<para>When both <option>--pipe</option> and <option>--pty</option> are used in combination the more appropriate
option is automatically determined and used. Specifically, when invoked with standard input, output and error
- connected to a TTY <option>--pty</option> is used, and otherwise <option>--pipe</option>.</para></listitem>
+ connected to a TTY <option>--pty</option> is used, and otherwise <option>--pipe</option>.</para>
+
+ <para>When this option is used the original file descriptors <command>systemd-run</command> receives are passed
+ to the service processes as-is. If the service runs with different privileges than
+ <command>systemd-run</command>, this means the service might not be able to re-open the passed file
+ descriptors, due to normal file descriptor access restrictions. If the invoked process is a shell script that
+ uses the <command>echo "hello" > /dev/stderr</command> construct for writing messages to stderr, this might
+ cause problems, as this only works if stderr can be re-opened. To mitigate this use the construct <command>echo
+ "hello" >&2</command> instead, which is mostly equivalent and avoids this pitfall.</para></listitem>
</varlistentry>
<varlistentry>