so: g++ example.cpp example_wrap.cxx -I/usr/lib/jvm/java-6-sun-.../include/ I get a host of errors regarding TcL of all things, asking me for the tcl.h header. I can't even wrap my mind around why it wants that much less needs it, and as such have found myself where I don't even know how to begin using SWIG.

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  • Basic Python While loop compound conditional evaluation

    - by dbjohn
    In Python IDLE Shell it seems I cannot use a compound conditional expression and a while loop. I tried it within brackets too. k=0 m=0 while k<10 & m<10: print k k +=1 m+=1 If I write while k<10: print k k+=1 This does work. Is there a way I could achieve the first block of code with the "and" operator. I have done it in Java. Do I just need to put together "if" statements to achieve the same functionality in Python?

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  • Getting value of specific item in combobox in Visual Basic 2013

    - by JaceG
    I'm having great difficulty trying to find how to simply get the text of one specific item in a ComboBox. I have cmbSelectedHinge as a dropdownlist style. All I need is to know what the text is in position 0. I would have thought simply: MsgBox(cmbSelectHinge.Items.IndexOf(0)) but no. It returns "-1" even though there is a line of text in it. It seems this question has never before been asked on the internet, and there's no useful information on MSDN. Any help, please

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  • Shell script exiting the loop after calling another script

    - by Johnyy
    Hi Guys, I have a shell script s1 calling another script s2 in a loop. However s1 can not seem to continue the loop after s2 returns. Commenting out the line that calls s2 will enable the loop to continue. s2 does copy of one file, s1 checks conditions and copy several files using s2. Can anyone give a pointer what is going on here? ... while read line s2 param1 param2 param3 echo "copy done" done < $tempfile echo "out of loop" ... "copy done" is printed, so is "out of loop"

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