I want to store gigabytes of media locally - and have them automatically removed when the app is uninstalled. I found this question, but it requires the qt library, and only stores app settings.
I'm guessing there's a convention followed across Windows, Mac and Linux. Are there any std helpers - or the like - for storing app data, cross-platform.
If not, is there a convention for the paths would I need to store these in, on each platform? I plan on creating an installer for each operating system, so it would be useful to know these paths so I can install my other data here.
I want to store gigabytes of media locally - and have them automatically removed when the app is uninstalled.
The average but skilled user is capable of copying the media elsewhere and would backup his disk regularly.
However, most C++ programs have a main accepting program arguments, and you could conventionally provide program arguments to remove the data. Be sure to properly document your design.
See this answer. On Unix or POSIX systems (Linux, MacOSX, FreeBSD....), you might accept a --clean-all-the-mess program option.
I'm guessing there's a convention followed across Windows, Mac and Linux.
As far as I know, this guess is wrong. (things are much more complex)
More generally, read about package managers. There are many of them. See guix for an interesting example. Debian and Fedora have different ones. Look into GNU stow and autoconf.
You could want to use a database, perhaps SQLite or PostGreSQL.
On Linux, see also Advanced Linux Programming then syscalls(2) and more about systemd.
On Windows, read about the WinAPI.
Is there a convention for the paths would I need to store these
Linux has hier(7) but some Linux distributions (including Android) don't follow that.
My recommendation: study the C++ code of some open source software close to your goals. You could find some of them on github or gitlab or SoftwareHeritage. See also POCO.
"Application Uninstall" event is visible to the OS, so your best bet is on finding some OS-specific hooks to register your call-backs to remove your local files yourself.
EDIT:
C++ STL is a piece of code (library) to write applications that run on top of some OS, so STL is not the place to look for application install/uninstall events, that are OS-level events. But nothing prevents you from writing an Uninstaller application for any OS. The question is who or how and when it will be executed.
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For a few years I was writing programs in Visual Studio for Windows and with GCC (Code Blocks) for Linux. Most of my libs compiled seamlessly as they worked both in Windows and Linux. However at the moment I am a bit confused, as I have to create an app using Cygwin. I don't really understand if I am still in UNIX/Linux environment, just running app on Windows by some "emulation", or I am rather on Windows just having access to some Linux/Unix functionality. From what I understood from the FAQ's and documentation it looks like I just should behave like in Linux environment.
All explanations I found in internet usually are very general and don't explain the detailed differences from programmers viewpoint.
Short question: Can I just write programs like I did for Linux without any major changes when using Cygwin?
Maybe.
A lot of code written for Linux will compile in Cygwin with very few problems, which can mainly be fixed by messing with preprocessor definitions.
However, any code written for linux which:
Uses a Linux driver
Directly accesses the kernel
Relies on any code which does either of these two things (and doesn't have a Windows counterpart)
will quite definitely not work, regardless of how much you modify the code.
Much as it tries to, Cygwin cannot fully emulate (yes it is an emulator, of sorts) everything a POSIX system can normally do. Cygwin is not windows, just a conversion layer from its own machine language.
For more information, read cygwin's wikia
Can I just write programs like I did for Linux without any major
changes when using Cygwin?
The platforms are not identical, so you can not realistically expect to write the program in Linux, and then POOF expect it to build and work under Cygwin. But if you don't use things not available under Windows, then you won't need major changes. And you can write non-trivial programs, which will build and work on both, perhaps needing a few #ifdefs in places.
From your question I take it you want to work on Linux, but write programs for running under Cygwin. In that case you must also build and test it in the Cygwin environment all the time, so:
Use version control, commit often. I recommend a DVCS like git or mercurial which have separate commit and push, it will allow you to do commits more freely.
Whenever you commit/push, do checkout/pull and build on the Cygwin host. You can do this manually or automatically (by simple custom script polling the version control, or by Jenkins or something).
When ever your code stops building or working under Cygwin, fix it before continuing with new code.
If Cygwin is not absolute requirement, then I would look into using Qt SDK. It can be used for non-Qt projects too, the MinGW toolchain on Windows is very similar to gcc on Linux. And if you're willing to use Qt, then it has all sorts of platform-independent features for things you might want to do, such as discover locations of standard directories for saving files, use threads, print things, have GUI...
I am required to write a C++ application to run on an embedded Linux setup (DMP Vortex86DX processor). The vendor provides a minimal linux installation image that can be installed to the board and contains appropriate hardware drivers. My question is motivated by the answer to my previous question about writing Linux software on a particular kernel to run on a different kernel . I don't really know where to start when it comes to writing the software with regards to ensuring compatibility.
My instinctive approach would be to install the same versions of g++ on the embedded device and on my desktop development machine, write the application on the dev maching, copy to the board and compile it there. This seems madness though and I find it hard to believe that this is how embedded software is developed. With regards to the answer to my previous question, is there a way I can simply build on my desktop but use the version of glibc that exists on the embedded device - if so how can enforce linkage to a specific version? Or is it possible to build everything statically so that the application doesn't link to anything dynamically (I doubt this is possible).
I am a total novice to embedded development, and foresee months of frustration unless I can get hold of some good advice or resources. Any pointers or suggestion of where to start will be very gratefully received no matter how simple or trivial they seem - I really am starting at the very bottom with regards to embedded stuff.
OK, given the fact that the Vortex86SX/DX/MX claims to be x86 compatible, a small set of compiler switches should enable you to compile code for your target machine: -m32 to ensure 32bit code, and no -march switch targeting a specific CPU.
