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 the
21 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 defined
27 to be a line without any characters. Thus a line consisting only of
28 whitespace is NOT considered empty. Note that when the
29 --prio-prefix option is specified, the priority is not part of the
30 line. Thus an empty line in this mode is a line that does not have
31 any characters after the priority prefix (e.g., <13>).
32 -f, --file file
34 Log the contents of the specified file. This option cannot be
35 combined with a command-line message.
36 -i
38 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 optional
42 argument id is specified, then it is used instead of the logger
43 command’s PID. The use of --id=$$ (PPID) is recommended in scripts
44 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 to
48 overwrite the PID specified in the message. logger(1) is able to
49 set those socket credentials to the given id, but only if you have
50 root permissions and a process with the specified PID exists,
51 otherwise the socket credentials are not modified and the problem
52 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 must
57 begin with a field that is accepted by journald; see
58 systemd.journal-fields(7) for details. The use of a MESSAGE_ID
59 field is generally a good idea, as it makes finding entries easy.
60 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 as
72 priority. If priority is needed it must be within input, and use
73 PRIORITY field. The simple execution of journalctl(1) will display
74 MESSAGE field. Use journalctl --output json-pretty to see rest of
75 the fields.
76 To include newlines in MESSAGE, specify MESSAGE several times. This
78 is handled as a special case, other fields will be stored as an
79 array in the journal if they appear multiple times.
80 --msgid msgid
82 Sets the RFC 5424 <https://tools.ietf.org/html/rfc5424> MSGID
83 field. Note that the space character is not permitted inside of
84 msgid. This option is only used if --rfc5424 is specified as well;
85 otherwise, it is silently ignored.
86 -n, --server server
88 Write to the specified remote syslog server instead of to the
89 system log socket. Unless --udp or --tcp is specified, logger will
90 first try to use UDP, but if this fails a TCP connection is
91 attempted.
92 --no-act
94 Causes everything to be done except for writing the log message to
95 the system log, and removing the connection to the journal. This
96 option can be used together with --stderr for testing purposes.
97 --octet-count
99 Use the RFC 6587 <https://tools.ietf.org/html/rfc6587> octet
100 counting framing method for sending messages. When this option is
101 not used, the default is no framing on UDP, and RFC6587
102 non-transparent framing (also known as octet stuffing) on TCP.
103 -P, --port port
105 Use the specified port. When this option is not specified, the port
106 defaults to syslog for udp and to syslog-conn for tcp connections.
107 -p, --priority priority
109 Enter the message into the log with the specified priority. The
110 priority may be specified numerically or as a facility.level pair.
111 For example, -p local3.info logs the message as informational in
112 the local3 facility. The default is user.notice.
113 --prio-prefix
115 Look for a syslog prefix on every line read from standard input.
116 This prefix is a decimal number within angle brackets that encodes
117 both the facility and the level. The number is constructed by
118 multiplying the facility by 8 and then adding the level. For
119 example, local0.info, meaning facility=16 and level=6, becomes
120 <134>.
121 If the prefix contains no facility, the facility defaults to what
123 is specified by the -p option. Similarly, if no prefix is provided,
124 the line is logged using the priority given with -p.
125 This option doesn’t affect a command-line message.
127 --rfc3164
129 Use the RFC 3164 <https://tools.ietf.org/html/rfc3164> BSD syslog
130 protocol to submit messages to a remote server.
131 --rfc5424[=without]
133 Use the RFC 5424 <https://tools.ietf.org/html/rfc5424> syslog
134 protocol to submit messages to a remote server. The optional
135 without argument can be a comma-separated list of the following
136 values: notq, notime, nohost.
137 The notq value suppresses the time-quality structured data from the
139 submitted message. The time-quality information shows whether the
140 local clock was synchronized plus the maximum number of
141 microseconds the timestamp might be off. The time quality is also
142 automatically suppressed when --sd-id timeQuality is specified.
143 The notime value (which implies notq) suppresses the complete
145 sender timestamp that is in ISO-8601 format, including microseconds
146 and timezone.
147 The nohost value suppresses gethostname(2) information from the
149 message header.
150 The RFC 5424 protocol has been the default for logger since version
152 2.26.
153 -s, --stderr
155 Output the message to standard error as well as to the system log.
156 --sd-id name[@digits]
158 Specifies a structured data element ID for an RFC 5424 message
159 header. The option has to be used before --sd-param to introduce a
160 new element. The number of structured data elements is unlimited.
161 The ID (name plus possibly @digits) is case-sensitive and uniquely
162 identifies the type and purpose of the element. The same ID must
163 not exist more than once in a message. The @digits part is required
164 for user-defined non-standardized IDs.
