8 lttng-enable-event - Create or enable LTTng recording event rules
13 Create or enable one or more recording event rules to match Linux kernel
14 tracepoint or system call events:
17 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *enable-event* option:--kernel [option:--tracepoint | option:--syscall]
18 (option:--all | 'NAME'[,'NAME']...) [option:--filter='EXPR']
19 [option:--session='SESSION'] [option:--channel='CHANNEL']
21 Create or enable a recording event rule to match Linux kernel events
22 created from a dynamic instrumentation point:
25 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *enable-event* option:--kernel
26 (option:--probe='LOC' | option:--function='LOC' | option:--userspace-probe='LOC') 'RECORDNAME'
27 [option:--session='SESSION'] [option:--channel='CHANNEL']
29 Create or enable one or more recording event rules to match
30 user space tracepoint events:
33 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *enable-event* option:--userspace [option:--tracepoint]
34 (option:--all | 'NAME'[,'NAME']...) [option:--exclude='XNAME'[,'XNAME']...]
35 [option:--loglevel='LOGLEVEL' | option:--loglevel-only='LOGLEVEL'] [option:--filter='EXPR']
36 [option:--session='SESSION'] [option:--channel='CHANNEL']
38 Create or enable one or more recording event rules to match
39 Java/Python logging events:
42 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *enable-event* (option:--jul | option:--log4j | option:--python)
43 [option:--tracepoint] (option:--all | 'NAME'[,'NAME']...)
44 [option:--loglevel='LOGLEVEL' | option:--loglevel-only='LOGLEVEL'] [option:--filter='EXPR']
45 [option:--session='SESSION'] [option:--channel='CHANNEL']
49 The `lttng enable-event` command does one of:
51 * Create one or more recording event rules.
53 * Enable one or more disabled recording event rules.
55 See the <<enable,Enable a disabled recording event rule>> section
58 See man:lttng-concepts(7) to learn more about instrumentation points,
59 events, recording event rules, and event records.
61 The recording event rule(s) to create or enable belong to:
63 With the option:--session='SESSION' option::
64 The tracing session named 'SESSION'.
66 Without the option:--session option::
67 The current tracing session (see man:lttng-concepts(7) to learn more
68 about the current tracing session).
70 With the option:--channel='CHANNEL' option::
71 The channel named 'CHANNEL'.
73 Without the option:--channel option::
74 The channel named `channel0`.
76 If there's already a channel for the selected tracing session and domain
77 which isn't named `channel0`, the `enable-event` command fails.
78 Otherwise, it automatically creates it.
80 List the recording event rules of a specific tracing session
81 and/or channel with the man:lttng-list(1) and man:lttng-status(1)
84 Disable an enabled recording event rule with the
85 man:lttng-disable-event(1) command.
88 Overview of recording event rule conditions
89 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
90 For LTTng to emit and record an event{nbsp}__E__,{nbsp}__E__ must
91 satisfy *all* the conditions of a recording event rule{nbsp}__ER__, that
95 You set the following conditions when you create or
96 enable{nbsp}__ER__ with the `enable-event` command:
99 * The instrumentation point type from which LTTng creates{nbsp}__E__
102 See the <<inst-point-type-cond,Instrumentation point type condition>>
105 * A pattern matches the name of{nbsp}__E__ while another pattern
108 See the <<event-name-cond,Event name condition>> section below.
110 * The log level of the instrumentation point from which LTTng
111 creates{nbsp}__E__ is at least as severe as some value, or is exactly
114 See the <<inst-point-log-level-cond,Instrumentation point log level condition>>
117 * The fields of the payload of{nbsp}__E__ and the current context fields
118 satisfy a filter expression.
120 See the <<filter-cond,Event payload and context filter condition>>
124 Implicit conditions::
127 * _ER_ itself is enabled.
129 A recording event rule is enabled on creation.
131 Enable a disabled recording event rule with the `enable-event` command.
133 * The channel to which{nbsp}__ER__ is attached is enabled.
135 A channel is enabled on creation.
137 Enable a disabled channel with the man:lttng-enable-channel(1) command.
139 * The tracing session of{nbsp}__ER__ is active (started).
