archlinux systemd --user

my arch system has installed nearly four years.

because systemd make a lot of change and i find my mpd and ssh-agent can not work as use service

when i run
```
systemctl --user
```
return bus file not exist

i find it lot and finally

if find a lot diff of /etc/pam.d/systemd-user and  /etc/pam.d/systemd-user.pacnew
```
# This file is part of systemd.
# systemd-user.pacnew (new file)
# Used by systemd --user instances.

account  include system-login

session  include system-login
```

```
# This file is part of systemd.
# systemd-user(old file)
# Used by systemd --user instances.

account  include systemd-login

session  include systemd-login
```

i cp systemd-user.pacnew to systemd-user

and reboot the system and it works.

that's all