man: extend description of --boot

diff --git a/man/systemd-tmpfiles.xml b/man/systemd-tmpfiles.xml
index a6246844cbe05e1961439d225822b3b196b40a00..735f59cc11acc8b5a6d679b7edcfb36fd0269bdf 100644 (file)
--- a/man/systemd-tmpfiles.xml
+++ b/man/systemd-tmpfiles.xml
@@ -144,8 +144,10 @@
 
       <varlistentry>
         <term><option>--boot</option></term>
-        <listitem><para>Also execute lines with an exclamation mark.
-        </para></listitem>
+        <listitem><para>Also execute lines with an exclamation mark. Lines that are not safe to be executed
+        on a running system may be marked in this way. <command>systemd-tmpfiles</command> is executed in
+        early boot with <option>--boot</option> specified and will execute those lines. When invoked again
+        later, it should be called without <option>--boot</option>.</para></listitem>
       </varlistentry>
 
       <varlistentry>