141 A tracing session is inactive (stopped) on creation.
143 Start an inactive tracing session with the man:lttng-start(1) command.
145 * The process for which LTTng creates{nbsp}__E__ is allowed to record
148 All processes are allowed to record events on tracing session
151 Use the man:lttng-track(1) and man:lttng-untrack(1) commands to select
152 which processes are allowed to record events based on specific process
156 The dedicated command-line options of most conditions are optional: if
157 you don't specify the option, the associated condition is always
161 [[inst-point-type-cond]]
162 Instrumentation point type condition
163 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
164 An event{nbsp}__E__ satisfies the instrumentation point type condition
165 of a recording event rule if the instrumentation point from which LTTng
166 creates{nbsp}__E__ is:
168 For the Linux kernel tracing domain (option:--kernel option)::
169 With the option:--tracepoint option or without any other instrumentation point type option:::
170 An LTTng kernel tracepoint, that is, a statically defined point
171 in the source code of the kernel image or of a kernel module
172 with LTTng kernel tracer macros.
174 As of LTTng{nbsp}{lttng_version}, this is the default instrumentation
175 point type of the Linux kernel tracing domain, but this may change in
178 List the available Linux kernel tracepoints with `lttng list --kernel`.
179 See man:lttng-list(1) to learn more.
181 With the option:--syscall option:::
182 The entry and exit of a Linux kernel system call.
184 List the available Linux kernel system call instrumentation points with
185 `lttng list --kernel --syscall`. See man:lttng-list(1) to learn more.
187 With the option:--probe option:::
188 A Linux kprobe, that is, a single probe dynamically placed in
189 the compiled kernel code.
191 The argument of the option:--probe option is the location of the
192 kprobe to insert, either a symbol or a
193 memory address, while 'RECORDNAME' is the name of the record
194 of{nbsp}__E__ (see the <<er-name,Event record name>> section below).
196 The payload of a Linux kprobe event is empty.
198 With the option:--userspace-probe option:::
199 A Linux user space probe, that is, a single probe dynamically
200 placed at the entry of a compiled user space application/library
201 function through the kernel.
203 The argument of the option:--userspace-probe option is the location
204 of the user space probe to insert, one of:
207 * A path and symbol (ELF method).
208 * A path, provider name, and probe name (SystemTap User-level Statically
209 Defined Tracing (USDT) method; a DTrace-style marker).
211 As of LTTng{nbsp}{lttng_version}, LTTng only supports USDT probes which
212 are :not: reference-counted.
215 'RECORDNAME' is the name of the record of{nbsp}__E__ (see the
216 <<er-name,Event record name>> section below).
218 The payload of a Linux user space probe event is empty.
220 With the option:--function option:::
221 A Linux kretprobe, that is, two probes dynamically placed at the
222 entry and exit of a function in the compiled kernel code.
224 The argument of the option:--function option is the location of the
225 Linux kretprobe to insert, either a symbol or
226 a memory address, while 'RECORDNAME' is the name of the record
227 of{nbsp}__E__ (see the <<er-name,Event record name>> section below).
229 The payload of a Linux kretprobe event is empty.
231 For the user space tracing domain (option:--userspace option)::
232 With or without the option:--tracepoint option:::
233 An LTTng user space tracepoint, that is, a statically defined
234 point in the source code of a C/$$C++$$ application/library with
235 LTTng user space tracer macros.
237 As of LTTng{nbsp}{lttng_version}, this is the default and sole
238 instrumentation point type of the user space tracing domain, but this
239 may change in the future.
241 List the available user space tracepoints with `lttng list --userspace`.
242 See man:lttng-list(1) to learn more.
244 For the `java.util.logging` (option:--jul option), Apache log4j (option:--log4j option), and Python (option:--python option) tracing domains::
245 With or without the option:--tracepoint option:::
248 As of LTTng{nbsp}{lttng_version}, this is the default and sole
249 instrumentation point type of the `java.util.logging`, Apache log4j, and
250 Python tracing domains, but this may change in the future.
252 List the available Java and Python loggers with `lttng list --jul`,
253 `lttng list --log4j`, and `lttng list --python`. See man:lttng-list(1)
260 An event{nbsp}__E__ satisfies the event name condition of a recording
261 event rule{nbsp}__ER__ if the two following statements are true:
263 * You specify the option:--all option or, depending on the
264 instrumentation type condition (see the
265 <<inst-point-type-cond,Instrumentation point type condition>> section
266 above) of{nbsp}__ER__, 'NAME' matches:
270 The full name of the tracepoint from which LTTng creates{nbsp}__E__.
272 Note that the full name of a user space tracepoint is
273 __PROVIDER__++:++__NAME__, where __PROVIDER__ is the tracepoint provider
274 name and __NAME__ is the tracepoint name.
