How to Use the Command 'qtchooser' (with examples)

Qt is a popular framework for developing cross-platform applications. It provides a rich set of libraries to help developers create seamless desktop applications with captivating graphical interfaces. The command qtchooser is a utility that acts as a wrapper, allowing developers to easily switch between different versions of Qt development binaries. This flexibility is especially valuable for projects that may need to maintain compatibility with multiple versions of Qt. Using qtchooser, you can effortlessly manage your Qt environment, ensuring that you’re using the correct version for your specific development needs.

Use case 1: List available Qt versions from the configuration files

Code:

qtchooser --list-versions

Motivation: In a development environment where multiple Qt versions are installed, it becomes crucial to know which versions are available. This aids developers in choosing the appropriate version for their application development or testing needs. By listing available versions, developers can ensure that their project uses the correct Qt version, satisfying any specific version dependencies that it may have.

Explanation:

• --list-versions: This argument tells qtchooser to print out a list of all the Qt versions that are currently configured. It’s essentially querying the configuration files to display the available versions.

Example Output:

4
5
default

Here, the output shows that two versions of Qt (4 and 5) and a ‘default’ option are configured and available for use.

Use case 2: Print environment information

Code:

qtchooser --print-env

Motivation: Understanding the current Qt environment setup is key for debugging and ensuring consistency across different development setups. Printing the environment information helps developers identify which Qt version is set as the default, where the Qt binaries are located, and what options are currently active. This is especially helpful when moving projects between different development environments or when setting up a new environment.

Explanation:

• --print-env: This argument instructs qtchooser to print out environment variables and other relevant details about the current Qt setup. It provides insights into the paths and settings that are being used by the active Qt version.

Example Output:

QT_SELECT="default"
QTTOOLDIR="/usr/lib/qt5/bin"
QTLIBDIR="/usr/lib/qt5/lib"

The output indicates that the default Qt version is currently selected, and it specifies the directories for the Qt tools and libraries.

Use case 3: Run the specified tool using the specified Qt version

Code:

qtchooser --run-tool=tool --qt=version_name

Motivation: Different projects or components within a single project may require different versions of Qt. This use case allows a developer to specify both the tool they want to run (such as qmake or designer) and the version of Qt they want to use. This is particularly useful for ensuring compatibility with specific versions of Qt without having to change the global Qt version settings.

Explanation:

• --run-tool=tool: This specifies the Qt tool that the user wants to run, such as qmake which is commonly used to manage the build process for Qt projects.
• --qt=version_name: This specifies which version of Qt is to be used. The version_name corresponds to an entry in the configuration files, allowing for precise version selection.

Example Output: Assuming you’re running qmake with Qt version 5:

Running /usr/lib/qt5/bin/qmake

Here, the command indicates that it ran the qmake tool using the binaries located in the directory associated with Qt version 5.

Use case 4: Add a Qt version entry to be able to choose from

Code:

qtchooser --install version_name path/to/qmake

Motivation: As new versions of Qt get released, developers often need to install them and make them available for use with qtchooser. This use case demonstrates how to add a new version of Qt to the existing configuration, allowing it to be selected in development workflows. It’s essential for keeping up with the latest features and improvements offered in newer Qt releases.

Explanation:

• --install version_name: This specifies that a new Qt version is being added, with version_name acting as its identifier.
• path/to/qmake: This path points to the qmake executable associated with the new Qt version being installed, which is used as a reference point for the qtchooser configuration.

Example Output: No output is typically generated for this command, but it successfully adds the specified version. Checking with qtchooser --list-versions will show the new version available for selection.

Use case 5: Display help

Code:

qtchooser --help

Motivation: Getting help and understanding the options available with any command is vital, especially for new users or when exploring unfamiliar features. Displaying the help documentation offers a quick overview of what qtchooser can do, revealing all the available commands and options that can be utilized for more advanced usage scenarios.

Explanation:

• --help: By passing this argument, qtchooser enters a help mode where it displays a succinct summary of its options and usage patterns, acting as an immediate reference guide.

Example Output:

Usage: qtchooser [options]
Options:
  --list-versions          List all available versions
  --print-env              Show environment information
  --run-tool=tool          Run tool with specific Qt version
  --install name path      Add a new version
  --help                   Display this help

The output provides a helpful guide on qtchooser usage, explaining the available options and how they can be leveraged.

Conclusion

The qtchooser command is an invaluable utility for developers working within the Qt framework, offering a seamless way to manage multiple Qt versions and ensuring that development teams can adapt to diverse project requirements. Its various use cases—from listing available versions to setting up and switching between them—highlight its role in simplifying the development process and enhancing efficiency in Qt-based workflows. By understanding and applying these typical use cases, developers can easily manage their Qt environment and focus more on crafting high-quality applications.