Search Results

Search found 13910 results on 557 pages for 'practical programming'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 155/557 | < Previous Page | 151 152 153 154 155 156 157 158 159 160 161 162  | Next Page >

  • Reference for proper handling of PID file on Unix

    - by bignose
    Where can I find a well-respected reference that details the proper handling of PID files on Unix? On Unix operating systems, it is common practice to “lock” a program (often a daemon) by use of a special lock file: the PID file. This is a file in a predictable location, often ‘/var/run/foo.pid’. The program is supposed to check when it starts up whether the PID file exists and, if the file does exist, exit with an error. So it's a kind of advisory, collaborative locking mechanism. The file contains a single line of text, being the numeric process ID (hence the name “PID file”) of the process that currently holds the lock; this allows an easy way to automate sending a signal to the process that holds the lock. What I can't find is a good reference on expected or “best practice” behaviour for handling PID files. There are various nuances: how to actually lock the file (don't bother? use the kernel? what about platform incompatibilities?), handling stale locks (silently delete them? when to check?), when exactly to acquire and release the lock, and so forth. Where can I find a respected, most-authoritative reference (ideally on the level of W. Richard Stevens) for this small topic?

    Read the article

  • Choosing a non microsoft language for web development?

    - by Luke Lowrey
    I am resonably experienced with asp.net and would like to learn a new language with a focus on web development. Licensing and hosting costs are why I would like to use something not reliant on microsoft so something based on open source technologies is a plus. I have had a tiny bit of experience with php and did not like it but I guess I could be convinced otherwise. Basically I'd like to know peoples opinion on the the best language for future web development with regards to longivity, resources, frameworks, hosting etc.

    Read the article

  • Bad File descriptor

    - by Luke
    Does anyone see a problem with this, its not working saying bad file descriptor not sure why? pipe(pipefd[0]); if ((opid = fork()) == 0) { dup2(pipefd[0][1],1);/*send to output*/ close(pipefd[0][0]); close(pipefd[0][1]); execlp("ls","ls","-al",NULL); } if((cpid = fork())==0){ dup2(pipefd[0][1],0);/*read from input*/ close(pipefd[0][0]); close(pipefd[1][1]); execlp("grep","grep",".bak",NULL); } close(pipefd[0][0]); close(pipefd[0][1]);

    Read the article

  • What are your recommended tools and frameworks for network development on Linux?

    - by Vivek Sharma
    What are your favourite network-tools, which you use to troubleshoot or design (as in conceptualize) your network-application code. Ethereal/Wireshark Nmap any particular simulators (e.g. ns) any special purpose sniffer any particular frameworks, (e.g. iptables) I am looking at must have, and good/advantage to have tools/framework in ones profile/skill set. I think Wireshark and Nmap are must haves.

    Read the article

  • Data Transfer Objects VS Domain/ActiveRecord Entities in the View in RoR

    - by leypascua
    I'm coming from a .NET background, where it is a practice to not bind domain/entity models directly to the view in not-so-basic CRUD-ish applications where the view does not directly project entity fields as-is. I'm wondering what's the practice in RoR, where the default persistence mechanism is ActiveRecord. I would assert that presentation-related info should not be leaked to the entities, not sure though if this is how real RoR heads would do it. If DTOs/model per view is the approach, how will you do it in Rails? Your thoughts? EDIT: Some examples: - A view shows a list of invoices, with the number of unique items in one column. - A list of credit card accounts, where possibly fraudulent transactions were executed. For that, the UI needs to show this row in red. For both scenarios, The lists don't show all of the fields of the entities, just a few to show in the list (like invoice #, transaction date, name of the account, the amount of the transaction) For the invoice example, The invoice entity doesn't have a field "No. of line items" mapped on it. The database has not been denormalized for perf reasons and it will be computed during query time using aggregate functions. For the credit card accounts example, surely the card transaction entity doesn't have a "Show-in-red" or "IsFraudulent" invariant. Yes it may be a business rule, but for this example, that is a presentation concern, so I would like to keep it out of my domain model.