277 The name of the Java or Python logger from which LTTng
281 The name of the system call, without any `sys_` prefix, from which
282 LTTng creates{nbsp}__E__.
285 * You don't specify the option:--exclude=__XNAME__[++,++__XNAME__]...
286 option or, depending on the instrumentation type condition
287 of{nbsp}__ER__, none of the 'XNAME' arguments matches the full name of
288 the user space tracepoint from which LTTng creates{nbsp}__E__.
290 The option:--exclude option is only available with the option:--userspace
293 This condition is only meaningful for the LTTng tracepoint, logging
294 statement, and Linux system call instrumentation point types: it's
295 always satisfied for the other types.
297 In all cases, 'NAME' and 'XNAME' are globbing patterns: the `*`
298 character means ``match anything''. To match a literal `*` character,
299 use :escwc:. To match a literal `,` character, use
302 IMPORTANT: Make sure to **single-quote** 'NAME' and 'XNAME' when they
303 contain the `*` character and when you run the `enable-event` command
306 With the LTTng tracepoint, logging statement, and Linux system call
307 instrumentation point types, the `enable-event` command creates or
308 enables one independent recording event rule per 'NAME' argument
309 (non-option, comma-separated). With the option:--all option, the
310 `enable-event` command creates or enables a single recording event rule.
313 [[inst-point-log-level-cond]]
314 Instrumentation point log level condition
315 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
316 An event{nbsp}__E__ satisfies the instrumentation point log level
317 condition of a recording event rule if either:
319 * The option:--loglevel and option:--loglevel-only options are
322 * The log level of the LTTng user space tracepoint or logging statement
323 which creates{nbsp}__E__ is:
324 With the option:--loglevel='LOGLEVEL' option::
325 At least as severe as 'LOGLEVEL'.
327 With the option:--loglevel-only='LOGLEVEL' option::
330 This condition is only meaningful for the LTTng user space tracepoint
331 and logging statement instrumentation point types: it's always satisfied
334 The available values of 'LOGLEVEL' are, depending on the tracing domain,
335 from the most to the least severe:
337 User space (option:--userspace option)::
347 * `DEBUG_PROGRAM` (8)
348 * `DEBUG_PROCESS` (9)
349 * `DEBUG_MODULE` (10)
351 * `DEBUG_FUNCTION` (12)
355 `java.util.logging` (option:--jul option)::
357 * `OFF` (`INT32_MAX`)
365 * `ALL` (`INT32_MIN`)
367 Apache log4j (option:--log4j option)::
369 * `OFF` (`INT32_MAX`)
376 * `ALL` (`INT32_MIN`)
378 Python (option:--python option)::
389 Event payload and context filter condition
390 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
391 An event{nbsp}__E__ satisfies the event payload and context filter
392 condition of a recording event rule if the option:--filter='EXPR'
393 option is missing or if 'EXPR' is _true_.
395 This condition is only meaningful for the LTTng tracepoint and Linux
396 system call instrumentation point types: it's always satisfied for other
399 'EXPR' can contain references to the payload fields of{nbsp}__E__ and
400 to the current context fields.
402 IMPORTANT: Make sure to **single-quote** 'EXPR' when you run the
403 `enable-event` command from a shell, as filter expressions typically
404 include characters having a special meaning for most shells.
406 The expected syntax of 'EXPR' is similar to the syntax of a
407 C{nbsp}language conditional expression (an expression which an `if`
408 statement can evaluate), but there are a few differences:
410 * A _NAME_ expression identifies an event payload field named
411 _NAME_ (a C{nbsp}identifier).
413 Use the C{nbsp}language dot and square bracket notations to access
414 nested structure and array/sequence fields. You can only use a constant,
415 positive integer number within square brackets. If the index is out of
416 bounds, 'EXPR' is _false_.
418 The value of an enumeration field is an integer.
420 When a field expression doesn't exist, 'EXPR' is _false_.
422 Examples: `my_field`, `target_cpu`, `seq[7]`, `msg.user[1].data[2][17]`.
424 * A ++$ctx.++__TYPE__ expression identifies the statically-known context
425 field having the type _TYPE_ (a C{nbsp}identifier).
