On Mon 24 Jan 2022, at 12:45, Greg Wooledge <g...@wooledge.org> wrote: > On Mon, Jan 24, 2022 at 09:51:05AM +0000, Gareth Evans wrote: >> I've just noticed that: >> >> $ who >> >> and >> >> $ users >> >> both return nothing, with or without sudo. > >> Can anyone replicate this or suggest what may have happened? I'm fairly >> sure I've used who since upgrading from Buster. > > Definitely can't replicate. "who" gives me 28 lines of output for all > of my terminals. > > As far as suggesting a cause -- we'd need more info.
> Which init system > are you using? systemd. But for root on ZFS per https://openzfs.github.io/openzfs-docs/Getting%20Started/Debian/Debian%20Buster%20Root%20on%20ZFS.html (adjusted for Bullseye) it's standard Debian-mate amd64 > How are you logging in? Logging into Mate with lightdm > Are you using any terminal > emulators, and if so, which one(s)? mate-terminal > > Is the /var file system full? (Or any mount underneath /var if you have > such.) $ sudo zfs list NAME USED AVAIL REFER MOUNTPOINT bpool 172M 660M 96K /boot bpool/BOOT 170M 660M 96K none bpool/BOOT/debian 170M 660M 170M /boot rpool 67.6G 45.7G 192K / rpool/ROOT 11.2G 45.7G 192K none rpool/ROOT/debian 11.2G 45.7G 11.2G / rpool/data 200K 45.7G 200K /data rpool/home 15.0G 45.7G 9.27G /home rpool/large 3.06G 45.7G 3.06G /large rpool/backup1 4.94G 45.7G 1.03G /backup1 rpool/backup2 15.7G 45.7G 3.94G /backup2 rpool/swap 8.50G 54.2G 108K - rpool/var 9.06G 45.7G 412K /var rpool/var/cache 192M 45.7G 192M /var/cache rpool/var/lib 6.29G 45.7G 720K /var/lib rpool/var/lib/docker 19.0M 45.7G 19.0M /var/lib/docker rpool/var/lib/libvirt 5.94G 45.7G 5.94G /var/lib/libvirt rpool/var/lib/mysql 335M 45.7G 246M /var/lib/mysql rpool/var/log 363M 45.7G 363M /var/log rpool/var/spool 103M 45.7G 103M /var/spool rpool/var/tmp 250M 45.7G 250M /var/tmp rpool/var/www 1.89G 45.7G 1.40G /var/www > Have you done anything unique or unusual to your system that would cause > it not to log sessions in /var/run/utmp? Not afaik > >> $ sudo strace who >> <snip> >> access("/var/run/utmpx", F_OK) = -1 ENOENT (No such file or >> directory) >> openat(AT_FDCWD, "/var/run/utmp", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such >> file or directory) >> access("/var/run/utmpx", F_OK) = -1 ENOENT (No such file or >> directory) >> openat(AT_FDCWD, "/var/run/utmp", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such >> file or directory) >> close(1) = 0 >> close(2) = 0 >> exit_group(0) = ? >> +++ exited with 0 +++ > > Your /var/run/utmp file is missing. That's definitely going to cause > a problem here. > > Here's what mine looks like: > > unicorn:~$ df /var/run > Filesystem 1K-blocks Used Available Use% Mounted on > tmpfs 1215580 1456 1214124 1% /run > unicorn:~$ ls -ld /var/run > lrwxrwxrwx 1 root root 4 Jan 11 2018 /var/run -> /run/ > unicorn:~$ ls -l /var/run/utmp > -rw-rw-r-- 1 root utmp 12288 Jan 20 15:08 /var/run/utmp > > I don't know what happened to yours, but since /run is an in-memory > file system, all of the stuff inside it (including the utmp file) has > to be created at boot time, or at login time at the very latest. > > You could try creating the file with the correct user/group/perms and > see if that helps, but that probably won't survive the next reboot. /var/run$ sudo touch utmp /var/run$ sudo chown root:utmp utmp /var/run$ sudo chmod 664 utmp /var/run$ ls -l utmp -rw-rw-r-- 1 root utmp 0 Jan 25 00:08 utmp /var/run$ who /var/run$ [logout, login] /var/run$ ls -l /var/run/utmp -rw-rw-r-- 1 root utmp 384 Jan 25 00:17 /var/run/utmp $ who user tty7 2022-01-25 00:17 (:0) $ sudo reboot ... $ ls -l /var/run/utmp ls: cannot access '/var/run/utmp': No such file or directory > > You could also try rebooting and see if it gets created correctly. If > it doesn't, then I guess you get to dive into the internals of your > init system to discover what's going wrong. > user@qwerty:~$ sudo service systemd-update-utmp status ● systemd-update-utmp.service - Update UTMP about System Boot/Shutdown Loaded: loaded (/lib/systemd/system/systemd-update-utmp.service; static) Active: active (exited) since Tue 2022-01-25 01:13:05 GMT; 1min 49s ago Docs: man:systemd-update-utmp.service(8) man:utmp(5) Process: 1375 ExecStart=/lib/systemd/systemd-update-utmp reboot (code=exited, status=0/SUCCESS) Main PID: 1375 (code=exited, status=0/SUCCESS) CPU: 9ms Jan 25 01:13:05 qwerty systemd[1]: Starting Update UTMP about System Boot/Shutdown... Jan 25 01:13:05 qwerty systemd[1]: Finished Update UTMP about System Boot/Shutdown. user@qwerty:~$ sudo grep -i utmp /var/log/daemon.log Jan 24 08:59:27 qwerty systemd[1]: Starting Update UTMP about System Boot/Shutdown... Jan 24 08:59:27 qwerty systemd[1]: Finished Update UTMP about System Boot/Shutdown. Jan 24 08:59:35 qwerty lightdm[2594]: Failed to write utmpx: No such file or directory Jan 24 08:59:36 qwerty systemd[1]: Starting Update UTMP about System Runlevel Changes... Jan 24 08:59:36 qwerty systemd[1]: systemd-update-utmp-runlevel.service: Succeeded. Jan 24 08:59:36 qwerty systemd[1]: Finished Update UTMP about System Runlevel Changes. Jan 24 09:32:17 qwerty systemd[1]: Starting Update UTMP about System Boot/Shutdown... Jan 24 09:32:17 qwerty systemd[1]: Finished Update UTMP about System Boot/Shutdown. Jan 24 09:32:27 qwerty lightdm[2561]: Failed to write utmpx: No such file or directory Jan 24 09:32:27 qwerty systemd[1]: Starting Update UTMP about System Runlevel Changes... Jan 24 09:32:27 qwerty systemd[1]: systemd-update-utmp-runlevel.service: Succeeded. Jan 24 09:32:27 qwerty systemd[1]: Finished Update UTMP about System Runlevel Changes. Jan 24 23:46:28 qwerty systemd[1]: Starting Update UTMP about System Boot/Shutdown... Jan 24 23:46:28 qwerty systemd[1]: Finished Update UTMP about System Boot/Shutdown. Jan 24 23:46:38 qwerty systemd[1]: Starting Update UTMP about System Runlevel Changes... Jan 24 23:46:38 qwerty systemd[1]: systemd-update-utmp-runlevel.service: Succeeded. Jan 24 23:46:38 qwerty systemd[1]: Finished Update UTMP about System Runlevel Changes. Jan 24 23:46:38 qwerty lightdm[2890]: Failed to write utmpx: No such file or directory Jan 25 00:15:24 qwerty systemd[1]: Starting Update UTMP about System Boot/Shutdown... Jan 25 00:15:24 qwerty systemd[1]: Finished Update UTMP about System Boot/Shutdown. Jan 25 00:15:32 qwerty lightdm[2642]: Failed to write utmpx: No such file or directory Jan 25 00:15:33 qwerty systemd[1]: Starting Update UTMP about System Runlevel Changes... Jan 25 00:15:33 qwerty systemd[1]: systemd-update-utmp-runlevel.service: Succeeded. Jan 25 00:15:33 qwerty systemd[1]: Finished Update UTMP about System Runlevel Changes. Jan 25 01:13:05 qwerty systemd[1]: Starting Update UTMP about System Boot/Shutdown... Jan 25 01:13:05 qwerty systemd[1]: Finished Update UTMP about System Boot/Shutdown. Jan 25 01:13:14 qwerty lightdm[2527]: Failed to write utmpx: No such file or directory Jan 25 01:13:15 qwerty systemd[1]: Starting Update UTMP about System Runlevel Changes... Jan 25 01:13:15 qwerty systemd[1]: systemd-update-utmp-runlevel.service: Succeeded. Jan 25 01:13:15 qwerty systemd[1]: Finished Update UTMP about System Runlevel Changes. Lightdm seems to be struggling with [I presume /var/run/]utmpx (which also doesn't exist) In a (new and un-updated VM of Deb 11.0 Mate): /# grep -ir utmp ... var/lib/plymouth/boot-duration:0.447:systemd-update-utmp.service ... but this doesn't appear on the host - is that significant? > Or... maybe you're just missing the /var/run symlink? Definitely check > that. /var$ ls -l lrwxrwxrwx 1 root root 4 Dec 8 2020 run -> /run Any further troubleshooting advice/instructions much appreciated - systemd.io and the Arch wiki don't seem to provide many pointers of where to begin for something like this. Thanks Gareth