    Read the article

  • The advantages and disadvantages of using ORM

    - by JHarley1
    Good Morning, I would like to discuss today the advantages and disadvantages of using ORM (such as ADO.NET). Advantages: Speeds-up Development - eliminates the need for repetitive SQL code. Reduces Development Time. Reduces Development Costs. Overcomes vendor specific SQL differences - the ORM knows how to write vendor specific SQL so you don't have to. Disadvantages: Loss in developer productivity whilst they learn to program with ORM. Developers loose understanding of what the code is actually doing - the developer is more in control using SQL. ORM has a tendency to be slow. ORM fail to compete against SQL queries for complex queries. In summary, I believe that the disadvantages of using an ORM (mainly the reduced time taken to perform repetitive tasks) is far outweighed by the disadvantages of ORM e.g. its difficulty to get to grips with. Can people point out were I am going wrong and suggest any further advantages/disadvantages. Many Thanks, J

    Read the article

  • How to solve a deallocated connection in iPhone SDK 3.1.3? - Streams - CFSockets

    - by Christian
    Hi everyone, Debugging my implementation I found a memory leak issue. I know where is the issue, I tried to solve it but sadly without success. I will try to explain you, maybe someone of you can help with this. First I have two classes involved in the issue, the publish class (where publishing the service and socket configuration is done) and the connection (where the socket binding and the streams configuration is done). The main issue is in the connection via native socket. In the 'publish' class the "server" accepts a connection with a callback. The callback has the native-socket information. Then, a connection with native-socket information is created. Next, the socket binding and the streams configuration is done. When those actions are successful the instance of the connection is saved in a mutable array. Thus, the connection is established. static void AcceptCallback(CFSocketRef socket, CFSocketCallBackType type, CFDataRef address, const void *data, void *info) { Publish *rePoint = (Publish *)info; if ( type != kCFSocketAcceptCallBack) { return; } CFSocketNativeHandle nativeSocketHandle = *((CFSocketNativeHandle *)data); NSLog(@"The AcceptCallback was called, a connection request arrived to the server"); [rePoint handleNewNativeSocket:nativeSocketHandle]; } - (void)handleNewNativeSocket:(CFSocketNativeHandle)nativeSocketHandle{ Connection *connection = [[[Connection alloc] initWithNativeSocketHandle:nativeSocketHandle] autorelease]; // Create the connection if (connection == nil) { close(nativeSocketHandle); return; } NSLog(@"The connection from the server was created now try to connect"); if ( ! [connection connect]) { [connection close]; return; } [clients addObject:connection]; //save the connection trying to avoid the deallocation } The next step is receive the information from the client, thus a read-stream callback is triggered with the information of the established connection. But when the callback-handler tries to use this connection the error occurs, it says that such connection is deallocated. The issue here is that I don't know where/when the connection is deallocated and how to know it. I am using the debugger, but after some trials, I don't see more info. void myReadStreamCallBack (CFReadStreamRef stream, CFStreamEventType eventType, void *info) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; Connection *handlerEv = [[(Connection *)info retain] autorelease]; // The error -[Connection retain]: message sent to deallocated instance 0x1f5ef0 (Where 0x1f5ef0 is the reference to the established connection) [handlerEv readStreamHandleEvent:stream andEvent:eventType]; [pool drain]; } void myWriteStreamCallBack (CFWriteStreamRef stream, CFStreamEventType eventType, void *info){ NSAutoreleasePool *p = [[NSAutoreleasePool alloc] init]; Connection *handlerEv = [[(Connection *)info retain] autorelease]; //Sometimes the error also happens here, I tried without the pool, but it doesn't help neither. [handlerEv writeStreamHandleEvent:eventType]; [p drain]; } Something strange is that when I run the debugger(with breakpoints) everything goes well, the connection is not deallocated and the callbacks work fine and the server is able to receive the message. I will appreciate any hint!

