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  • iPad / iPhone Sync (WLAN or Inet)

    - by tobi
    I have actually one app with a SQLite DB and i port this at the moment to the ipad. My idea is a sync between iPad and iPhone for one table... But the Problem is "Person A" edit/change, create or delete a data record on iphone and "Person B" make the same or delete the edited record from Person A on the same time. Has anybody a idea for this? Or a nice lib for this?

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  • local code files synch with server

    - by webdev
    I search for way to synch my local code with server on debain linux. For example i modify some files, then i can run synch command, and only changed files send to server (using ssh for ex). Can you help me with good light solution for this?

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  • Can Windows Mobile Synch Services use a business layer

    - by Andy Kakembo
    We're building a Win Mobile 6 warehouse app which needs to update our server based corporate DB. We've got a C# business layer that sits on our app server and we'd really like our warehouse app to go through this. We also like MS Synch Services. Is there a way to combine the two ie can we use sync services but get them to go through our business layer ? Has anyone done this and got an example I can follow ? Is there a best practice for this kind of scenario ? Thanks, Andy

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  • Linked list example using threads

    - by Carl_1789
    I have read the following code of using CRITICAL_SECTION when working with multiple threads to grow a linked list. what would be the main() part which uses two threads to add to linked list? #include <windows.h> typedef struct _Node { struct _Node *next; int data; } Node; typedef struct _List { Node *head; CRITICAL_SECTION critical_sec; } List; List *CreateList() { List *pList = (List*)malloc(sizeof(pList)); pList->head = NULL; InitializeCriticalSection(&pList->critical_sec); return pList; } void AddHead(List *pList, Node *node) { EnterCriticalSection(&pList->critical_sec); node->next = pList->head; pList->head = node; LeaveCriticalSection(&pList->critical_sec); } void Insert(List *pList, Node *afterNode, Node *newNode) { EnterCriticalSection(&pList->critical_sec); if (afterNode == NULL) { AddHead(pList, newNode); } else { newNode->next = afterNode->next; afterNode->next = newNode; } LeaveCriticalSection(&pList->critical_sec); } Node *Next(List *pList, Node *node) { Node* next; EnterCriticalSection(&pList->critical_sec); next = node->next; LeaveCriticalSection(&pList->critical_sec); return next; }

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  • Syncing magento database froms development to production

    - by ringerce
    I use git for version control. I have a development, staging and production environment. When I finish in development I push to staging for review by the client. When approved, I push changes from staging to production. That works fine as long as there is no database changes. What happens if I install modules via Magento connect on local development and it makes database modifications. How would I push those changes up to the production server since the production server is always changing? Edit: I wrote two shell scripts. One that pulls the production database down to my development server, replaces base url with develpment url and updates my development db accordingly. It also leaves the production sql dump behind to be added to my git repo. I'm not really sure if it's beneficial to keep the raw dumps in source control but I'm going to try it out. The second scripts moves the development database up to staging and essentially performs the same operations as the first. Now when it comes time to move to production I pull the updated production repo into the production server and allow magento to do it's thing. I also started using SQLYog recently and it has a database comparison wizard which will give me the differences in my development and production databases and allow me to merge the changes in selectively. It always creates a migration script that I added to source control as well. If anything goes wrong I can run the comparison to see if anything was missed. Does this sounds like a decent workflow to you guys?

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  • Synchronizing DataGridView (DataTable) with the DB

    - by Ezekiel Rage
    Hi! I have the following situation: there is a table in the DB that is queried when the form loads and the retrieved data is filled into a DataGridView via the DataTable underneath. After the data is loaded the user is free to modify the data (add / delete rows, modify entries). The form has 2 buttons: Apply and Refresh. The first one sends the changes to the database, the second one re-reads the data from the DB and erases any changes that have been made by the user. My question is: is this the best way to keep a DataGridView synchronized with the DB (from a users point of view)? For now these are the downsides: the user must keep track of what he is doing and must press the button every while the modifications are lost if the form is closed / app crash / ... I tried sending the changes to the DB on CellEndEdit event but then the user also needs some Undo/Redo functionality and that is ... well ... a different story. So, any suggestions?

