Deploy a Qt Application Binary on Linux, compatible with LSB

Question

I have developed a small application in Qt Creator on Ubuntu 12.04 which I want should run on any other linux distro (mostly different versions of CentOS and ubuntu), just like any portable application on windows does.

I want to be able to simply share the binary file of the Application, and run the application. I am able to successfully do this in windows, by just building the project in QT Creator and then putting the required libraries in the Application directory and then transfering them to other windows systems.

I searched all over and found out that I should be trying to build the project using LSB(Linux Standard Base) Compatibility, so that it runs on other linux distros. Is that the right way to do this?

I am very new to Qt and also to Linux (dont know much of Shell Scripting). Thus, I dont know how I should proceed to make the Application LSB Compliant.

I have refered to, the following links: Distributing Qt-based binaries on Linux and Deploying Qt applications on Linux but have not beem able to understand what I am suposed to do.

I also found this question here which states a very similar situation as mine, but because I am a novice, I dont know how I should do this.

Moreover, considering that the first two articles were written 6 years back, shouldn't there be a simpler way to deploy Qt apps on the linux platform now? I also saw something about static linking, is that the way to go? Isn't there a way by which all of this can be done through Qt Creator itself?

If there is no hope of creating a portable Qt Application for Linux, then is there a way, say a shell script or something that would combine all the steps required to compile the Qt project on another computer and run it. Say, download Qt-SDK if not present, run qmake and make and then the newly compiled application, if not already there, so that the user can run the program just by running one script.

Answer 1

Your problem here is not the Linux Standard Base, but rather the presence or not of the specific version of Qt you need (or a later one).

Exactly like on a Windows machine, a user may have any of Qt installed, or they may not have it at all. On Windows it is easier to check for the presence of a certain version of Qt than it is on Linux, thus it is easier to write install tools that automate the experience.

To solve your problem there are a few ways:

1. Inform the user that your program requires a certain version of Qt or higher, and let the user handle the problem
2. Learn how to create packages for every distribution you want to target and create specific packages
3. Use a program like 0Install or Elf Statifier to create a package/executable containing all the necessary libraries.

The latter is similar to what many Windows and Mac programs do (they include every library they need within the installer), but it is not the preferred way on Linux, which relies heavily on shared libraries.

Answer 2

Making a binary application compatible with any other Linux distro is practically impossible since you will never know in advance which libraries are available in distro X, or what version of that library is available. Even among a single distro (e.g. Ubuntu), binary application are almost never backward-compatible, since anything built on Ubuntu 12.04 will have dependencies on versions libraries which are installed on that version of Ubuntu, and trying to run that binary on Ubuntu 10.04 will most probably fail simply because it doesn't have a recent enough version of glibc or some other necessary library.

However, the idea can be much more implementable if you limit yourself to a finite list of distros and versions of those distros. You can then know which libraries are available for those distros, and aim for the lowest common denominator. I used to maintain a binary application which had to support several distros (Ubuntu, Fedora, OpenSUSE, SLED, Mandriva), and the way I would do it is install the oldest distro I was targeting on my build machine. That way, the binary application would be linked to the oldest versions of the libraries available on those distros. Unless there's a new major version of such a library (which happens quite rarely, and even then, distros usually distribute the previous major version for a while for compatibility purposes), your compiled binary will then be compatible with all your targeted distros.

Therefore, the quick piece of advice I would give for your situation, use the oldest LTS version of Ubuntu which is still supported (10.04 at the moment) for your development, and you should be pretty safe for most recent popular distros. For the application you already developped on Ubuntu 12.04, you should have no problem simply recompiling the same source on 10.04. Understand that you will never however achieve 100% compatibility with a compiled C++ Qt application.

If Qt is not all that important to you, you could use a higher-level or interpreted language such as Python, Java, Perl or Ruby. With such languages, you can usually count on the language implementation already being installed on the target distro.