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11. Expressões regulares

Visão geral

O padrão POSIX estendido é suportado no Zabbix.

Existem duas formas de utilizar expressões regulares no Zabbix:

  • informar uma expressão regular manualmente nos locais suportados
  • definir uma expressão regular global

Expressões regulares globais

Aqui temos um editor avançado para criar e testar expressões regulares complexas na interface web do Zabbix.

Uma vez que uma expressão regular seja criada desta forma, ela poderá ser utilizada em vários locais a referindo por seu nome precedido pelo caractere '@', por exemplo, @mycustomregexp.

Para criar uma expressão regular global:

  • Acesse Administração → Geral
  • Selecione Expressões regulares na caixa de seleção situada na barra de título
  • Clique no botão Nova expressão regular

A aba Expressões permite que você defina o nome da expressão e adicione as sub-expressões.

Parâmetro Descrição
Nome Nome da expressão regular. Qualquer caractere unicode será aceito.
Expressão Clique no link Adicionar no bloco de expressões para adicionar uma nova sub-expressão.

A partir do Zabbix 2.4.0 uma barra '/' na expressão será tratada de forma literal, sem precisar de caractere de escape. Desta forma conseguimos aproveitar expressões que contenham este caractere, da forma anterior produziria um erro.

Um nome customizado de expressão regular pode conter espaços, vírgulas, etc. Nos casos em que estes caracteres puderem causar erros de interpretação (por exemplo uma vírgula em um parâmetro de uma chave) toda a referência deverá ser colocada entre aspas duplas: ”@My custom regexp for purpose1, purpose2”.
Os nomes de expressões regulares não poderão ter as aspas duplas em outros locais (por exemplo uma regra de LLD).

Uma expressão regular pode conter várias sub-expressões, e podem ser testadas a partir da aba Testar, ao prover um texto a ser testado.

Os resultados mostrarão o status de cada sub-expressão e o resultado final do status da expressão.

Global regular expressions

There is an advanced editor for creating and testing complex regular expressions in Zabbix frontend.

Once a regular expression has been created this way, it can be used in several places in the frontend by referring to its name, prefixed with @, for example, @mycustomregexp.

To create a global regular expression:

  • Go to: Administration → General
  • Select Regular expressions from the dropdown
  • Click on New regular expression

The Expressions tab allows to set the regular expression name and add subexpressions.

All mandatory input fields are marked with a red asterisk.

Parameter Description
Name Set the regular expression name. Any Unicode characters are allowed.
Expressions Click on Add in the Expressions block to add a new subexpression.
Expression type Select expression type:
Character string included - match the substring
Any character string included - match any substring from a delimited list. The delimited list includes a comma (,), a dot (.) or a forward slash (/).
Character string not included - match any string except the substring
Result is TRUE - match the regular expression
Result is FALSE - do not match the regular expression
Expression Enter substring/regular expression.
Delimiter A comma (,), a dot (.) or a forward slash (/) to separate text strings in a regular expression. This parameter is active only when "Any character string included" expression type is selected.
Case sensitive A checkbox to specify whether a regular expression is sensitive to capitalization of letters.

A forward slash (/) in the expression is treated literally, rather than a delimiter. This way it is possible to save expressions containing a slash, without errors.

A custom regular expression name in Zabbix may contain commas, spaces, etc. In those cases where that may lead to misinterpretation when referencing (for example, a comma in the parameter of an item key) the whole reference may be put in quotes like this: "@My custom regexp for purpose1, purpose2".
Regular expression names must not be quoted in other locations (for example, in LLD rule properties).

In the Test tab the regular expression and its subexpressions can be tested by providing a test string.

Results show the status of each subexpression and total custom expression status.

Total custom expression status is defined as Combined result. If several sub expressions are defined Zabbix uses AND logical operator to calculate Combined result. It means that if at least one Result is False Combined result has also False status.

Default global regular expressions

Zabbix comes with several global regular expression in its default dataset.

