Systemd geniuses wanted - login and logout functions with systemd and root access

[oshunluvr]

As an experiment I am attempting to have some bind mounts created when a user logs in and then unmounted on log out. I have a working set of scripts but I would like to learn how to use systemd to control the actions.

My goal is to have all users have a set of private folders bind-mounted to their home at log in (not at boot-up) and disconnected when they log out. I used to be able to do this with X but since we're moving away from X soon to Wayland and systemd is new and powerful, I'd like to figure this one out. I've read dozens of pages and forums but nothing is complete or on-target.

Here's the systemd.service I tried:

[FONT=monospace][COLOR=#5454FF][B]/etc/systemd/system[/B][/COLOR][COLOR=#000000]$ cat bindmounts.service  [/COLOR]
[Unit]
Description = Mount bindmounts  
After=network.target

[Service]
User=root
Type=oneshot
RemainAfterExit=true
StandardOutput=journal
ExecStart = /etc/systemd/user/bindin.sh
Execstop = /etc/systemd/user/bindout.sh

[Install]
WantedBy=default.target

[/FONT]

I really have no clue what I'm doing.

[GreyGeek]

Apparently it doesn't work?

[oshunluvr]

Nope. I'm not even close. My scripts have mount in them so must be run as root, but no environmental variables are passed to the script (I need $USER or $LOGNAME in the script). None of the tips on how to pass variables work. I either get a blank or "root" passed, but no username.

I tried

Environment="ONE=${USER}" as suggested by the man pages, but what gets passed is $USER not the value of $USER.

I tried running the service as a user then setting "User=root" and that gets me to the same place. Either the mount fails because of lack of permission or the mount fails because it tries to mount to /home//Documents instead of /home/$USER/Documents.

[GreyGeek]

From "man systemd.unit" is the following:

       |"%u"      │ User name                   │ This is the name of the     │
       │          │                             │ user running the service    │
       │          │                             │ manager instance. In case   │
       │          │                             │ of the system manager this  │
       │          │                             │ resolves to "root".         │
       ├──────────┼─────────────────────────────┼─────────────────────────────┤
       │"%U"      │ User UID                    │ This is the numeric UID of  │
       │          │                             │ the user running the        │
       │          │                             │ service manager instance.   │
       │          │                             │ In case of the system       │
       │          │                             │ manager this resolves to    │
       │          │                             │ "0".                        │
       ├──────────┼─────────────────────────────┼─────────────────────────────┤
       │"%h"      │ User home directory         │ This is the home directory  │
       │          │                             │ of the user running the     │
       │          │                             │ service manager instance.   │
       │          │                             │ In case of the system       │
       │          │                             │ manager this resolves to    │
       │          │                             │ "/root".

What's needed is an "after=login.target", but I couldn't find one. Maybe write one?

[oshunluvr]

I'm going to call this "ABANDONDED" as I don't think systemd is suited for this.

Turns out there is functionality called "pam_mount" which is designed for just this purpose.