Then you'll need to link your code. As long as you don't use anything fancy, but simple established glibc functions, I'd expect the ABI to be the same on your development machine and the embedded system. In other words, you compile against your host libraries, copy the binary to the embedded system, and it should simply run using the libraries available there.
If X-Linux were to use some other libc, like uclibc or similar, then you'd need a cross compiler on your host. I have little experience with Ubuntu in that regard, but I know that the sys-devel/crossdev package for Gentoo linux makes generation of cross-compilers very easy. This can be both for different architectures (not needed in your case) and different libraries (like e.g. uclibc).
I'd say simply give copying the binaries a try, and report back if you encounter any problems there.
I'm very new to this C++ and Qt Creator thing, I'm using Qt Creator in Mac OS X.
Is there an easy way to compile for Windows and Linux platform also?
The current way I'm doing is copying the source file to a Windows machine (with Qt) and compile it, which takes a lot of time.
Is there a command or something that can get all 3 executables at once?
It's not supported out of the box and you might end up messing between the different flavours
I strongly suggest, for such a goal:
- to use either centralised (svn) or distributed (git, hg) SCM
- to use continuus integration with 3 agents, each one in a different platform (can be VM or physical computer). You can use hudson or cruise control
This way:
- you develop locally, on whatever platform you prefer
- you push / commit / submit your changes
- the buildbox compiles on all platforms (while you can still work on the next feature)
- ideally, you run your unit tests as well
- once all builds on all platforms are finished, you got a status and a build on all targets
This is fairly useful when wanting to deal with more than one version of Qt or compiler : the return value is definitely worth the time invested in the setup (and it scales well)
It is far from trivial, and Trolltech didn't like the idea (by making it harder than it should be).
There is Cross compiling Qt/Win Apps on Linux on the Internet which will help (only directories might be different for Mac, commands should be the same).
After you have cross-compiled, you'll need to create a shortcut to Qt Creator with a custom PATH that has your cross-compiler directory prepended to the rest of the PATH. That way you can ensure it is used. This is not recommended though.
Why not just use a properly set up VM?
is there any development environments that allow you to have one code base that can compile to Linux, Mac OS, and Windows versions without much tweaking? I know this is like asking for where the Holy Grail is burred, but maybe such a thing exists. Thanks.
This is achieved through a number of mechanisms, the most prominent being build systems and specific versions of code for certain systems. What you do is write your code such that, if it requires an operating system API, it calls a specific function. By example, I might use MyThreadFunction(). Now, when I build under Linux I get a linux specific version of this MyThreadFunction() that calls pthread_create() whereas the windows version calls CreateThread(). The appropriate includes are also included in these specific platform-files.
The other thing to do is to use libraries that provide consistent interfaces across platforms. wxWidgets is one such platform for writing desktop apps, as is Qt and GTK+ for that matter. Any libraries you use it is worth trying to find a cross-platform implementation. Someone will undoubtedly mention Boost at some point here. The other system I know if is the Apache Portable Runtime (APR) that provides a whole array of things to allow httpd to run on Windows/Linux/Mac.
This way, your core code-base is platform-agnostic - your build system includes the system specific bits and your code base links them together.
Now, can you do this from one desktop? I know you can compile for Windows from Linux and so probably for Mac OS X from Linux, but I doubt if you can do it from Windows-Linux. In any case, you need to test what you've built on each platform so my advice would be to run virtual machines (see vmware/virtualbox).
Finally, editors/environments: use whatever suits you. I use either Eclipse/GVim on Linux and Visual Studio on Windows - VS is my "Windows build system".
Maybe something like CodeBlocks?
Qt is a good library/API/framework for doing this in C++, and Qt Creator is a very pleasant IDE for it.
I've heard this is possible. Your compiler would need to support this. The only one that I know that does is GCC but it obviously requires a special configuration. I, however, have never used this feature. I've only seen that it exists.
What you are looking for is called "Cross Compiling"
My company is thinking of dumping InstallShield and move to something else, mainly because of the poor experience it had with it, mostly on Linux.
Our product is a C++ application (binaries, shared libraries) targeted at Windows and Linux (Red Hat).
The installer itself isn't required to do anything special, just dump some binaries and shared libraries and sometime execute an external process. Things like version upgrading through the installer isn't necessary, this is handled after the installer finishes.
I thought of suggesting using NSIS on Windows and RPM on Linux.
What are the recommended installer systems to use when deploying to Windows/Linux? Something that is cross platform to prevent maintaining two installers is a definite plus.
For Windows I would definitively use NSIS. It's very lightweight, easy to code and very simple to understand. Using msis would just be a killer - it generates guid for every file so you can get upgrades for free and stuff but truth being said, you never end up using any of these.
Regarding Linux I would go for RPM and Deb. They're probably the two biggest packaging system so you'll be targeting most of the Linux users. I've never tried RPM but creating a Deb package is fairly straightforward.
See also:
What to use for creating a quick and light setup file?
Packaging to use to deploy cross-platform?
And even:
Creating installers for complex cross-platform programs
There's a tool called BitRock Installer which can create installers for Windows, Linux and OS X.
However, I think that if you target RedHat it would be better to provide native packages for that platform (that is .rpm).
For C++ projects, I'd go with cmake/cpack, if you are also willing to change your build system. Great support, strongly cross-platform. cpack has various generators, NSIS is one..
Take a look at InstallJammer. It will handle both platforms from the same build project, and you can have the installer register the package with the RPM database as well if that's your requirement.
You may want to consider our tool BitRock InstallBuilder , it can generate installers for Windows and Linux from a single project file and also RPMs. Is your application based on Qt? Our clients include the makers of Qt, Nokia (previously Trolltech) and they use it to package their Qt Creator product. We encourage to give InstallBuilder a try and contact our support with any questions or suggestions you may have.