nixosTest: Add xclip as example of stdout blocker

1 files changed, 8 insertions, 3 deletions

diff --git a/nixos/doc/manual/from_md/development/writing-nixos-tests.section.xml b/nixos/doc/manual/from_md/development/writing-nixos-tests.section.xml
index e0fd90f2bac..0d523681b63 100644
--- a/nixos/doc/manual/from_md/development/writing-nixos-tests.section.xml
+++ b/nixos/doc/manual/from_md/development/writing-nixos-tests.section.xml
@@ -271,8 +271,13 @@ start_all()
           for this to consume all output reliably. This can be achieved
           by redirecting stdout to stderr <literal>&gt;&amp;2</literal>,
           to <literal>/dev/console</literal>,
-          <literal>/dev/null</literal> or a file. Takes an optional
-          parameter <literal>check_return</literal> that defaults to
+          <literal>/dev/null</literal> or a file. Examples of detaching
+          commands are <literal>sleep 365d &amp;</literal>, where the
+          shell forks a new process that can write to stdout and
+          <literal>xclip -i</literal>, where the
+          <literal>xclip</literal> command itself forks without closing
+          stdout. Takes an optional parameter
+          <literal>check_return</literal> that defaults to
           <literal>True</literal>. Setting this parameter to
           <literal>False</literal> will not check for the return code
           and return -1 instead. This can be used for commands that shut
@@ -314,7 +319,7 @@ start_all()
           <listitem>
             <para>
               It will wait for stdout to be closed. See
-              <literal>execute</literal>.
+              <literal>execute</literal> for the implications.
             </para>
           </listitem>
         </itemizedlist>