logger

LOGGER(1)                        User Commands                       LOGGER(1)

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>.

SEE ALSO
       journalctl(1), syslog(3), systemd.journal-fields(7)

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/>.

util-linux 2.37.2                 2021-06-02                         LOGGER(1)