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  • How do I make my ArrayList Thread-Safe? Another approach to problem in Java?

    - by thechiman
    I have an ArrayList that I want to use to hold RaceCar objects that extend the Thread class as soon as they are finished executing. A class, called Race, handles this ArrayList using a callback method that the RaceCar object calls when it is finished executing. The callback method, addFinisher(RaceCar finisher), adds the RaceCar object to the ArrayList. This is supposed to give the order in which the Threads finish executing. I know that ArrayList isn't synchronized and thus isn't thread-safe. I tried using the Collections.synchronizedCollection(c Collection) method by passing in a new ArrayList and assigning the returned Collection to an ArrayList. However, this gives me a compiler error: Race.java:41: incompatible types found : java.util.Collection required: java.util.ArrayList finishingOrder = Collections.synchronizedCollection(new ArrayList(numberOfRaceCars)); Here is the relevant code: public class Race implements RaceListener { private Thread[] racers; private ArrayList finishingOrder; //Make an ArrayList to hold RaceCar objects to determine winners finishingOrder = Collections.synchronizedCollection(new ArrayList(numberOfRaceCars)); //Fill array with RaceCar objects for(int i=0; i<numberOfRaceCars; i++) { racers[i] = new RaceCar(laps, inputs[i]); //Add this as a RaceListener to each RaceCar ((RaceCar) racers[i]).addRaceListener(this); } //Implement the one method in the RaceListener interface public void addFinisher(RaceCar finisher) { finishingOrder.add(finisher); } What I need to know is, am I using a correct approach and if not, what should I use to make my code thread-safe? Thanks for the help!

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  • Java threads not working correctly with linkedlist

    - by user69514
    Hi I am working on the sleeping barber problem. with the addition of having priority customer when they arrive they go in the front of the line and they are the next ones to get a haircut. I'm using a linkedlist and if I see a priority customer I put him in the beginning of the list, if the customer is not priority he goes to the end of the list. then I call the wantHaircut method getting the first element of the list. my problem is that the customer are being processed in the order they arrive, and the priority customer have to wait. here is the code where it all happens. any ideas what I am doing wrong? thanks public void arrivedBarbershop(Customer c){ if(waiting < numChairs && c.isPriority()){ System.out.println("Customer " + c.getID() + ": is a priority customer - SITTING -"); mutex.up(); customer_list.addFirst(c); } else if(waiting >= numChairs && c.isPriority()){ System.out.println("Customer " + c.getID() + ": is a priority customer - STANDING -"); mutex.up(); customer_list.addFirst(c); } else if(waiting < numChairs && !c.isPriority()){ waiting++; System.out.println("Customer " + c.getID() + ": arrived, sitting in the waiting room"); customer_list.addLast(c); customers.up(); // increment waiting customers } else if(waiting >= numChairs && !c.isPriority()) { System.out.println("Customer " + c.getID() + ": went to another barber because waiting room was full - " + waiting + " waiting"); mutex.up(); } if(!customer_list.isEmpty()){ this.wantHairCut(customer_list.removeFirst()); } } public void wantHairCut(Customer c) { mutex.up(); barber.down(); // waits for being allowed in barber chair System.out.println("Customer " + c.getID() + ": getting haircut"); try { /** haircut takes between 1 and 2 seconds **/ Thread.sleep(Barbershop.randomInt(1, 2) * 1000); } catch (InterruptedException e) { } System.out.println("Barber: finished cutting customer " + c.getID() + "'s hair"); c.gotHaircut = true; cutting.up(); // signals cutting has finished /** customer must pay now **/ this.wantToCashout(c); }

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  • Synchronizing in SQL Replication works when manually syncing, but not automatically

    - by Dominic Zukiewicz
    I'm using SQL Server 2005 to create a replication copy of the main databases, so that the reports can point to the replication copy instead of locking out our main databases. I have set up the 3 databases as publications and then 3 subscribers moving the transactions over to the subscribers, instantaneously I hope! What seems to be happening is that when using the "Insert Tracer" function, replication take publisher to distributor < 2 seconds, but to replicate to the subscribers can take over 7 minutes (and these are local databases on a SAN). This could be for 2 reasons: The SQL statements used to query the database are obtaining locks which are stopping the transactions updating the subscribers. The subscribers are just too busy for the replication to apply the changes. What seems to trouble me more, is that although the Replication Monitor / Insert Tracer are showing these statistics, if you use the "View Subscription Details" and then click Start, it will sync within seconds. My goal would be to have the data syncing (ideally) continuously, or every minute, perhaps I should reduce the batch size of the transactions? What am I doing wrong? [Note that the -Continuous flag is set!]

