Ubuntu Manpage: logger - enter messages into the system log

Provided by: bsdutils_2.34-0.1ubuntu9.6_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 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 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 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 BSD syslog protocol to submit messages to a remote server.

--rfc5424[=without]
Use the RFC 5424 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 logger will detect if the init process is systemd, 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 return value 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.

RETURN VALUE

       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).

EXAMPLES

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

STANDARDS

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

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⟩.

AVAILABILITY

       The logger command is part of the util-linux package and is available  from  Linux  Kernel
       Archive ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩.