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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | FACILITIES AND LEVELS | CONFORMING TO | EXAMPLES | AUTHORS | SEE ALSO | AVAILABILITY | COLOPHON |
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LOGGER(1) User Commands LOGGER(1)
logger - enter messages into the system log
logger [options] [message]
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.
-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 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.
The logger utility exits 0 on success, and >0 if an error occurs.
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).
The logger command is expected to be IEEE Std 1003.2 ("POSIX.2")
compatible.
logger System rebooted
logger -p local0.notice -t HOSTIDM -f /dev/idmc
logger -n loghost.example.com System rebooted
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⟩.
journalctl(1), syslog(3), systemd.journal-fields(7)
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/⟩.
This page is part of the util-linux (a random collection of Linux
utilities) project. Information about the project can be found
at ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you
have a bug report for this manual page, send it to
util-linux@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
2020-12-18. (At that time, the date of the most recent commit
that was found in the repository was 2020-12-17.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
util-linux November 2015 LOGGER(1)
Pages that refer to this page: logger(1), pmie(1), pmpost(1), systemd-cat(1), syslog(3), rsyslog.conf(5), rsyslogd(8)
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