The GEARS Apptainer/Singularity image can be pulled from sylabs:

singularity pull gears.sif library://jintonic/geant4/gears

or

apptainer pull library://jintonic/geant4/gears

Note that you may need to set the location of your Apptainer remote library before pull:

apptainer remote add sylabs https://cloud.sylabs.io
apptainer remote use sylabs
apptainer remote list

The sif file can be directly used as an executable:

./gears.sif example.mac

For developer

gears.def in this folder is used to generate the Apptainer/Singularity images from the GEARS Docker image using the following commands:

cd gears/INSTALL/Apptainer
sudo singularity build gears.sif gears.def

You must run the build command with sudo. If you don’t have the privilege to run sudo, you can use the remote build option provided by Singularity to build the image in https://cloud.sylabs.io:

singularity build -r gears.sif gears.def

I sign and push the image to https://cloud.sylabs.io/library/jintonic/geant4/gears using the following commands:

singularity sign gears.sif
singularity push gears.sif library://jintonic/geant4/gears:latest