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[lassoan (Andras Lasso)]

Since 2021 Slicer install tree has been fully portable: it can store all settings and extensions in the installation folder and the application can be launched from anywhere, without installation, by any user. This has the side effect that the installation folder has to be writable. See some more information here:

Slicer is now fully portable

Slicer can now be run from a portable drive (external drive, USB stick), along with all extensions, Python packages, settings, DICOM database, etc. - without installation. This can be used for easy distribution of Slicer to users, for example to be used as a free DICOM viewer for a folder full of DICOM files, or handing out preconfigured Slicer instance for a training course (see this related request). Since cache directory can be made local, too, the cache can be prepopulated with sample data s…

Slicer can be built with Slicer_STORE_SETTINGS_IN_APPLICATION_HOME_DIR=OFF to store settings and extensions in the user profile by default, but extensions that need to install additional Python packages must be installed by a user that has write access to the installation folder.