Ubuntu Manpage: logger - enter messages into the system log

Provided by: bsdutils_2.37.2-4ubuntu3.4_amd64

NAME

       logger - enter messages into the system log

SYNOPSIS

       logger [options] message

DESCRIPTION

       logger makes entries in the system log.

       When the optional message argument is present, it is written to the log. If it is not
       present, and the -f option is not given either, then standard input is logged.

OPTIONS

-d, --udp
Use datagrams (UDP) only. By default the connection is tried to the syslog port
defined in /etc/services, which is often 514.

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

-e, --skip-empty
Ignore empty lines when processing files. An empty line is defined to be a line
without any characters. Thus a line consisting only of whitespace is NOT considered
empty. Note that when the --prio-prefix option is specified, the priority is not part
of the line. Thus an empty line in this mode is a line that does not have any
characters after the priority prefix (e.g., <13>).

-f, --file file
Log the contents of the specified file. This option cannot be combined with a
command-line message.

-i
Log the PID of the logger process with each line.

--id[=id]
Log the PID of the logger process with each line. When the optional argument id is
specified, then it is used instead of the logger command’s PID. The use of --id=$$
(PPID) is recommended in scripts that send several messages.

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.

--journald[=file]
Write a systemd journal entry. The entry is read from the given file, when specified,
otherwise from standard input. Each line must begin with a field that is accepted by
journald; see systemd.journal-fields(7) for details. The use of a MESSAGE_ID field is
generally a good idea, as it makes finding entries easy. Examples:

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.

--msgid msgid
Sets the RFC 5424 <https://tools.ietf.org/html/rfc5424> MSGID field. Note that the
space character is not permitted inside of msgid. This option is only used if
--rfc5424 is specified as well; otherwise, it is silently ignored.

-n, --server server
Write to the specified remote syslog server instead of to the system log socket.
Unless --udp or --tcp is specified, logger will first try to use UDP, but if this
fails a TCP connection is attempted.

--no-act
Causes everything to be done except for writing the log message to the system log, and
removing the connection or the journal. This option can be used together with --stderr
for testing purposes.

--octet-count
Use the RFC 6587 <https://tools.ietf.org/html/rfc6587> octet counting framing method
for sending messages. When this option is not used, the default is no framing on UDP,
and RFC6587 non-transparent framing (also known as octet stuffing) on TCP.

-P, --port port
Use the specified port. When this option is not specified, the port defaults to syslog
for udp and to syslog-conn for tcp connections.

-p, --priority priority
Enter the message into the log with the specified priority. The priority may be
specified numerically or as a facility.level pair. For example, -p local3.info logs
the message as informational in the local3 facility. The default is user.notice.

--prio-prefix
Look for a syslog prefix on every line read from standard input. This prefix is a
decimal number within angle brackets that encodes both the facility and the level. The
number is constructed by multiplying the facility by 8 and then adding the level. For
example, local0.info, meaning facility=16 and level=6, becomes <134>.

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.

--rfc3164
Use the RFC 3164 <https://tools.ietf.org/html/rfc3164> BSD syslog protocol to submit
messages to a remote server.

--rfc5424[=without]
Use the RFC 5424 <https://tools.ietf.org/html/rfc5424> syslog protocol to submit
messages to a remote server. The optional without argument can be a comma-separated
list of the following values: notq, notime, nohost.

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.

-s, --stderr
Output the message to standard error as well as to the system log.

--sd-id name[@digits]
Specifies a structured data element ID for an RFC 5424 message header. The option has
to be used before --sd-param to introduce a new element. The number of structured data
elements is unlimited. The ID (name plus possibly @digits) is case-sensitive and
uniquely identifies the type and purpose of the element. The same ID must not exist
more than once in a message. The @digits part is required for user-defined
non-standardized IDs.

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.

--sd-param name=value
Specifies a structured data element parameter, a name and value pair. The option has
to be used after --sd-id and may be specified more than once for the same element.
Note that the quotation marks around value are required and must be escaped on the
command line.

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

-S, --size size
Sets the maximum permitted message size to size. The default is 1KiB characters, which
is the limit traditionally used and specified in RFC 3164. With RFC 5424, this limit
has become flexible. A good assumption is that RFC 5424 receivers can at least process
4KiB messages.

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.

--socket-errors[=mode]
Print errors about Unix socket connections. The mode can be a value of off, on, or
auto. When the mode is auto, then logger will detect if the init process is
systemd(1), and if so assumption is made /dev/log can be used early at boot. Other
init systems lack of /dev/log will not cause errors that is identical with messaging
using openlog(3) system call. The logger(1) before version 2.26 used openlog, and
hence was unable to detected loss of messages sent to Unix sockets.

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.

-T, --tcp
Use stream (TCP) only. By default the connection is tried to the syslog-conn port
defined in /etc/services, which is often 601.

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

-t, --tag tag
Mark every line to be logged with the specified tag. The default tag is the name of
the user logged in on the terminal (or a user name based on effective user ID).

-u, --socket socket
Write to the specified socket instead of to the system log socket.

--
End the argument list. This allows the message to start with a hyphen (-).

-V, --version
Display version information and exit.

-h, --help
Display help text and exit.

EXIT STATUS

       The logger utility exits 0 on success, and >0 if an error occurs.

FACILITIES AND LEVELS

       Valid facility names are:

       auth
       authpriv for security information of a sensitive nature
       cron

       daemon
       ftp
       kern cannot be generated from userspace process, automatically converted to user

       lpr
       mail
       news
       syslog
       user
       uucp
       local0
       to
       local7
       security deprecated synonym for auth

       Valid level names are:

       emerg
       alert
       crit
       err
       warning
       notice
       info
       debug
       panic deprecated synonym for emerg
       error deprecated synonym for err
       warn deprecated synonym for warning

       For the priority order and intended purposes of these facilities and levels, see
       syslog(3).

CONFORMING TO

       The logger command is expected to be IEEE Std 1003.2 ("POSIX.2") compatible.

EXAMPLES

       logger System rebooted logger -p local0.notice -t HOSTIDM -f /dev/idmc logger -n
       loghost.example.com System rebooted

AUTHORS

       The logger command was originally written by University of California in 1983-1993 and
       later rewritten by Karel Zak <kzak@redhat.com>, Rainer Gerhards <rgerhards@adiscon.com>,
       and Sami Kerola <kerolasa@iki.fi>.

REPORTING BUGS

       For bug reports, use the issue tracker at https://github.com/karelzak/util-linux/issues.

AVAILABILITY

       The logger command is part of the util-linux package which can be downloaded from Linux
       Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.