man: mention that systemctl is-active or is-failed do not load units

See the discussion in the issue #7875.

diff --git a/man/systemctl.xml b/man/systemctl.xml
index 60882e5..375b91a 100644 (file)
--- a/man/systemctl.xml
+++ b/man/systemctl.xml
@@ -877,6 +877,10 @@ Sun 2017-02-26 20:57:49 EST  2h 3min left  Sun 2017-02-26 11:56:36 EST  6h ago
             non-zero otherwise. Unless <option>--quiet</option> is
             specified, this will also print the current unit state to
             standard output.</para>
+
+            <para>Unlike <command>status</command> or <command>show</command> commands, this does not
+            load units. So, when a specified unit is an alias of another unit and is not loaded,
+            then this outputs "inactive", even if the aliased unit is active.</para>
           </listitem>
         </varlistentry>
         <varlistentry>
@@ -889,6 +893,10 @@ Sun 2017-02-26 20:57:49 EST  2h 3min left  Sun 2017-02-26 11:56:36 EST  6h ago
             non-zero otherwise. Unless <option>--quiet</option> is
             specified, this will also print the current unit state to
             standard output.</para>
+
+            <para>Unlike <command>status</command> or <command>show</command> commands, this does not
+            load units. So, when a specified unit is an alias of another unit and is not loaded,
+            then this outputs "inactive", even if the aliased unit is failed.</para>
           </listitem>
         </varlistentry>
         <varlistentry>
@@ -987,6 +995,9 @@ Jan 12 10:46:45 example.com bluetoothd[8900]: gatt-time-server: Input/output err
             are always exposed as properties ending in the <literal>…USec</literal> suffix even if a matching
             configuration options end in <literal>…Sec</literal>, because microseconds is the normalized time unit used
             by the system and service manager.</para>
+
+            <para>As similar to <command>status</command> command, systemd implicitly loads units as necessary.
+            See also <command>status</command> command for the detail.</para>
           </listitem>
         </varlistentry>
         <varlistentry>