--On Wednesday, November 20, 2019 4:51 PM -0500 Jonathan Billings billings@negate.org wrote:
On Nov 20, 2019, at 16:17, Kenneth Porter shiva@sewingwitch.com wrote: (How does systemd know the difference between generated files and hand-crafted ones? Can one just remove the fstab entry once the generated one is present? That would make migration easier.)
Mount units created by the systemd generator are dynamically created each boot. You can create a persistent one in /etc/systemd/system to override the dynamic one from fstab.
Where does it put the dynamic ones? I've never gone down that rabbit hole...
Ok, I braved the rabbit hole and found it puts them in a subdirectory of /run/systemd, a volatile filesystem recreated at boot time. So one could copy the generated file to /etc/systemd/system which has higher priority than the generated files and thereby make them permanent. One then removes the fstab entry.
https://www.freedesktop.org/software/systemd/man/systemd.generator.html
My sense is that static, simple mounts for which drivers are present at boot time are best placed in fstab, and more complex dynamic mounts like network mounts are best placed in units.