/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/ is in singularity-container 2.4.2-4.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/checks.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/deffile-driver-arch.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/deffile-driver-busybox.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/deffile-driver-debootstrap.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/deffile-driver-docker.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/deffile-driver-localimage.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/deffile-driver-self.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/deffile-driver-shub.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/deffile-driver-yum.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/deffile-driver-zypper.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/deffile-post.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/deffile-sections.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/environment.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/environment.tar
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/functions
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/main-deffile.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/main-dockerhub.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/main-null.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/post.sh
/usr/lib/x86_64-linux-gnu/singularity/bootstrap-scripts/pre.sh