    Read the article

  • Linux Kernel - Red/Black Trees

    - by CodeRanger
    I'm trying to implement a red/black tree in Linux per task_struct using code from linux/rbtree.h. I can get a red/black tree inserting properly in a standalone space in the kernel such as a module but when I try to get the same code to function with the rb_root declared in either task_struct or task_struct-files_struct, I get a SEGFAULT everytime I try an insert. Here's some code: In task_struct I create a rb_root struct for my tree (not a pointer). In init_task.h, macro INIT_TASK(tsk), I set this equal to RB_ROOT. To do an insert, I use this code: rb_insert(&(current-fd_tree), &rbnode); This is where the issue occurs. My insert command is the standard insert that is documented in all RBTree documentation for the kernel: int my_insert(struct rb_root *root, struct mytype *data) { struct rb_node **new = &(root->rb_node), *parent = NULL; /* Figure out where to put new node */ while (*new) { struct mytype *this = container_of(*new, struct mytype, node); int result = strcmp(data->keystring, this->keystring); parent = *new; if (result < 0) new = &((*new)->rb_left); else if (result > 0) new = &((*new)->rb_right); else return FALSE; } /* Add new node and rebalance tree. */ rb_link_node(&data->node, parent, new); rb_insert_color(&data->node, root); return TRUE; } Is there something I'm missing? Some reason this would work fine if I made a tree root outside of task_struct? If I make rb_root inside of a module this insert works fine. But once I put the actual tree root in the task_struct or even in the task_struct-files_struct, I get a SEGFAULT. Can a root node not be added in these structs? Any tips are greatly appreciated. I've tried nearly everything I can think of.

    Read the article

  • Efficient Map Overlays in and drawing Lines on Android Google Map...

    - by Ahsan
    Hi Friends, I want to do the following and am kind of stuck on these for a few days.... 1) I have used helloItemizedOverlay to add about 150 markers and it gets very very slow.....any idea what to do ? I was thinking about threads....(handler) ... 2) I was trying to draw poly lines ( I have encoded polylines, but have managed to decoded those) that move when I move the map..... 3) I was looking for some sort of a timer class that executes, say, every 1 minute or so.... 4) I was also looking for ways to clear the Google map from all the markers/lines etc.... Thanks a lot... :) - ahsan

    Read the article

  • Filter items from a feed using words in a text file, with Yahoo Pipes

    - by pufferfish
    I have a pipe that filters an RSS feed and removes any item that contains "stopwords" that I've chosen. Currently I've manually created a filter for each stopword in the pipe editor, but the more logical way is to read these from a file. I've figured out how to read the stopwords out of the text file, but how do I apply the filter operator to the feed, once for every stopword? The documentation states explicitly that operators can't be applied within the loop construct, but hopefully I'm missing something here.

    Read the article

  • Auto switching databases from a rails app gracefully from the ApplicationController?

    - by Zaqintosh
    I've seen this post a few times, but haven't really found the answer to this specific question. I'd like to run a rails application that based on the detected request.host (imagine I have two subdomains points to the same rails app and server ip address: myapp1.domain.com and myapp2.domain.com). I'm trying to have myapp1 use the default "production" database, and myapp2 requests always use the alternative remote database. Here is an example of what I tried to do in Application controller that did not work: class ApplicationController < ActionController::Base helper :all before_filter :use_alternate_db private def use_alternate_db if request.host == 'myapp1.domain.com' regular_db elsif request.host == 'myapp2.domain.com' alternate_db end end def regular_db ActiveRecord::Base.establish_connection :production end def alternate_db ActiveRecord::Base.establish_connection( :adapter => 'mysql', :host => '...', :username => '...', :password => '...', :database => 'alternatedb' ) end end The problem is when it switches databases using this method, all connections (including valid sessions across the different subdomains get interrupted...). All examples online have people controlling database connectivity at the model level, but this would involve adding code all over my application. Is there some way to globally switch database connections on a per-request basis in the manner I'm suggesting above WITHOUT having to inject code all over my application? The added complexity here is I'm using Heroku as a hosting provider, so I have no control at the apache / rails application server level. I have looked at solutions like dbcharmer and magicmodels, but none seem to show examples of doing it in the manner that I'm trying to. Thanks for any help!

