man: document that services need at least one of ExecStart= or ExecStop=

Fixes: #4521

diff --git a/man/systemd.service.xml b/man/systemd.service.xml
index 684029bdb445b49533a56b2e3ac91230cce88ef9..b707961a59fa0ae1c5424526f7d636635d4e4ce2 100644 (file)
--- a/man/systemd.service.xml
+++ b/man/systemd.service.xml
@@ -284,7 +284,9 @@
         providing multiple command lines in the same directive, or alternatively, this directive may be specified more
         than once with the same effect. If the empty string is assigned to this option, the list of commands to start
         is reset, prior assignments of this option will have no effect. If no <varname>ExecStart=</varname> is
-        specified, then the service must have <varname>RemainAfterExit=yes</varname> set.</para>
+        specified, then the service must have <varname>RemainAfterExit=yes</varname> and at least one
+        <varname>ExecStop=</varname> line set. (Services lacking both <varname>ExecStart=</varname> and
+        <varname>ExecStop=</varname> are not valid.)</para>
 
         <para>For each of the specified commands, the first argument must be an absolute path to an
         executable. Optionally, if this file name is prefixed with <literal>@</literal>, the second token will be