Incorrect user in ACPI script in Void Linux

In previous article Closing laptop lid does not lock screen on Void Linux I showed how to lock the screen when closing a laptop lid on Void Linux. It required to know a user under which the mate-session was started. Default ACPI script in Void Linux does not detect correct user.

The code below attempts to detect a user:

PID=$(pgrep dbus-launch)
export USER=$(ps -o user --no-headers $PID)

But it fails, because there are two dbus-launch processes on my Void Linux:

# ps auxf | grep dbus-launch
root       981  Dec16   0:00 dbus-launch --autolaunch 47a2e --binary-syntax --close-stderr
marat     1038  Dec16   0:00 dbus-launch --sh-syntax --exit-with-session

With such snapshot of current processes, /etc/acpi/handler.sh would find that PID=981 and USER=root. Later running sudo -u $USER mate-screensaver-command -l would not lock the screen, because USER is not `marat.

Quick workaround is to update /etc/acpi/handler.sh and iterate over all dbus-lanuch processes:

USER=
PIDS=$(pgrep dbus-launch)
for p in $PIDS; do
    USER=$(ps -o user --no-headers $p)
    if [ "$USER" != "root" ]; then
        # stop at first non-root user
        break
    fi
done

export USER