    Read the article

  • Receiving broadcast messages

    - by Prasad
    Hi, I'm trying to receive broadcast messages using C# code in an ISDN network with BRI interface at my end. I see the packets sent to the broadcast ip address (239.255.255.255) on some ports using Comm View tool. But when I try to listen to this IP address, it says the address is not in a valid context. But when I send broadcast messages to 255.255.255.255 on a port, I can receive those messages with the below code.. What could be the problem with this ip address - 239.255.255.255 ? The code I use to listen to broadcast messages is.. UdpClient udp = new UdpClient(); IPEndPoint receiveEndPoint = new IPEndPoint(IPAddress.Any, 8013); // If I use IPAddress.Parse("239.255.255.255") to listen to, // it says "the address is not in a valid // context." udp.Client.Bind(receiveEndPoint); udp.BeginReceive(_Callback, udp); static private void _Callback(IAsyncResult iar) { try { UdpClient client = (UdpClient)iar.AsyncState; client.BeginReceive(_Callback, client); IPEndPoint ipRemote = new IPEndPoint(IPAddress.Any, 8013); byte[] rgb = client.EndReceive(iar, ref ipRemote); Console.WriteLine("Received {0} bytes: \"{1}\"", rgb.Length.ToString(), Encoding.UTF8.GetString(rgb)); } catch (ObjectDisposedException) { Console.WriteLine("closing listening socket"); } catch (Exception exc) { Console.WriteLine("Listening socket error: \"" + exc.Message + "\""); } } There are packets sent to the broadcast ipaddress (239.255.255.255) which I can see in Commview tool, but can't receive them from the code... Can anybody help me out please? Thanking you in advance, Prasad Kancharla.

    Read the article

  • WebSocket for HTML5

    - by Sareuon
    Introduction: I am going to develop the instance messaging that is run on the browser. Problem: Unfortunately I can not find and no idea what are the browser that is support with web-socket. Question: What are the browser that support web-socket?

    Read the article

  • Storing VMware virtual machines in external harddisk

    - by Jeffery Ang
    Any issue with that? I recently setup ubunutu virtual machine on my external harddisk. Once i accidentally removed the external harddisk usb connection then when i try to startup the ubuntu virtual machine again i get kernel panic. I thinking of writing a cron script to backup everyday to another location to prevent this issue

    Read the article

  • shell script output in html + email that html

    - by Kimi
    Using Solaris I have a monitoring script that uses other scripts as plugins. Theses pugins are also scripts which work in difffernt ways like: 1. Sending an alert while high memory uilization 2. High Cpu usage 3. Full disk Space 4. chekcking the core file dump Now all this is dispalyed on my terminal and I want to put them in a HTML file/format and send it as a body of the mail not as attachment. Thanks .

    Read the article

  • OT: US Banks: Bank Routing Number and BIC/SWIFT

    - by Konerak
    I know it is a bit offtopic, but I've been having a hard time finding more information to this question, and since this site is visited by a lot of people from the United States, you guys might know/find the answer more easily. Banks in europe each have a SWIFT Number, while US Banks use Routing Numbers. This leads to following questions: Does each bank in the US also carry a BIC number? (SWIFT) Is there a 1-1 relationship between BIC and SWIFT? Is there a list of these numbers somewhere? (background information: we're adding international payments to our bookkeeping application. Users can add international suppliers, but my boss prefered not to change the current supplier table but to have the ROUTING NUMBER in another table, with as PK the BIC. I'm wondering if BIC is a valid choice, or if it should just be BANK ACCOUNT NUMBER.)

    Read the article

  • Linq Query Performance , comparing Compiled query vs Non-Compiled.

