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 -e, --skip-empty
24 Ignore empty lines when processing files. An empty line is
25 defined to be a line without any characters. Thus a line con‐
26 sisting only of whitespace is NOT considered empty. Note that
27 when the --prio-prefix option is specified, the priority is not
28 part of the line. Thus an empty line in this mode is a line
29 that does not have any characters after the priority prefix
30 (e.g. <13>).
31 -f, --file file
33 Log the contents of the specified file. This option cannot be
34 combined with a command-line message.
35 -i Log the PID of the logger process with each line.
37 --id[=id]
39 Log the PID of the logger process with each line. When the
40 optional argument id is specified, then it is used instead of
41 the logger command's PID. The use of --id=$$ (PPID) is recom‐
42 mended in scripts that send several messages.
43 Note that the system logging infrastructure (for example systemd
45 when listening on /dev/log) may follow local socket credentials
46 to overwrite the PID specified in the message. logger(1) is
47 able to set those socket credentials to the given id, but only
48 if you have root permissions and a process with the specified
49 PID exists, otherwise the socket credentials are not modified
50 and the problem is silently ignored.
51 --journald[=file]
53 Write a systemd journal entry. The entry is read from the given
54 file, when specified, otherwise from standard input. Each line
55 must begin with a field that is accepted by journald; see sys‐
56 temd.journal-fields(7) for details. The use of a MESSAGE_ID
57 field is generally a good idea, as it makes finding entries
58 easy. Examples:
59 logger --journald <<end
61 MESSAGE_ID=67feb6ffbaf24c5cbec13c008dd72309
62 MESSAGE=The dogs bark, but the caravan goes on.
63 DOGS=bark
64 CARAVAN=goes on
65 end
66 logger --journald=entry.txt
68 Notice that --journald will ignore values of other options, such
70 as priority. If priority is needed it must be within input, and
71 use PRIORITY field. The simple execution of journalctl will
72 display MESSAGE field. Use journalctl --output json-pretty to
73 see rest of the fields.
74 --msgid msgid
76 Sets the RFC5424 MSGID field. Note that the space character is
77 not permitted inside of msgid. This option is only used if
78 --rfc5424 is specified as well; otherwise, it is silently
79 ignored.
80 -n, --server server
82 Write to the specified remote syslog server instead of to the
83 system log socket. Unless --udp or --tcp is specified, logger
84 will first try to use UDP, but if this fails a TCP connection is
85 attempted.
86 --no-act
88 Causes everything to be done except for writing the log message
89 to the system log, and removing the connection or the journal.
90 This option can be used together with --stderr for testing pur‐
91 poses.
92 --octet-count
94 Use the RFC 6587 octet counting framing method for sending mes‐
95 sages. When this option is not used, the default is no framing
96 on UDP, and RFC6587 non-transparent framing (also known as octet
97 stuffing) on TCP.
98 -P, --port port
100 Use the specified port. When this option is not specified, the
101 port defaults to syslog for udp and to syslog-conn for tcp con‐
102 nections.
103 -p, --priority priority
105 Enter the message into the log with the specified priority. The
106 priority may be specified numerically or as a facility.level
107 pair. For example, -p local3.info logs the message as informa‐
108 tional in the local3 facility. The default is user.notice.
109 --prio-prefix
111 Look for a syslog prefix on every line read from standard input.
112 This prefix is a decimal number within angle brackets that
113 encodes both the facility and the level. The number is con‐
114 structed by multiplying the facility by 8 and then adding the
115 level. For example, local0.info, meaning facility=16 and
116 level=6, becomes <134>.
117 If the prefix contains no facility, the facility defaults to
119 what is specified by the -p option. Similarly, if no prefix is
120 provided, the line is logged using the priority given with -p.
121 This option doesn't affect a command-line message.
123 --rfc3164
125 Use the RFC 3164 BSD syslog protocol to submit messages to a
126 remote server.
127 --rfc5424[=without]
129 Use the RFC 5424 syslog protocol to submit messages to a remote
130 server. The optional without argument can be a comma-separated
131 list of the following values: notq, notime, nohost.
132 The notq value suppresses the time-quality structured data from
134 the submitted message. The time-quality information shows
135 whether the local clock was synchronized plus the maximum number
136 of microseconds the timestamp might be off. The time quality is
137 also automatically suppressed when --sd-id timeQuality is speci‐
138 fied.
139 The notime value (which implies notq) suppresses the complete
141 sender timestamp that is in ISO-8601 format, including microsec‐
142 onds and timezone.
143 The nohost value suppresses gethostname(2) information from the
145 message header.
146 The RFC 5424 protocol has been the default for logger since ver‐
148 sion 2.26.
149 -s, --stderr
151 Output the message to standard error as well as to the system
152 log.