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  • How would you implement this "WorkerChain" functionality in .NET?

    - by Dan Tao
    Sorry for the vague question title -- not sure how to encapsulate what I'm asking below succinctly. (If someone with editing privileges can think of a more descriptive title, feel free to change it.) The behavior I need is this. I am envisioning a worker class that accepts a single delegate task in its constructor (for simplicity, I would make it immutable -- no more tasks can be added after instantiation). I'll call this task T. The class should have a simple method, something like GetToWork, that will exhibit this behavior: If the worker is not currently running T, then it will start doing so right now. If the worker is currently running T, then once it is finished, it will start T again immediately. GetToWork can be called any number of times while the worker is running T; the simple rule is that, during any execution of T, if GetToWork was called at least once, T will run again upon completion (and then if GetToWork is called while T is running that time, it will repeat itself again, etc.). Now, this is pretty straightforward with a boolean switch. But this class needs to be thread-safe, by which I mean, steps 1 and 2 above need to comprise atomic operations (at least I think they do). There is an added layer of complexity. I have need of a "worker chain" class that will consist of many of these workers linked together. As soon as the first worker completes, it essentially calls GetToWork on the worker after it; meanwhile, if its own GetToWork has been called, it restarts itself as well. Logically calling GetToWork on the chain is essentially the same as calling GetToWork on the first worker in the chain (I would fully intend that the chain's workers not be publicly accessible). One way to imagine how this hypothetical "worker chain" would behave is by comparing it to a team in a relay race. Suppose there are four runners, W1 through W4, and let the chain be called C. If I call C.StartWork(), what should happen is this: If W1 is at his starting point (i.e., doing nothing), he will start running towards W2. If W1 is already running towards W2 (i.e., executing his task), then once he reaches W2, he will signal to W2 to get started, immediately return to his starting point and, since StartWork has been called, start running towards W2 again. When W1 reaches W2's starting point, he'll immediately return to his own starting point. If W2 is just sitting around, he'll start running immediately towards W3. If W2 is already off running towards W3, then W2 will simply go again once he's reached W3 and returned to his starting point. The above is probably a little convoluted and written out poorly. But hopefully you get the basic idea. Obviously, these workers will be running on their own threads. Also, I guess it's possible this functionality already exists somewhere? If that's the case, definitely let me know!

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  • How to sync bookmarks across Google Chrome and Mozilla Firefox bookmarks?

    - by ViliusK
    How to sync bookmarks across Google Chrome and Mozilla Firefox bookmarks? As I, currently, understand, Google Chrome puts bookmarks seperatly from Google Bookmarks, which is accessible in Firefox by using Google Toolbar for Firefox. Right? So how should I synchronize my browsers? I use Google Chrome as my primary browser and it works good and bookmarks are synchronized across number of computers I'm using. Thanks, viliusk

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  • how many processors can I get in a block on cuda GPU?

    - by Vickey
    hi all, I have two questions to ask 1) If I create only one block of threads in cuda and execute the my parallel program on it then is it possible that more than one processors would be given to single block so that my program get some benefit of multiprocessor platform ? 2) can I synchronize the threads of different blocks ? if yes please give some hints. Thanks in advance since I know I'll get replies as always I get.

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  • Why AutoResetEvent and ManualResetEvent does not support name in the constructor?