Name Expression Matches
File systems for discovery ^(btrfs\|ext2\|ext3\|ext4\|jfs\|reiser\|xfs\|ffs\|ufs\|jfs\|jfs2\|vxfs\|hfs\|refs\|apfs\|ntfs\|fat32\|zfs)$ "btrfs" or "ext2" or "ext3" or "ext4" or "jfs" or "reiser" or "xfs" or "ffs" or "ufs" or "jfs" or "jfs2" or "vxfs" or "hfs" or "refs" or "apfs" or "ntfs" or "fat32" or "zfs"
Network interfaces for discovery ^Software Loopback Interface Strings starting with "Software Loopback Interface".
^lo$ "lo"
^(In)?[Ll]oop[Bb]ack[0-9._]*$ Strings that optionally start with "In", then have "L" or "l", then "oop", then "B" or "b", then "ack", which can be optionally followed by any number of digits, dots or underscores.
^NULL[0-9.]*$ Strings starting with "NULL" optionally followed by any number of digits or dots.
^[Ll]o[0-9.]*$ Strings starting with "Lo" or "lo" and optionally followed by any number of digits or dots.
^[Ss]ystem$ "System" or "system"
^Nu[0-9.]*$ Strings starting with "Nu" optionally followed by any number of digits or dots.
Storage devices for SNMP discovery ^(Physical memory\|Virtual memory\|Memory buffers\|Cached memory\|Swap space)$ "Physical memory" or "Virtual memory" or "Memory buffers" or "Cached memory" or "Swap space"
Windows service names for discovery ^(MMCSS\|gupdate\|SysmonLog\|clr_optimization_v2.0.50727_32\|clr_optimization_v4.0.30319_32)$ "MMCSS" or "gupdate" or "SysmonLog" or strings like "clr_optimization_v2.0.50727_32" and "clr_optimization_v4.0.30319_32" where instead of dots you can put any character except newline.
Windows service startup states for discovery ^(automatic\|automatic delayed)$ "automatic" or "automatic delayed"

Examples

Example 1

Use of the following expression in low-level discovery to discover databases except a database with a specific name:

^TESTDATABASE$

regexp_expr_2.png

Chosen Expression type: "Result is FALSE". Doesn't match name, containing string "TESTDATABASE".

Example with an inline regex modifier

Use of the following regular expression including an inline modifier (?i) to match the characters "error":

(?i)error

regexp_expr_3a.png

Chosen Expression type: "Result is TRUE". Characters "error" are matched.

Another example with an inline regex modifier

Use of the following regular expression including multiple inline modifiers to match the characters after a specific line:

(?<=match (?i)everything(?-i) after this line\n)(?sx).*# we add s modifier to allow . match newline characters

regexp_expr_4_new.png

Chosen Expression type: "Result is TRUE". Characters after a specific line are matched.

g modifier can't be specified in line. The list of available modifiers can be found in pcresyntax man page. For more information about PCRE syntax please refer to PCRE HTML documentation.

Regular expression support by location

Location Regular expression Global regular expression Comments
Agent items
eventlog[] Yes Yes regexp, severity, source, eventid parameters
log[] regexp parameter
log.count[]
logrt[] Yes/No regexp parameter supports both, file_regexp parameter supports non-global expressions only
logrt.count[]
proc.cpu.util[] No cmdline parameter
proc.mem[]
proc.num[]
sensor[] device and sensor parameters on Linux 2.4
system.hw.macaddr[] interface parameter
system.sw.packages[] package parameter
vfs.dir.count[] regex_incl, regex_excl, regex_excl_dir parameters
vfs.dir.size[] regex_incl, regex_excl, regex_excl_dir parameters
vfs.file.regexp[] regexp parameter
vfs.file.regmatch[]
web.page.regexp[]
SNMP traps
snmptrap[] Yes Yes regexp parameter
Item value preprocessing Yes No pattern parameter
Functions for triggers/calculated items
count() Yes Yes pattern parameter if operator parameter is regexp or iregexp
countunique() Yes Yes
find() Yes Yes
logeventid() Yes Yes pattern parameter
logsource()
Low-level discovery
Filters Yes Yes Regular expression field
Overrides Yes No In matches, does not match options for Operation conditions
Action conditions Yes No In matches, does not match options for Host name and Host metadata autoregistration conditions
Web monitoring Yes No Variables with a regex: prefix
Required string field
User macro context Yes No In macro context with a regex: prefix
Macro functions
regsub() Yes No pattern parameter
iregsub()
Icon mapping Yes Yes Expression field
Value mapping Yes No Value field if mapping type is regexp