153 --sd-id name[@digits]
155 Specifies a structured data element ID for an RFC 5424 message
156 header. The option has to be used before --sd-param to intro‐
157 duce a new element. The number of structured data elements is
158 unlimited. The ID (name plus possibly @digits) is case-sensi‐
159 tive and uniquely identifies the type and purpose of the ele‐
160 ment. The same ID must not exist more than once in a message.
161 The @digits part is required for user-defined non-standardized
162 IDs.
163 logger currently generates the timeQuality standardized element
165 only. RFC 5424 also describes the elements origin (with parame‐
166 ters ip, enterpriseId, software and swVersion) and meta (with
167 parameters sequenceId, sysUpTime and language). These element
168 IDs may be specified without the @digits suffix.
169 --sd-param name="value"
172 Specifies a structured data element parameter, a name and value
173 pair. The option has to be used after --sd-id and may be speci‐
174 fied more than once for the same element. Note that the quota‐
175 tion marks around value are required and must be escaped on the
176 command line.
177 logger --rfc5424 --sd-id zoo@123 \
179 --sd-param tiger=\"hungry\" \
180 --sd-param zebra=\"running\" \
181 --sd-id manager@123 \
182 --sd-param onMeeting=\"yes\" \
183 "this is message"
184 produces:
186 <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
188 -S, --size size
190 Sets the maximum permitted message size to size. The default is
191 1KiB characters, which is the limit traditionally used and spec‐
192 ified in RFC 3164. With RFC 5424, this limit has become flexi‐
193 ble. A good assumption is that RFC 5424 receivers can at least
194 process 4KiB messages.
195 Most receivers accept messages larger than 1KiB over any type of
197 syslog protocol. As such, the --size option affects logger in
198 all cases (not only when --rfc5424 was used).
199 Note: the message-size limit limits the overall message size,
201 including the syslog header. Header sizes vary depending on the
202 selected options and the hostname length. As a rule of thumb,
203 headers are usually not longer than 50 to 80 characters. When
204 selecting a maximum message size, it is important to ensure that
205 the receiver supports the max size as well, otherwise messages
206 may become truncated. Again, as a rule of thumb two to four KiB
207 message size should generally be OK, whereas anything larger
208 should be verified to work.
209 --socket-errors[=mode]
212 Print errors about Unix socket connections. The mode can be a
213 value of off, on, or auto. When the mode is auto logger will
214 detect if the init process is systemd, and if so assumption is
215 made /dev/log can be used early at boot. Other init systems
216 lack of /dev/log will not cause errors that is identical with
217 messaging using openlog(3) system call. The logger(1) before
218 version 2.26 used openlog, and hence was unable to detected loss
219 of messages sent to Unix sockets.
220 The default mode is auto. When errors are not enabled lost mes‐
222 sages are not communicated and will result to successful return
223 value of logger(1) invocation.
224 -T, --tcp
226 Use stream (TCP) only. By default the connection is tried to
227 the syslog-conn port defined in /etc/services, which is often
228 601.
229 -t, --tag tag
231 Mark every line to be logged with the specified tag. The
232 default tag is the name of the user logged in on the terminal
233 (or a user name based on effective user ID).
234 -u, --socket socket
236 Write to the specified socket instead of to the system log
237 socket.
238 -- End the argument list. This allows the message to start with a
240 hyphen (-).
241 -V, --version
243 Display version information and exit.
244 -h, --help
246 Display help text and exit.
247
249 The logger utility exits 0 on success, and >0 if an error occurs.
250
252 Valid facility names are:
253 auth
255 authpriv for security information of a sensitive nature
256 cron
257 daemon
258 ftp
259 kern cannot be generated from userspace process, automatically converted to user
260 lpr
261 mail
262 news
263 syslog
264 user
266 uucp
267 local0
268 to
269 local7
270 security deprecated synonym for auth
271 Valid level names are:
273 emerg
275 alert
276 crit
277 err
278 warning
279 notice
280 info
281 debug
282 panic deprecated synonym for emerg
283 error deprecated synonym for err
284 warn deprecated synonym for warning
285 For the priority order and intended purposes of these facilities and
287 levels, see syslog(3).
288
290 logger System rebooted
291 logger -p local0.notice -t HOSTIDM -f /dev/idmc
292 logger -n loghost.example.com System rebooted
293
295 journalctl(1), syslog(3), systemd.journal-fields(7)
296
298 The logger command is expected to be IEEE Std 1003.2 ("POSIX.2") com‐
299 patible.
300
302 The logger command is part of the util-linux package and is available
303 from Linux Kernel Archive ⟨https://www.kernel.org/pub/linux/utils/util-
304 linux/⟩.
305util-linux November 2015 LOGGER(1)