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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | EXAMPLES | SEE ALSO | COLOPHON |
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SYSTEMD-CAT(1) systemd-cat SYSTEMD-CAT(1)
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 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.
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
Print a short help text and exit.
--version
Print a short version string and exit.
-t, --identifier=
Specify a short string that is used to identify the logging
tool. If not specified, no identification string is set for
the journal entry, and the executable name (or "cat" if the
input is read from a pipe) will be used to describe the log
source instead.
-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.
--stderr-priority=
Specifies the default priority level for messages from the
process's standard error output (stderr). Usage of this option
is the same as the --priority= option, above, and both can be
used at once. When both are used, --priority= will specify the
default priority for standard output (stdout).
If --stderr-priority= is not specified, messages from stderr
will still be logged, with the same default priority level as
stdout.
Also, note that when stdout and stderr use the same default
priority, the messages will be strictly ordered, because one
channel is used for both. When the default priority differs,
two channels are used, and so stdout messages will not be
strictly ordered with respect to stderr messages - though they
will tend to be approximately ordered.
Added in version 241.
--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 similarly for the other priority levels. Takes
a boolean argument.
--namespace=
Specifies the journal namespace to which the standard IO
should be connected. For details about journal namespaces, see
systemd-journald.service(8).
Added in version 256.
On success, 0 is returned, a non-zero failure code otherwise.
Example 1. Invoke a program
This calls /bin/ls with standard output and error 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.
systemd(1), systemctl(1), logger(1)
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~rc2 SYSTEMD-CAT(1)
Pages that refer to this page: journalctl(1), sd-journal(3), systemd.directives(7), systemd.index(7), systemd-journald.service(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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