    - by Ikaso
    On .NET Framework 2.0 AutoResetEvent and ManualResetEvent inherit from EventWaitHandle. The EventWaitHandle class has 4 different constructors. 3 of the constructors support giving a name to the event. On the other hand both ManualResetEvent and AutoResetEvent do not support naming and provide a single constructor that receives the initialState. I can simply inherit from EventWaitHandle and write my own implementation of those classes that support all the constructor overloads, but I don't like to re-invent the wheel if I do not have to. My questions are: Is there a special problem in naming events? Do you have any idea why Microsoft did not support it? Do you have a proposal better than inheriting from the EventWaitHandle class and calling the appropriate constructor as in the following example? public class MyAutoResetEvent: EventWaitHandle { public MyAutoResetEvent(bool initialState) : base(initialState, EventResetMode.AutoReset) { } public MyAutoResetEvent(bool initialState, string name) : base(initialState, EventResetMode.AutoReset, name) { } public MyAutoResetEvent(bool initialState, string name, out bool createdNew) : base(initialState, EventResetMode.AutoReset, name, out createdNew) { } public MyAutoResetEvent(bool initialState, string name, out bool createdNew, EventWaitHandleSecurity eventSecurity) : base(initialState, EventResetMode.AutoReset, string.Empty, out createdNew, eventSecurity) { } }

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  • Class initialization and synchronized class method

    - by nybon
    Hi there, In my application, there is a class like below: public class Client { public synchronized static print() { System.out.println("hello"); } static { doSomething(); // which will take some time to complete } } This class will be used in a multi thread environment, many threads may call the Client.print() method simultaneously. I wonder if there is any chance that thread-1 triggers the class initialization, and before the class initialization complete, thread-2 enters into print method and print out the "hello" string? I see this behavior in a production system (64 bit JVM + Windows 2008R2), however, I cannot reproduce this behavior with a simple program in any environments. In Java language spec, section 12.4.1 (http://java.sun.com/docs/books/jls/second_edition/html/execution.doc.html), it says: A class or interface type T will be initialized immediately before the first occurrence of any one of the following: T is a class and an instance of T is created. T is a class and a static method declared by T is invoked. A static field declared by T is assigned. A static field declared by T is used and the reference to the field is not a compile-time constant (§15.28). References to compile-time constants must be resolved at compile time to a copy of the compile-time constant value, so uses of such a field never cause initialization. According to this paragraph, the class initialization will take place before the invocation of the static method, however, it is not clear if the class initialization need to be completed before the invocation of the static method. JVM should mandate the completion of class initialization before entering its static method according to my intuition, and some of my experiment supports my guess. However, I did see the opposite behavior in another environment. Can someone shed me some light on this? Any help is appreciated, thanks.

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  • How to synchronize threads in python?

    - by Eric
    I have two threads in python (2.7). I start them at the beginning of my program. While they execute, my program reaches the end and exits, killing both of my threads before waiting for resolution. I'm trying to figure out how to wait for both threads to finish before exiting. def connect_cam(ip, execute_lock): try: conn = TelnetConnection.TelnetClient(ip) execute_lock.acquire() ExecuteUpdate(conn, ip) execute_lock.release() except ValueError: pass execute_lock = thread.allocate_lock() thread.start_new_thread(connect_cam, ( headset_ip, execute_lock ) ) thread.start_new_thread(connect_cam, ( handcam_ip, execute_lock ) ) In .NET I would use something like WaitAll() but I haven't found the equivalent in python. In my scenario, TelnetClient is a long operation which may result in a failure after a timeout.

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  • Efficient implementation of threads in the given scenario

    - by shadeMe
    I've got a winforms application that is set up in the following manner: 2 buttons, a textbox, a collection K, function X and another function, Y. Function X parses a large database and enumerates some of its data in the global collection. Button 1 calls function X. Function Y walks through the above collection and prints out the data in the textbox. Button 2 calls function Y. I'd like to call function X through a worker thread in such a way that: The form remains responsive to user input. This comes intrinsically from the use of a separate thread. There is never more than a single instance of function X running at any point in time. K can be accessed by both functions at all times. What would be the most efficient implementation of the above environment ?

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  • database synchronisation

    - by chetan
    hello friends, I have two databases at two different places, both databases are same with table name as well as fields. now I want to synchronise both database. Is there any java code or we can achieve that directly from mysql or sql ? How ?