    - by AG.
    Hello Guys, I was wondering if i extract the common where clause query into a common expression would it make my query much faster, if i have say something like 10 linq queries on a collection with exact same 1st part of the where clause. I have done a small example to explain a bit more . public class Person { public string First { get; set; } public string Last { get; set; } public int Age { get; set; } public String Born { get; set; } public string Living { get; set; } } public sealed class PersonDetails : List<Person> { } PersonDetails d = new PersonDetails(); d.Add(new Person() {Age = 29, Born = "Timbuk Tu", First = "Joe", Last = "Bloggs", Living = "London"}); d.Add(new Person() { Age = 29, Born = "Timbuk Tu", First = "Foo", Last = "Bar", Living = "NewYork" }); Expression<Func<Person, bool>> exp = (a) => a.Age == 29; Func<Person, bool> commonQuery = exp.Compile(); var lx = from y in d where commonQuery.Invoke(y) && y.Living == "London" select y; var bx = from y in d where y.Age == 29 && y.Living == "NewYork" select y; Console.WriteLine("All Details {0}, {1}, {2}, {3}, {4}", lx.Single().Age, lx.Single().First , lx.Single().Last, lx.Single().Living, lx.Single().Born ); Console.WriteLine("All Details {0}, {1}, {2}, {3}, {4}", bx.Single().Age, bx.Single().First, bx.Single().Last, bx.Single().Living, bx.Single().Born); So can some of the guru's here give me some advice if it would be a good practice to write query like var lx = "Linq Expression " or var bx = "Linq Expression" ? Any inputs would be highly appreciated. Thanks, AG

    Read the article

  • Managing Cisco programatically; Telnet vs SNMP?

    - by MikeHerrera
    I was recently approached by a network-engineer, co-worker who would like to offload his minor network admin duties to a junior-level helpdesk tech. The specific location in need of management acts as an ISP for tenants on its single-site property, so there's a lot of small adjustments being made on a daily basis. I am thinking it would be helpful to write him a winform app to manage the 32 Cisco devices, on-site. I'd like to initially provide functionality which could modify access control lists, port VLAN assignments, and bandwidth limitations per VLAN... adding more to the list as its deemed valuable. My initial thought was to emulate a telnet session with the network device; utilizing my network-engineer's familiarity with the command-line / IOS interaction. Minimal time would be required to learn Cisco IOS conventions, myself. Though while searching for solutions, it appears that most people favor SNMP. That, or, their specific circumstances pushed them in the direction of SNMP. I wanted to know if I've overlooked an obvious benefit of SNMP. Should I be using SNMP? Why or why not?

    Read the article

  • Compiling Visual c++ programs from the command line and msvcr90.dll

    - by Stanley kelly
    Hi, When I compile my Visual c++ 2008 express program from inside the IDE and redistribute it on another computer, It starts up fine without any dll dependencies that I haven't accounted for. When I compile the same program from the visual c++ 2008 command line under the start menu and redistribute it to the other computer, it looks for msvcr90.dll at start-up. Here is how it is compiled from the command line cl /Fomain.obj /c main.cpp /nologo -O2 -DNDEBUG /MD /ID:(list of include directories) link /nologo /SUBSYSTEM:WINDOWS /ENTRY:mainCRTStartup /OUT:Build\myprogram.ex e /LIBPATH:D:\libs (list of libraries) and here is how the IDE builds it based on the relevant parts of the build log. /O2 /Oi /GL /I clude" /I (list of includes) /D "WIN32" /D "NDEBUG" /D "_CONSOLE" /D "_UNICODE" /D "UNICODE" /FD /EHsc /MD /Gy /Yu"stdafx.h" /Fp"Release\myprogram" /Fo"Release\\" /Fd"Release\vc90.pdb" /W3 /c /Zi /TP /wd4250 /vd2 Creating command line "cl.exe @d:\myprogram\Release\RSP00000118003188.rsp /nologo /errorReport:prompt" /OUT:"D:\myprgram\Release\myprgram.exe" /INCREMENTAL:NO /LIBPATH:"d:\gtkmm\lib" /MANIFEST /MANIFESTFILE:"Release\myprogam.exe.intermediate.manifest" /MANIFESTUAC:"level='asInvoker' uiAccess='false'" /DEBUG /PDB:"d:\myprogram\Release\myprogram.pdb" /SUBSYSTEM:WINDOWS /OPT:REF /OPT:ICF /LTCG /ENTRY:"mainCRTStartup" /DYNAMICBASE /NXCOMPAT /MACHINE:X86 (list of libraries) Creating command line "link.exe @d:\myprogram\Release\RSP00000218003188.rsp /NOLOGO /ERRORREPORT:PROMPT" /outputresource:"..\Release\myprogram.exe;#1" /manifest .\Release\myprogram.exe.intermediate.manifest Creating command line "mt.exe @d:\myprogram\Release\RSP00000318003188.rsp /nologo" I would like to be able to compile it from the command line and not have it look for such a late version of the runtime dll, like the version compiled from the IDE seems not to do. Both versions pass /MD to the compiler, so i am not sure what to do.