427 List the available statically-known context field names with the
428 man:lttng-add-context(1) command.
430 When a field expression doesn't exist, 'EXPR' is _false_.
432 Examples: `$ctx.prio`, `$ctx.preemptible`,
433 `$ctx.perf:cpu:stalled-cycles-frontend`.
435 * A ++$app.++__PROVIDER__++:++__TYPE__ expression identifies the
436 application-specific context field having the type _TYPE_ (a
437 C{nbsp}identifier) from the provider _PROVIDER_ (a C{nbsp}identifier).
439 When a field expression doesn't exist, 'EXPR' is _false_.
441 Example: `$app.server:cur_user`.
443 * Compare strings, either string fields or string literals
444 (double-quoted), with the `==` and `!=` operators.
446 When comparing to a string literal, the `*` character means ``match
447 anything''. To match a literal `*` character, use :escwc:.
449 Examples: `my_field == "user34"`, `my_field == my_other_field`,
450 `my_field == "192.168.*"`.
452 * The precedence table of the operators which are supported in 'EXPR'
453 is as follows. In this table, the highest precedence is{nbsp}1:
457 |Precedence |Operator |Description |Associativity
458 |1 |`-` |Unary minus |Right-to-left
459 |1 |`+` |Unary plus |Right-to-left
460 |1 |`!` |Logical NOT |Right-to-left
461 |1 |`~` |Bitwise NOT |Right-to-left
462 |2 |`<<` |Bitwise left shift |Left-to-right
463 |2 |`>>` |Bitwise right shift |Left-to-right
464 |3 |`&` |Bitwise AND |Left-to-right
465 |4 |`^` |Bitwise XOR |Left-to-right
466 |5 |`\|` |Bitwise OR |Left-to-right
467 |6 |`<` |Less than |Left-to-right
468 |6 |`<=` |Less than or equal to |Left-to-right
469 |6 |`>` |Greater than |Left-to-right
470 |6 |`>=` |Greater than or equal to |Left-to-right
471 |7 |`==` |Equal to |Left-to-right
472 |7 |`!=` |Not equal to |Left-to-right
473 |8 |`&&` |Logical AND |Left-to-right
474 |9 |`\|\|` |Logical OR |Left-to-right
477 Parentheses are supported to bypass the default order.
479 IMPORTANT: Unlike the C{nbsp}language, the bitwise AND and OR operators
480 (`&` and `|`) in 'EXPR' take precedence over relational operators (`<`,
481 `<=`, `>`, `>=`, `==`, and `!=`). This means the expression `2 & 2 == 2`
482 is _true_ while the equivalent C{nbsp}expression is _false_.
484 The arithmetic operators are :not: supported.
486 LTTng first casts all integer constants and fields to signed 64-bit
487 integers. The representation of negative integers is two's complement.
488 This means that, for example, the signed 8-bit integer field 0xff (-1)
489 becomes 0xffffffffffffffff (still -1) once casted.
491 Before a bitwise operator is applied, LTTng casts all its operands to
492 unsigned 64-bit integers, and then casts the result back to a signed
493 64-bit integer. For the bitwise NOT operator, it's the equivalent of
494 this C{nbsp}expression:
498 (int64_t) ~((uint64_t) val)
501 For the binary bitwise operators, it's the equivalent of those
506 (int64_t) ((uint64_t) lhs >> (uint64_t) rhs)
507 (int64_t) ((uint64_t) lhs << (uint64_t) rhs)
508 (int64_t) ((uint64_t) lhs & (uint64_t) rhs)
509 (int64_t) ((uint64_t) lhs ^ (uint64_t) rhs)
510 (int64_t) ((uint64_t) lhs | (uint64_t) rhs)
513 If the right-hand side of a bitwise shift operator (`<<` and `>>`) is
514 not in the [0,{nbsp}63] range, then 'EXPR' is _false_.