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  • How do people handle foreign keys on clients when synchronizing to master db

    - by excsm
    Hi, I'm writing an application with offline support. i.e. browser/mobile clients sync commands to the master db every so often. I'm using uuid's on both client and server-side. When synching up to the server, the servre will return a map of local uuids (luid) to server uuids (suid). Upon receiving this map, clients updated their records suid attributes with the appropriate values. However, say a client record, e.g. a todo, has an attribute 'list_id' which holds the foreign key to the todos' list record. I use luids in foreign_keys on clients. However, when that attribute is sent over to the server, it would dirty the server db with luids rather than the suid the server is using. My current solution, is for the master server to keep a record of the mappings of luids to suids (per client id) and for each foreign key in a command, look up the suid for that particular client and use the suid instead. I'm wondering wether others have come across thus problem and if so how they have solved it? Is there a more efficient, simpler way? I took a look at this question "Synchronizing one or more databases with a master database - Foreign keys (5)" and someone seemed to suggest my current solution as one option, composite keys using suids and autoincrementing sequences and another option using -ve ids for client ids and then updating all negative ids with the suids. Both of these other options seem like a lot more work. Thanks, Saimon

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  • Why there is no scoped locks for multiple mutexes in C++0x or Boost.Thread?

    - by Vicente Botet Escriba
    C++0x thread library or Boost.thread define non-member variadic template function that lock all lock avoiding dead lock. template <class L1, class L2, class... L3> void lock(L1&, L2&, L3&...); While this function avoid help to deadlock, the standard do not includes the associated scoped lock to write exception safe code. { std::lock(l1,l2); // do some thing // unlock li l2 exception safe } That means that we need to use other mechanism as try-catch block to make exception safe code or define our own scoped lock on multiple mutexes ourselves or even do that { std::lock(l1,l2); std::unique_lock lk1(l1, std::adopted); std::unique_lock lk2(l2, std::adopted); // do some thing // unlock li l2 on destruction of lk1 lk2 } Why the standard doesn't includes a scoped lock on multiple mutexes of the same type, as for example { std::array_unique_lock<std::mutex> lk(l1,l2); // do some thing // unlock l1 l2 on destruction of lk } or tuples of mutexes { std::tuple_unique_lock<std::mutex, std::recursive_mutex> lk(l1,l2); // do some thing // unlock l1 l2 on destruction of lk } Is there something wrong on the design?

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  • Microsoft Sync Framework - How to reprovision a table (or entire scope) after schema changes?

    - by Rabbi
    I have already setup syncing with Microsoft Sync Framework, and now I need to add fields to a table. How do I re-provision the databases? The setup is exceedingly simple: Two SQL Express 2008 servers The scope includes the entire database Using Microsoft Sync Framework 2.0 Synchronizing by direct access. Using the standard new SqlSyncProvider Do I make the structural changes at both ends? Or do I only change one server and let Sync Framework somehow propagate the change? Do I need to delete the _tracking tables and/or the stored procedures? How about the triggers? Has anyone been using the Sync Framework? Please help.

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  • How to unit test synchronized code