    Read the article

  • perl multiple tasks problem

    - by Alice Wozownik
    I have finished my earlier multithreaded program that uses perl threads and it works on my system. The problem is that on some systems that it needs to run on, thread support is not compiled into perl and I cannot install additional packages. I therefore need to use something other than threads, and I am moving my code to using fork(). This works on my windows system in starting the subtasks. A few problems: How to determine when the child process exits? I created new threads when the thread count was below a certain value, I need to keep track of how many threads are running. For processes, how do I know when one exits so I can keep track of how many exist at the time, incrementing a counter when one is created and decrementing when one exits? Is file I/O using handles obtained with OPEN when opened by the parent process safe in the child process? I need to append to a file for each of the child processes, is this safe on unix as well. Is there any alternative to fork and threads? I tried use Parallel::ForkManager, but that isn't installed on my system (use Parallel::ForkManager; gave an error) and I absolutely require that my perl script work on all unix/windows systems without installing any additional modules.

    Read the article

  • touchesBegin & touchesMove Xcode Obj C Question

    - by AndrewDK
    So I have my app working good when you press and drag along. I also have UIButtons set to Touch Down in Interface Builder. As well when you drag you need to drag from the outside of the UIButton. You cannot click on the UIButton and drag to the other. TOUCHES MOVED: Code: -(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [[event touchesForView:self.view] anyObject]; CGPoint location = [touch locationInView:touch.view]; if(CGRectContainsPoint(oneButton.frame, location)) { if (!oneButton.isHighlighted){ [self oneFunction]; [oneButton setHighlighted:YES]; } }else { [oneButton setHighlighted:NO]; } // if(CGRectContainsPoint(twoButton.frame, location)) { if (!twoButton.isHighlighted){ [self twoFunction]; [twoButton setHighlighted:YES]; } }else { [twoButton setHighlighted:NO]; } } TOUCHES BEGAN: Code: - (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [[event touchesForView:self.view] anyObject]; CGPoint location = [touch locationInView:touch.view]; if(CGRectContainsPoint(oneButton.frame, location)) { [self oneFunction]; [oneButton setHighlighted:YES]; } if(CGRectContainsPoint(twoButton.frame, location)) { [self twoFunction]; [twoButton setHighlighted:YES]; } } I want to be able to click on any of the button fire the function & also be able to drag from one button on to the other and fire that function. So basically just being able to click on a button and slide your finger over and activate the other button without having to press and slide from outside of the button. I think I'm close, need a bit of help. Hope thats clear enough. Thanks.

    Read the article

  • Yahoo Pipes: filter items in a feed based on words in a text file

    - by pufferfish
    I have a pipe that filters an RSS feed and removes any item that contains "stopwords" that I've chosen. Currently I've manually created a filter for each stopword in the pipe editor, but the more logical way is to read these from a file. I've figured out how to read the stopwords out of the text file, but how do I apply the filter operator to the feed, once for every stopword? The documentation states explicitly that operators can't be applied within the loop construct, but hopefully I'm missing something here.

    Read the article

  • A/UX cc compiler errors on trivial code: "declared argument argc is missing"

    - by Fzn
    On a quite ancient UNIX (Apple A/UX 3.0.1 for 680x0 processors) using the built-in c compiler (cc), this issue arrises. Here is the code I'm trying to compile: #include <stdlib.h> #include <stdio.h> int main() int argc; char **argv; { if (argc > 1) puts(argv[1]); return (EXIT_SUCCESS); } And here is the output I get: pigeonz.root # cc -c test.c "test.c", line 5: declared argument argc is missing "test.c", line 6: declared argument argv is missing Using a more modern prototype did not help, nor did the manual page, nor a quick google search. What am I doing wrong?

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 151 152 153 154 155 156 157 158 159 160 161 162  | Next Page >