− Connect a pipeline or program's output with the
[OPTIONS...] [COMMAND] [ARGUMENTS...]
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.
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
options are understood:
Print a short help text and
Print a short version string
Specify a short string that is
used to identify the logging tool. If not specified, no
identification string is written to the journal.
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
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.
On success, 0
is returned, a non−zero failure code otherwise.
Example 1. Invoke
/bin/ls with standard output and error connected to the
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 |
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.