1LOGGER(1) User Commands LOGGER(1)
2
6 logger - enter messages into the system log
7
9 logger [options] [message]
10
12 logger makes entries in the system log.
13 When the optional message argument is present, it is written to the
15 log. If it is not present, and the -f option is not given either, then
16 standard input is logged.
17
19 -d, --udp
20 Use datagrams (UDP) only. By default the connection is tried to
21 the syslog port defined in /etc/services, which is often 514 .
22 See also --server and --socket to specify where to connect.
24 -e, --skip-empty
26 Ignore empty lines when processing files. An empty line is
27 defined to be a line without any characters. Thus a line con‐
28 sisting only of whitespace is NOT considered empty. Note that
29 when the --prio-prefix option is specified, the priority is not
30 part of the line. Thus an empty line in this mode is a line
31 that does not have any characters after the priority prefix
32 (e.g. <13>).
33 -f, --file file
35 Log the contents of the specified file. This option cannot be
36 combined with a command-line message.
37 -i Log the PID of the logger process with each line.
39 --id[=id]
41 Log the PID of the logger process with each line. When the
42 optional argument id is specified, then it is used instead of
43 the logger command's PID. The use of --id=$$ (PPID) is recom‐
44 mended in scripts that send several messages.
45 Note that the system logging infrastructure (for example systemd
47 when listening on /dev/log) may follow local socket credentials
48 to overwrite the PID specified in the message. logger(1) is
49 able to set those socket credentials to the given id, but only
50 if you have root permissions and a process with the specified
51 PID exists, otherwise the socket credentials are not modified
52 and the problem is silently ignored.
53 --journald[=file]
55 Write a systemd journal entry. The entry is read from the given
56 file, when specified, otherwise from standard input. Each line
57 must begin with a field that is accepted by journald; see sys‐
58 temd.journal-fields(7) for details. The use of a MESSAGE_ID
59 field is generally a good idea, as it makes finding entries
60 easy. Examples:
61 logger --journald <<end
63 MESSAGE_ID=67feb6ffbaf24c5cbec13c008dd72309
64 MESSAGE=The dogs bark, but the caravan goes on.
65 DOGS=bark
66 CARAVAN=goes on
67 end
68 logger --journald=entry.txt
70 Notice that --journald will ignore values of other options, such
72 as priority. If priority is needed it must be within input, and
73 use PRIORITY field. The simple execution of journalctl will
74 display MESSAGE field. Use journalctl --output json-pretty to
75 see rest of the fields.
76 --msgid msgid
78 Sets the RFC5424 MSGID field. Note that the space character is
79 not permitted inside of msgid. This option is only used if
80 --rfc5424 is specified as well; otherwise, it is silently
81 ignored.
82 -n, --server server
84 Write to the specified remote syslog server instead of to the
85 system log socket. Unless --udp or --tcp is specified, logger
86 will first try to use UDP, but if this fails a TCP connection is
87 attempted.
88 --no-act
90 Causes everything to be done except for writing the log message
91 to the system log, and removing the connection or the journal.
92 This option can be used together with --stderr for testing pur‐
93 poses.
94 --octet-count
96 Use the RFC 6587 octet counting framing method for sending mes‐
97 sages. When this option is not used, the default is no framing
98 on UDP, and RFC6587 non-transparent framing (also known as octet
99 stuffing) on TCP.
100 -P, --port port
102 Use the specified port. When this option is not specified, the
103 port defaults to syslog for udp and to syslog-conn for tcp con‐
104 nections.
105 -p, --priority priority
107 Enter the message into the log with the specified priority. The
108 priority may be specified numerically or as a facility.level
109 pair. For example, -p local3.info logs the message as informa‐
110 tional in the local3 facility. The default is user.notice.
111 --prio-prefix
113 Look for a syslog prefix on every line read from standard input.
114 This prefix is a decimal number within angle brackets that
115 encodes both the facility and the level. The number is con‐
116 structed by multiplying the facility by 8 and then adding the
117 level. For example, local0.info, meaning facility=16 and
118 level=6, becomes <134>.
119 If the prefix contains no facility, the facility defaults to
121 what is specified by the -p option. Similarly, if no prefix is
122 provided, the line is logged using the priority given with -p.
123 This option doesn't affect a command-line message.
125 --rfc3164
127 Use the RFC 3164 BSD syslog protocol to submit messages to a
128 remote server.
129 --rfc5424[=without]
131 Use the RFC 5424 syslog protocol to submit messages to a remote
132 server. The optional without argument can be a comma-separated
133 list of the following values: notq, notime, nohost.
134 The notq value suppresses the time-quality structured data from
136 the submitted message. The time-quality information shows
137 whether the local clock was synchronized plus the maximum number
138 of microseconds the timestamp might be off. The time quality is
139 also automatically suppressed when --sd-id timeQuality is speci‐
140 fied.
141 The notime value (which implies notq) suppresses the complete
143 sender timestamp that is in ISO-8601 format, including microsec‐
144 onds and timezone.