518 Use the man:lttng-track(1) and man:lttng-untrack(1) commands to allow or
519 disallow processes to record LTTng events based on their attributes
520 instead of using equivalent statically-known context fields in 'EXPR'
523 The former method is much more efficient.
528 ----------------------------
529 msg_id == 23 && size >= 2048
530 ----------------------------
532 -------------------------------------------------
533 $ctx.procname == "lttng*" && (!flag || poel < 34)
534 -------------------------------------------------
536 ---------------------------------------------------------
537 $app.my_provider:my_context == 17.34e9 || some_enum >= 14
538 ---------------------------------------------------------
540 ---------------------------------------
541 $ctx.cpu_id == 2 && filename != "*.log"
542 ---------------------------------------
544 ------------------------------------------------
545 eax_reg & 0xff7 == 0x240 && x[4] >> 12 <= 0x1234
546 ------------------------------------------------
552 When LTTng records an event{nbsp}__E__, the resulting event record has a
553 name which depends on the instrumentation point type condition (see the
554 <<inst-point-type-cond,Instrumentation point type condition>> section
555 above) of the recording event rule which matched{nbsp}__E__:
557 LTTng tracepoint (option:--kernel/option:--userspace and option:--tracepoint options)::
558 Full name of the tracepoint from which LTTng creates{nbsp}__E__.
560 Note that the full name of a user space tracepoint is
561 __PROVIDER__++:++__NAME__, where __PROVIDER__ is the tracepoint provider
562 name and __NAME__ is the tracepoint name.
564 `java.util.logging` logging statement (option:--jul and option:--tracepoint options)::
567 Such an event record has a string field `logger_name` which contains the
568 name of the `java.util.logging` logger from which LTTng
571 Apache log4j logging statement (option:--log4j and option:--tracepoint options)::
574 Such an event record has a string field `logger_name` which contains the
575 name of the Apache log4j logger from which LTTng creates{nbsp}__E__.
577 Python logging statement (option:--python and option:--tracepoint options)::
580 Such an event record has a string field `logger_name` which contains the
581 name of the Python logger from which LTTng creates{nbsp}__E__.
583 Linux system call (option:--kernel and option:--syscall options)::
585 ++syscall_entry_++__NAME__, where _NAME_ is the name of the
586 system call from which LTTng creates{nbsp}__E__, without any
590 ++syscall_exit_++__NAME__, where _NAME_ is the name of the
591 system call from which LTTng creates{nbsp}__E__, without any
594 Linux kprobe (option:--kernel and option:--probe options)::
595 Linux user space probe (option:--kernel and option:--userspace-probe options)::
596 'RECORDNAME' (first non-option argument).
598 Linux kretprobe (option:--kernel and option:--function options)::
600 __RECORDNAME__++_entry++
603 __RECORDNAME__++_exit++
607 Enable a disabled recording event rule
608 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
609 The `enable-event` command can enable a disabled recording event rule,
610 as listed in the output of the man:lttng-list(1) command.
612 You may enable a disabled recording event rule regardless of the
613 activity (started or stopped) of its tracing session (see
614 man:lttng-start(1) and man:lttng-stop(1)).
616 To enable a disabled recording event rule, run the `enable-event`
617 command with the exact same options and arguments that you used to
618 create it. In particular, with the option:--filter='EXPR' option, 'EXPR'
619 must be the exact same string as the one you used on creation.
622 include::common-lttng-cmd-options-head.txt[]
629 option:-j, option:--jul::
630 Create or enable recording event rules in the `java.util.logging`
631 (JUL) tracing domain.
633 option:-k, option:--kernel::
634 Create or enable recording event rules in the Linux kernel tracing
637 option:-l, option:--log4j::
638 Create or enable recording event rules in the Apache log4j tracing
641 option:-p, option:--python::
642 Create or enable recording event rules in the Python tracing domain.
644 option:-u, option:--userspace::
645 Create or enable recording event rules in the user space tracing
651 option:-c 'CHANNEL', option:--channel='CHANNEL'::
652 Create or enable recording event rules attached to the channel named
653 'CHANNEL' instead of `channel0`.
655 option:-s 'SESSION', option:--session='SESSION'::
656 Create or enable recording event rules in the tracing session named
657 'SESSION' instead of the current tracing session.
660 Instrumentation point type condition
661 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
662 See the <<inst-point-type-cond,Instrumentation point type condition>>
667 option:--function='LOC'::
668 Only match Linux kretprobe events.
670 Only available with the option:--kernel option.
675 * A function address (`0x` hexadecimal prefix supported).
676 * A function symbol name.
677 * A function symbol name and an offset
678 (__SYMBOL__++pass:[+]++__OFFSET__ format).
681 You must specify the event record name with 'RECORDNAME'. See the
682 <<er-name,Event record name>> section above to learn more.
684 option:--probe='LOC'::
685 Only match Linux kprobe events.
687 Only available with the option:--kernel option.
692 * An address (`0x` hexadecimal prefix supported).