    - by gillJ
    Hi, I am new to Java and junit. I have the following peice of code that I want to test. Would appreciate if you could send your ideas about what's the best way to go about testing it. Basically, the following code is about electing a leader form a Cluster. The leader holds a lock on the shared cache and services of the leader get resumed and disposed if it somehow looses the lock on the cache. How can i make sure that a leader/thread still holds the lock on the cache and that another thread cannot get its services resumed while the first is in execution? public interface ContinuousService { public void resume(); public void pause(); } public abstract class ClusterServiceManager { private volatile boolean leader = false; private volatile boolean electable = true; private List<ContinuousService> services; protected synchronized void onElected() { if (!leader) { for (ContinuousService service : services) { service.resume(); } leader = true; } } protected synchronized void onDeposed() { if (leader) { for (ContinuousService service : services) { service.pause(); } leader = false; } } public void setServices(List<ContinuousService> services) { this.services = services; } @ManagedAttribute public boolean isElectable() { return electable; } @ManagedAttribute public boolean isLeader() { return leader; } public class TangosolLeaderElector extends ClusterServiceManager implements Runnable { private static final Logger log = LoggerFactory.getLogger(TangosolLeaderElector.class); private String election; private long electionWaitTime= 5000L; private NamedCache cache; public void start() { log.info("Starting LeaderElector ({})",election); Thread t = new Thread(this, "LeaderElector ("+election+")"); t.setDaemon(true); t.start(); } public void run() { // Give the connection a chance to start itself up try { Thread.sleep(1000); } catch (InterruptedException e) {} boolean wasElectable = !isElectable(); while (true) { if (isElectable()) { if (!wasElectable) { log.info("Leadership requested on election: {}",election); wasElectable = isElectable(); } boolean elected = false; try { // Try and get the lock on the LeaderElectorCache for the current election if (!cache.lock(election, electionWaitTime)) { // We didn't get the lock. cycle round again. // This code to ensure we check the electable flag every now & then continue; } elected = true; log.info("Leadership taken on election: {}",election); onElected(); // Wait here until the services fail in some way. while (true) { try { Thread.sleep(electionWaitTime); } catch (InterruptedException e) {} if (!cache.lock(election, 0)) { log.warn("Cache lock no longer held for election: {}", election); break; } else if (!isElectable()) { log.warn("Node is no longer electable for election: {}", election); break; } // We're fine - loop round and go back to sleep. } } catch (Exception e) { if (log.isErrorEnabled()) { log.error("Leadership election " + election + " failed (try bfmq logs for details)", e); } } finally { if (elected) { cache.unlock(election); log.info("Leadership resigned on election: {}",election); onDeposed(); } // On deposition, do not try and get re-elected for at least the standard wait time. try { Thread.sleep(electionWaitTime); } catch (InterruptedException e) {} } } else { // Not electable - wait a bit and check again. if (wasElectable) { log.info("Leadership NOT requested on election ({}) - node not electable",election); wasElectable = isElectable(); } try { Thread.sleep(electionWaitTime); } catch (InterruptedException e) {} } } } public void setElection(String election) { this.election = election; } @ManagedAttribute public String getElection() { return election; } public void setNamedCache(NamedCache nc) { this.cache = nc; }

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  • Git repos over multiple machines - backups and keeping in sync

    - by a-or-b
    I'm new to git so please feel free to RTFM me... I have multiple development sites (none of which can communicate via a network with each other) and am working on a few projects (with a few people) at any one time. What I would ideally have is at each site a centralized repository that can be pulled from but development would occur in our own (personal) repos. Then I would like to be able to sync across the centralized repos (via USB key for example). I want a centralized repo at each location as (1) I'm new to git and do break my (personal) local repo by playing around and (2) some projects get put on hold so I want to be able to free up disk space by deleting them. This is the "backup" part of my question. I was also hoping to be able to use 'git clone --bare' for my centralized repos (and the USB key repos to?) as we don't need the full checkout, just the git benefits. However I can't seem to get a bare repo to work as repo I can push from. I've used 'git remote' to set up an remote origin (similar to http://toolmantim.com/thoughts/setting_up_a_new_remote_git_repository) but I can't get 'git push' to work - it seems I need a checked-out repo. . Does anyone else use this sort of repo/development structure or is there something fundamental about git usage that I'm missing? . A solution that I thought about that might not work - If I had a 'git clone --bare' at each site and then use a git repo on my removable media which has remotes set up for each site then I could ('pull') sync my USB key with each repo. But then can I update the site repo from my USB key? Could I push from USB?

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  • File synck tool with network support (FTP or SSH) and decent GUI

    - by Álvaro G. Vicario
    Is there a decent GUI tool for Windows that allows to publish files from/to a remote FTP (or SFTP) server with the same ease of use that WinMerge offers in local discs? I'll basically use it to upload changes to web sites. I've tried like a dozen tools and they're all terrible. They have difficult interfaces, you need to spend ten minutes configuring absurdly complicate project settings, there's no simple way to ignore specific files or they use custom databases that break when someone else uploads files—not to mention deployment frameworks that force you to script everything in their custom language. I don't need or even want to schedule or automate. I want a manual process I can review. I'm tired of picking files one by one in Filezilla while reading the Subversion logs. I'd love an open source tool but...

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