On Tue, Jan 16, 2024 at 02:17:05PM +0100, hw wrote: > On Tue, 2024-01-16 at 08:03 -0500, Greg Wooledge wrote: > > On Tue, Jan 16, 2024 at 01:43:23PM +0100, hw wrote: > > > There's only a bunch of links in that directory, apparently all > > > pointing to files that don't exist. Don't you have that? > > > > unicorn:~$ ls -l /run/user/1000/systemd/units > > total 0 > > lrwxrwxrwx 1 greg greg 32 Jan 4 10:33 invocation:at-spi-dbus-bus.service > > -> bfec6466520a4586b8c9205c235ccc92 > > [...] > > I guess that's normal, then. It seems they're using the symlink target > > as the actual *data*, not a link to another file that contains the data. > > Why? I have no idea. I seem to recall one of the BSDs doing something > > like this, but I never fully understood the rationale. Something about > > atomic operations, maybe? > > > > I consider it as alarming rather than normal when I can't access data > on my own computer.
You can access it just fine. You just don't *understand* it. (Neither do I.) > And I do want to know what this unit file for firefox contains and > does and how it is being brought about. If it's a symlink whose name begins with "invocation:" and whose target is a 32-hex-digit (128-bit) value, like the one shown above, then you are seeing everything there is to see. I don't know what the 128-bit number is used for, but that number *is* the data. Of that, I'm certain. I did a bit of Google searching, and I think this is something called an "InvocationID". > > lrwxrwxrwx 1 greg greg 32 Jan 4 10:33 invocation:at-spi-dbus-bus.service > > -> bfec6466520a4586b8c9205c235ccc92 unicorn:~$ systemctl --user show -p InvocationID at-spi-dbus-bus.service InvocationID=bfec6466520a4586b8c9205c235ccc92 <https://sleeplessbeastie.eu/2022/07/01/how-to-display-systemd-journal-for-specific-service-since-it-started/> describes this as "a unique 128-bit ID identifying each runtime cycle of the unit". There is also a man page systemd-id128(1) ("man systemd-id128") but it doesn't describe things in a way I can currently understand. It seems to reference another page sd-id128(3) which I do not have, but which I can find online at <https://manpages.debian.org/bookworm/libsystemd-dev/sd-id128.3.en.html> ... which, OK, that's pretty boring. What I cannot find anywhere is a basic explanation of *what this ID is used for*. Maybe it's just a fancy PID? I dunno, it's all very shrouded in mystery.
