I got audio working in Arch Linux without problems yesterday, but at some point it stopped working again:$ alsamixer cannot open mixer: No such file or directory$ vlc foo.mp4...[0x7f1388006be8] alsa audio output error: cannot open ALSA device default: No such file or directoryalsamixer runs fine as root, so it seems to be a permission problem. All the audio devices are owned by root:audio:$ ls -l /dev/sndtotal 0drwxr-xr-x 2 root root       80 Aug  6 22:54 by-pathcrw-rw---- 1 root audio 116,  7 Aug  6 22:54 controlC0crw-rw---- 1 root audio 116, 10 Aug  6 22:54 controlC1crw-rw---- 1 root audio 116,  6 Aug  6 22:54 hwC0D0crw-rw---- 1 root audio 116,  9 Aug  6 22:54 hwC1D0crw-rw---- 1 root audio 116,  5 Aug  6 22:54 pcmC0D0ccrw-rw---- 1 root audio 116,  4 Aug  6 22:54 pcmC0D0pcrw-rw---- 1 root audio 116,  3 Aug  6 22:54 pcmC0D1pcrw-rw---- 1 root audio 116,  2 Aug  6 22:54 pcmC0D2ccrw-rw---- 1 root audio 116,  8 Aug  6 22:54 pcmC1D3pcrw-rw---- 1 root audio 116,  1 Aug  6 22:54 seqcrw-rw---- 1 root audio 116, 33 Aug  6 22:54 timer$ getfacl /dev/snd/*getfacl: Removing leading '/' from absolute path names# file: dev/snd/by-path# owner: root# group: rootuser::rwxgroup::r-xother::r-x# file: dev/snd/controlC0# owner: root# group: audiouser::rw-group::rw-other::---# file: dev/snd/controlC1# owner: root# group: audiouser::rw-group::rw-other::---# file: dev/snd/hwC0D0# owner: root# group: audiouser::rw-group::rw-other::---# file: dev/snd/hwC1D0# owner: root# group: audiouser::rw-group::rw-other::---# file: dev/snd/pcmC0D0c# owner: root# group: audiouser::rw-group::rw-other::---# file: dev/snd/pcmC0D0p# owner: root# group: audiouser::rw-group::rw-other::---# file: dev/snd/pcmC0D1p# owner: root# group: audiouser::rw-group::rw-other::---# file: dev/snd/pcmC0D2c# owner: root# group: audiouser::rw-group::rw-other::---# file: dev/snd/pcmC1D3p# owner: root# group: audiouser::rw-group::rw-other::---# file: dev/snd/seq# owner: root# group: audiouser::rw-group::rw-other::---# file: dev/snd/timer# owner: root# group: audiouser::rw-group::rw-other::---I'm not in the audio group, as recommended by the ALSA instructions:$ groupswheel usersA discussion pointed me to an explanation of why adding the group is unnecessary and sometimes harmful. From there the user groups info said None of these groups is needed for standard desktop permissions like sound, 3D, printing, mounting, etc. as long as the logind session isn't broken. Following directions to session permission troubleshooting, I finally found a discrepancy - it says the output of loginctl show-session $XDG_SESSION_ID should contain Remote=no and Active=yes, but I get the following:$ loginctl show-session $XDG_SESSION_IDControlGroupHierarchy=/userResetControllers=cpuNAutoVTs=6KillExcludeUsers=rootKillUserProcesses=noIdleHint=yesIdleSinceHint=0IdleSinceHintMonotonic=0InhibitDelayMaxUSec=5sHandlePowerKey=poweroffHandleSuspendKey=suspendHandleHibernateKey=hibernateHandleLidSwitch=suspendIdleAction=ignoreIdleActionUSec=30minPreparingForShutdown=noPreparingForSleep=noFrom there I found info on preserving the session, which doesn't seem to be applicable - my /etc/X11/xinit/xserverrc is unmodified since the installation:$ ls -l /etc/X11/xinit/xserverrc-rw-r--r-- 1 root root 132 Oct 31  2012 /etc/X11/xinit/xserverrcSLiM seems to be running fine:$ systemctl status slim.serviceslim.service - SLiM Simple Login Manager   Loaded: loaded (/usr/lib/systemd/system/slim.service; enabled)   Active: active (running) since Sat 2013-08-10 00:00:39 CEST Main PID: 258 (slim)   CGroup: name=systemd:/system/slim.service            258 /usr/bin/slim -nodaemon            292 /usr/bin/X -nolisten tcp vt07 -auth /var/run/slim.auth            416 /usr/bin/gnome-keyring-daemon --daemonize --login            418 awesome            423 /usr/bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session            472 xscreensaver -no-splash            479 firefox            481 java -Xmx192M -jar /usr/share/java/jedit/jedit.jar -reuseview            483 pidgin            485 xterm            500 bash            581 /usr/lib/at-spi2-core/at-spi-bus-launcher            641 xterm            643 bash           1006 git gui           1007 wish /usr/lib/git-core/git-gui --           1367 dbus-launch --autolaunch e943bbb765d74fceb0393a55ceebfd1d --binary-syntax --close-stderr           1368 /usr/bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session           1403 ekiga           1405 /usr/lib/GConf/gconfd-2           1476 thunar           1478 /usr/lib/xfce4/xfconf/xfconfd           1589 systemctl status slim.serviceWhat do I need to do to fix the logind session, and thus (presumably) the audio permissions?
How to preserve the logind session in Arch Linux?
arch linux;audio;systemd;alsa;logind