man: Document when pam_systemd sets XDG_RUNTIME_DIR (#5570)

https://github.com/systemd/systemd/blob/f97b34a6/src/login/pam_systemd.c#L439

diff --git a/man/pam_systemd.xml b/man/pam_systemd.xml
index 6e1aa0dd9a64a79f6c6c74d1afb0cfde166b7dce..cef5445c1ce4609b116df98ac8e958606228b89e 100644 (file)
--- a/man/pam_systemd.xml
+++ b/man/pam_systemd.xml
@@ -88,7 +88,7 @@
       and so will the user's slice unit.</para></listitem>
 
       <listitem><para>If the last concurrent session of a user ends,
-      the <varname>$XDG_RUNTIME_DIR</varname> directory and all its
+      the user runtime directory <filename>/run/user/$UID</filename> and all its
       contents are removed, too.</para></listitem>
     </orderedlist>
 
@@ -192,7 +192,8 @@
         offers the greatest possible file system feature set the
         operating system provides. For further details, see the <ulink
         url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
-        Base Directory Specification</ulink>.</para></listitem>
+        Base Directory Specification</ulink>. <varname>$XDG_RUNTIME_DIR</varname>
+        is not set if the current user is not the original user of the session.</para></listitem>
       </varlistentry>
 
     </variablelist>