apprun

AppRun is a small launcher used in the AppImage packaging system to start applications that are packaged as AppImages. It serves as the primary entry point for an AppDir, the self-contained folder used to build an AppImage, and is typically placed at the root of the bundle.

The main role of AppRun is to bootstrap the contained application. When an AppImage is executed, AppRun locates the application’s main executable inside the bundle, prepares a suitable runtime environment (for example adjusting library paths and data directories), and then launches the application with the command-line arguments passed to the AppImage. It is designed to be lightweight, portable across Linux distributions and hardware architectures, and capable of handling both graphical and console applications.

Implementation details can vary between AppImages, but the common pattern is that AppRun is provided as a small binary (or, in some cases, a simple script) that knows how to locate the bundled executable within the AppDir and to invoke it. The exact startup logic may depend on the toolkit or build process used for the AppImage, but the consistent behavior is to provide a reliable, architecture-specific launcher at the root of the AppDir.

Relation to the broader ecosystem: AppRun is an integral part of the AppImage concept, enabling a uniform startup experience across different Linux distributions without requiring system-wide installation. It contributes to the portability and ease of distribution that AppImages aim to provide, while keeping the startup process encapsulated within the AppDir.