165 logger currently generates the timeQuality standardized element
167 only. RFC 5424 also describes the elements origin (with parameters
168 ip, enterpriseId, software and swVersion) and meta (with parameters
169 sequenceId, sysUpTime and language). These element IDs may be
170 specified without the @digits suffix.
171 --sd-param name=value
173 Specifies a structured data element parameter, a name and value
174 pair. The option has to be used after --sd-id and may be specified
175 more than once for the same element. Note that the quotation marks
176 around value are required and must be escaped on the 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
188 tzKnown="1" isSynced="1" syncAccuracy="218616"][zoo@123
189 tiger="hungry" zebra="running"][manager@123 onMeeting="yes"] this
190 is message
191 -S, --size size
193 Sets the maximum permitted message size to size. The default is
194 1KiB characters, which is the limit traditionally used and
195 specified in RFC 3164. With RFC 5424, this limit has become
196 flexible. A good assumption is that RFC 5424 receivers can at least
197 process 4KiB messages.
198 Most receivers accept messages larger than 1KiB over any type of
200 syslog protocol. As such, the --size option affects logger in all
201 cases (not only when --rfc5424 was used).
202 Note: the message-size limit limits the overall message size,
204 including the syslog header. Header sizes vary depending on the
205 selected options and the hostname length. As a rule of thumb,
206 headers are usually not longer than 50 to 80 characters. When
207 selecting a maximum message size, it is important to ensure that
208 the receiver supports the max size as well, otherwise messages may
209 become truncated. Again, as a rule of thumb two to four KiB message
210 size should generally be OK, whereas anything larger should be
211 verified to work.
212 --socket-errors[=mode]
214 Print errors about Unix socket connections. The mode can be a value
215 of off, on, or auto. When the mode is auto, then logger will detect
216 if the init process is systemd(1), and if so assumption is made
217 /dev/log can be used early at boot. Other init systems lack of
218 /dev/log will not cause errors that is identical with messaging
219 using openlog(3) system call. The logger(1) before version 2.26
220 used openlog(3), and hence was unable to detected loss of messages
221 sent to Unix sockets.
222 The default mode is auto. When errors are not enabled lost messages
224 are not communicated and will result to successful exit status of
225 logger(1) invocation.
226 -T, --tcp
228 Use stream (TCP) only. By default the connection is tried to the
229 syslog-conn port defined in /etc/services, which is often 601.
230 See also --server and --socket to specify where to connect.
232 -t, --tag tag
234 Mark every line to be logged with the specified tag. The default
235 tag is the name of the user logged in on the terminal (or a user
236 name based on effective user ID).
237 -u, --socket socket
239 Write to the specified socket instead of to the system log socket.
240 --
242 End the argument list. This allows the message to start with a
243 hyphen (-).
244 -h, --help
246 Display help text and exit.
247 -V, --version
249 Print version and exit.
250
252 The logger utility exits 0 on success, and >0 if an error occurs.
253
255 Valid facility names are:
256 auth
258 authpriv for security information of a sensitive nature
259 cron
260 daemon
262 ftp
263 kern cannot be generated from userspace process, automatically
264 converted to user
265 lpr
267 mail
268 news
269 syslog
270 user
271 uucp
272 local0
273 to
274 local7
275 security deprecated synonym for auth
276 Valid level names are:
278 emerg
280 alert
281 crit
282 err
283 warning
284 notice
285 info
286 debug
287 panic deprecated synonym for emerg
288 error deprecated synonym for err
289 warn deprecated synonym for warning
290 For the priority order and intended purposes of these facilities and
292 levels, see syslog(3).
293
295 The logger command is expected to be IEEE Std 1003.2 ("POSIX.2")
296 compatible.
297
299 logger System rebooted
300 logger -p local0.notice -t HOSTIDM -f /dev/idmc
302 logger -n loghost.example.com System rebooted
304
306 The logger command was originally written by University of California
307 in 1983-1993 and later rewritten by Karel Zak <kzak@redhat.com>, Rainer
308 Gerhards <rgerhards@adiscon.com>, and Sami Kerola <kerolasa@iki.fi>.
309
311 journalctl(1), syslog(3), systemd.journal-fields(7)
312
314 For bug reports, use the issue tracker at
315 https://github.com/util-linux/util-linux/issues.
316
318 The logger command is part of the util-linux package which can be
319 downloaded from Linux Kernel Archive
320 <https://www.kernel.org/pub/linux/utils/util-linux/>.
321util-linux 2.39.2 2023-06-14 LOGGER(1)