694 * A symbol name and an offset (__SYMBOL__++pass:[+]++__OFFSET__ format).
697 You must specify the event record name with 'RECORDNAME'. See the
698 <<er-name,Event record name>> section above to learn more.
700 option:--userspace-probe='LOC'::
701 Only match Linux user space probe events.
703 Only available with the option:--kernel option.
708 \[++elf:++]__PATH__++:++__SYMBOL__::
709 Probe an available symbol within a user space application or
714 Application or library path.
720 * The name of an application as found in the directories listed in the
721 `PATH` environment variable.
724 Symbol name of the function of which to instrument the entry.
726 'SYMBOL' can be any defined code symbol in the output of the man:nm(1)
727 command, including with its nloption:--dynamic option, which lists
731 As of LTTng{nbsp}{lttng_version}, not specifying `elf:` is equivalent to
732 specifying it, but this default may change in the future.
736 * `--userspace-probe=/usr/lib/libc.so.6:malloc`
737 * `--userspace-probe=./myapp:createUser`
738 * `--userspace-probe=elf:httpd:ap_run_open_htaccess`
740 ++sdt:++__PATH__++:++__PROVIDER__++:++__NAME__::
741 Use a SystemTap User-level Statically Defined Tracing (USDT) probe
742 within a user space application or library.
746 Application or library path.
752 * The name of an application as found in the directories listed in the
753 `PATH` environment variable.
757 USDT provider and probe names.
759 For example, with the following USDT probe:
763 DTRACE_PROBE2("server", "accept_request",
764 request_id, ip_addr);
767 The provider/probe name pair is `server:accept_request`.
770 Example: `--userspace-probe=sdt:./build/server:server:accept_request`
773 You must specify the event record name with 'RECORDNAME'. See the
774 <<er-name,Event record name>> section above to learn more.
777 Only match Linux system call events.
779 Only available with the option:--kernel option.
781 option:--tracepoint::
784 With the option:--kernel or option:--userspace option:::
785 LTTng tracepoint events.
786 With the option:--jul, option:--log4j, or option:--python option:::
789 With the option:--kernel, not specifying any of the instrumentation
790 point type options is equivalent to specifying the option:--tracepoint
791 option, but this default may change in the future.
793 With the option:--userspace, option:--jul, option:--log4j, and
794 option:--python options, not specifying the option:--tracepoint option
795 is equivalent to specifying it, but this default may change in the
801 See the <<event-name-cond,Event name condition>> section above.
803 option:-a, option:--all::
804 Equivalent to a single 'NAME' argument (LTTng tracepoint or logger
805 name) set to `*` (match anything).
807 You may :not: use this option with a 'NAME' argument.
809 option:-x 'XNAME'[,'XNAME']..., option:--exclude='XNAME'[,'XNAME']...::
810 Only match events of which none of the 'XNAME' arguments
811 matches the full name of the LTTng user space tracepoint.
813 Only available with the option:--userspace option.
815 'XNAME' is a globbing pattern: the `*` character means ``match
816 anything''. To match a literal `*` character, use :escwc:. To match
817 a literal `,` character, use :esccomma:.
820 Instrumentation point log level condition
821 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
822 See the <<inst-point-log-level-cond,Instrumentation point log level
823 condition>> section above.
827 option:--loglevel='LOGLEVEL'::
828 Only match events of which the log level of the LTTng tracepoint or
829 logging statement is at least as severe as 'LOGLEVEL'.
831 option:--loglevel-only='LOGLEVEL'::
832 Only match events of which the log level of the LTTng tracepoint or
833 logging statement is exactly 'LOGLEVEL'.
835 The instrumentation point log level options above are :not: available
836 with the option:--kernel option.
839 Event payload and context filter condition
840 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
841 See the <<filter-cond,Event payload and context filter condition>>
844 option:-f 'EXPR', option:--filter='EXPR'::
845 Only match events of which 'EXPR', which can contain references to
846 event payload and current context fields, is _true_.
848 This option is only available with the option:--tracepoint or
849 option:--syscall option.
852 include::common-lttng-cmd-help-options.txt[]
855 include::common-lttng-cmd-after-options.txt[]
858 include::common-footer.txt[]
864 man:lttng-disable-event(1),
865 man:lttng-enable-channel(1),
869 man:lttng-concepts(7)