systemd-cat — Connect a pipeline or program's output with the journal
systemd-cat [OPTIONS...]  [COMMAND]  [ARGUMENTS...] 
systemd-cat [OPTIONS...] 
systemd-cat may be used to connect STDOUT and STDERR of a process with the journal, or as a filter tool in a shell pipeline to pass the output the previous pipeline element generates to the journal.
If no parameter is passed systemd-cat will write everything it reads from standard input (STDIN) to the journal.
If parameters are passed they are executed as command line with standard output (STDOUT) and standard error output (STDERR) connected to the journal, so that all it writes is stored in the journal.
The following options are understood:
-h, --help¶Prints a short help text and exits.
--version¶Prints a short version string and exits.
-t, --identifier=¶Specify a short string that is used to identify the logging tool. If not specified no identifying string is written to the journal.
-p, --priority=¶Specify the default
                                priority level for the logged
                                messages. Pass one of
                                emerg,
                                alert,
                                crit,
                                err,
                                warning,
                                notice,
                                info,
                                debug, or a
                                value between 0 and 7 (corresponding
                                to the same named levels). These
                                priority values are the same as
                                defined by
                                syslog(3). Defaults
                                to info. Note that
                                this simply controls the default,
                                individual lines may be logged with
                                different levels if they are prefixed
                                accordingly. For details see
                                --level-prefix=
                                below.
--level-prefix=¶Controls whether lines
                                read are parsed for syslog priority
                                level prefixes. If enabled (the
                                default) a line prefixed with a
                                priority prefix such as
                                <5> is logged
                                at priority 5
                                (notice), and
                                similar for the other priority
                                levels. Takes a boolean
                                argument.
Example 1. Invoke a program
This calls /bin/ls
                        with STDOUT/STDERR connected to the
                        journal:
# systemd-cat ls
Example 2. Usage in a shell pipeline
This builds a shell pipeline also
                        invoking /bin/ls and
                        writes the output it generates to the
                        journal:
# ls | systemd-cat
Even though the two examples have very similar effects the first is preferable since only one process is running at a time, and both STDOUT and STDERR are captured while in the second example only STDOUT is captured.