The first paragraph of the description of the systemd-cat utility incorrectly referred to stdin when it obviously meant stderr: the other fd that it connects to the journal via a unix(7) domain socket, as clarified in the following paragraphs.
I've also replaced "process" with "command" as in that mode, systemd-cat executes a file and does not spawn a process.
<title>Description</title>
<para><command>systemd-cat</command> may be used to connect the
- standard input and output of a process to the journal, or as a
- filter tool in a shell pipeline to pass the output the previous
- pipeline element generates to the journal.</para>
+ standard output and error output of a command to the journal, or
+ as a filter tool in a shell pipeline to pass the output the
+ previous pipeline element generates to the journal.</para>
<para>If no parameter is passed, <command>systemd-cat</command>
will write everything it reads from standard input (stdin) to the