From 6730c32c983fdf59fbc802d098b69abd76f3d92e Mon Sep 17 00:00:00 2001
From: Robert Helgesson <robert@rycee.net>
Date: Sun, 18 Feb 2018 16:39:28 +0100
Subject: [PATCH] systemd: replace use of `who` command

Curiously the `who` command sometimes does not list logged-in users,
resulting in systemd not being reloaded. Instead we use

    systemctl --user is-system-running

to more directly detect whether systemd is running.

(cherry picked from commit e307ceeee7fea63dbe898cc995917b48345a3d85)
---
 modules/systemd.nix | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/modules/systemd.nix b/modules/systemd.nix
index 9eaba7c22..ce3c2c1bb 100644
--- a/modules/systemd.nix
+++ b/modules/systemd.nix
@@ -159,14 +159,16 @@ in
           legacyReloadCmd = ''
             bash ${./systemd-activate.sh} "''${oldGenPath=}" "$newGenPath"
           '';
+
+          ensureRuntimeDir = "XDG_RUNTIME_DIR=\${XDG_RUNTIME_DIR:-/run/user/$(id -u)}";
         in
           ''
-            if who | grep -q '^${config.home.username} '; then
-              XDG_RUNTIME_DIR=''${XDG_RUNTIME_DIR:-/run/user/$(id -u)} \
+            if ${ensureRuntimeDir} ${cfg.systemctlPath} --quiet --user is-system-running 2> /dev/null; then
+              ${ensureRuntimeDir} \
               PATH=${dirOf cfg.systemctlPath}:$PATH \
                 ${if cfg.startServices then autoReloadCmd else legacyReloadCmd}
             else
-              echo "User ${config.home.username} not logged in. Skipping."
+              echo "User systemd daemon not running. Skipping reload."
             fi
           ''
       );