See also --server and --socket to specify where to connect.

Note that the system logging infrastructure (for example systemd when listening on /dev/log) may follow local socket credentials to overwrite the PID specified in the message. logger(1) is able to set those socket credentials to the given id, but only if you have root permissions and a process with the specified PID exists, otherwise the socket credentials are not modified and the problem is silently ignored.

logger --journald <<end
MESSAGE_ID=67feb6ffbaf24c5cbec13c008dd72309
MESSAGE=The dogs bark, but the caravan goes on.
DOGS=bark
CARAVAN=goes on
end

logger --journald=entry.txt

Notice that --journald will ignore values of other options, such as priority. If priority is needed it must be within input, and use PRIORITY field. The simple execution of journalctl(1) will display MESSAGE field. Use journalctl --output json-pretty to see rest of the fields.

To include newlines in MESSAGE, specify MESSAGE several times. This is handled as a special case, other fields will be stored as an array in the journal if they appear multiple times.

If the prefix contains no facility, the facility defaults to what is specified by the -p option. Similarly, if no prefix is provided, the line is logged using the priority given with -p.

This option doesn’t affect a command-line message.

The notq value suppresses the time-quality structured data from the submitted message. The time-quality information shows whether the local clock was synchronized plus the maximum number of microseconds the timestamp might be off. The time quality is also automatically suppressed when --sd-id timeQuality is specified.

The notime value (which implies notq) suppresses the complete sender timestamp that is in ISO-8601 format, including microseconds and timezone.

The nohost value suppresses gethostname(2) information from the message header.

The RFC 5424 protocol has been the default for logger since version 2.26.

logger currently generates the timeQuality standardized element only. RFC 5424 also describes the elements origin (with parameters ip, enterpriseId, software and swVersion) and meta (with parameters sequenceId, sysUpTime and language). These element IDs may be specified without the @digits suffix.

    logger --rfc5424 --sd-id zoo@123             \


                     --sd-param tiger="hungry"   \


                     --sd-param zebra="running"  \


                     --sd-id manager@123         \


                     --sd-param onMeeting="yes"  \


                     "this is message"

produces:

<13>1 2015-10-01T14:07:59.168662+02:00 ws kzak - - [timeQuality tzKnown="1" isSynced="1" syncAccuracy="218616"][zoo@123 tiger="hungry" zebra="running"][manager@123 onMeeting="yes"] this is message

Most receivers accept messages larger than 1KiB over any type of syslog protocol. As such, the --size option affects logger in all cases (not only when --rfc5424 was used).

Note: the message-size limit limits the overall message size, including the syslog header. Header sizes vary depending on the selected options and the hostname length. As a rule of thumb, headers are usually not longer than 50 to 80 characters. When selecting a maximum message size, it is important to ensure that the receiver supports the max size as well, otherwise messages may become truncated. Again, as a rule of thumb two to four KiB message size should generally be OK, whereas anything larger should be verified to work.

The default mode is auto. When errors are not enabled lost messages are not communicated and will result to successful exit status of logger(1) invocation.

See also --server and --socket to specify where to connect.

logger System rebooted

logger -p local0.notice -t HOSTIDM -f /dev/idmc

logger -n loghost.example.com System rebooted