145 The nohost value suppresses gethostname(2) information from the
147 message header.
148 The RFC 5424 protocol has been the default for logger since ver‐
150 sion 2.26.
151 -s, --stderr
153 Output the message to standard error as well as to the system
154 log.
155 --sd-id name[@digits]
157 Specifies a structured data element ID for an RFC 5424 message
158 header. The option has to be used before --sd-param to intro‐
159 duce a new element. The number of structured data elements is
160 unlimited. The ID (name plus possibly @digits) is case-sensi‐
161 tive and uniquely identifies the type and purpose of the ele‐
162 ment. The same ID must not exist more than once in a message.
163 The @digits part is required for user-defined non-standardized
164 IDs.
165 logger currently generates the timeQuality standardized element
167 only. RFC 5424 also describes the elements origin (with parame‐
168 ters ip, enterpriseId, software and swVersion) and meta (with
169 parameters sequenceId, sysUpTime and language). These element
170 IDs may be specified without the @digits suffix.
171 --sd-param name="value"
174 Specifies a structured data element parameter, a name and value
175 pair. The option has to be used after --sd-id and may be speci‐
176 fied more than once for the same element. Note that the quota‐
177 tion marks around value are required and must be escaped on the
178 command line.
179 logger --rfc5424 --sd-id zoo@123 \
181 --sd-param tiger=\"hungry\" \
182 --sd-param zebra=\"running\" \
183 --sd-id manager@123 \
184 --sd-param onMeeting=\"yes\" \
185 "this is message"
186 produces:
188 <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
190 -S, --size size
192 Sets the maximum permitted message size to size. The default is
193 1KiB characters, which is the limit traditionally used and spec‐
194 ified in RFC 3164. With RFC 5424, this limit has become flexi‐
195 ble. A good assumption is that RFC 5424 receivers can at least
196 process 4KiB messages.
197 Most receivers accept messages larger than 1KiB over any type of
199 syslog protocol. As such, the --size option affects logger in
200 all cases (not only when --rfc5424 was used).
201 Note: the message-size limit limits the overall message size,
203 including the syslog header. Header sizes vary depending on the
204 selected options and the hostname length. As a rule of thumb,
205 headers are usually not longer than 50 to 80 characters. When
206 selecting a maximum message size, it is important to ensure that
207 the receiver supports the max size as well, otherwise messages
208 may become truncated. Again, as a rule of thumb two to four KiB
209 message size should generally be OK, whereas anything larger
210 should be verified to work.
211 --socket-errors[=mode]
214 Print errors about Unix socket connections. The mode can be a
215 value of off, on, or auto. When the mode is auto logger will
216 detect if the init process is systemd, and if so assumption is
217 made /dev/log can be used early at boot. Other init systems
218 lack of /dev/log will not cause errors that is identical with
219 messaging using openlog(3) system call. The logger(1) before
220 version 2.26 used openlog, and hence was unable to detected loss
221 of messages sent to Unix sockets.
222 The default mode is auto. When errors are not enabled lost mes‐
224 sages are not communicated and will result to successful return
225 value of logger(1) invocation.
226 -T, --tcp
228 Use stream (TCP) only. By default the connection is tried to
229 the syslog-conn port defined in /etc/services, which is often
230 601.
231 See also --server and --socket to specify where to connect.
233 -t, --tag tag
235 Mark every line to be logged with the specified tag. The
236 default tag is the name of the user logged in on the terminal
237 (or a user name based on effective user ID).
238 -u, --socket socket
240 Write to the specified socket instead of to the system log
241 socket.
242 -- End the argument list. This allows the message to start with a
244 hyphen (-).
245 -V, --version
247 Display version information and exit.
248 -h, --help
250 Display help text and exit.
251
253 The logger utility exits 0 on success, and >0 if an error occurs.
254
256 Valid facility names are:
257 auth
259 authpriv for security information of a sensitive nature
260 cron
261 daemon
262 ftp
263 kern cannot be generated from userspace process, automati‐
266 cally converted to user
267 lpr
268 mail
269 news
270 syslog
271 user
272 uucp
273 local0
274 to
275 local7
276 security deprecated synonym for auth
277 Valid level names are:
279 emerg
281 alert
282 crit
283 err
284 warning
285 notice
286 info
287 debug
288 panic deprecated synonym for emerg
289 error deprecated synonym for err
290 warn deprecated synonym for warning
291 For the priority order and intended purposes of these facilities and
293 levels, see syslog(3).
294
296 logger System rebooted
297 logger -p local0.notice -t HOSTIDM -f /dev/idmc
298 logger -n loghost.example.com System rebooted
299
301 journalctl(1), syslog(3), systemd.journal-fields(7)
302
304 The logger command is expected to be IEEE Std 1003.2 ("POSIX.2") com‐
305 patible.
306
308 The logger command is part of the util-linux package and is available
309 from Linux Kernel Archive ⟨https://www.kernel.org/pub/linux/utils/util-
310 linux/⟩.
311util-linux November 2015 LOGGER(1)