How to use regular expressions

A number of apps provide advanced features that require the use of regular expressions for pattern matching. Generally, just a simple understanding of regular expressions and a few examples are enough to get by for most use cases. This page has a few simple examples to get started. Use the references for more advanced information. It is recommended to test your regular expressions in one of the well-known regex testing sites such as RegexPlanet or Regex101.

1 Simple examples 2 Advanced examples 3 References

1 Simple examples 2 Advanced examples 3 References

Regex for workflow conditions

For Jira workflow functions using regex expressions to condition whether the post function should continue processing, a blank pattern means that condition processing is not done and processing should continue.

Key tips

Dot or period (.) is a special regex character. If you really want to match on it, you need to escape it with a backslash: \.
Don't be confused with generic pattern matching used for file systems for instance. On a file system, *.png means all files ending with .png. That is an illegal regex expression. For regex you need: .*\.png, or to simplify: .*png which finds all files ending in png (not necessarily ending in an extension of PNG).
Regex is case sensitive by default. In most cases, use the case insensitive flag: (?i). See one of the examples below.
Use the Dotall mode to match across line breaks.

Simple examples

Value	Regex	Matches	Demonstrates

Value	Regex	Demonstrates
`ABC`	`A.C`	. matches any single character
`ABC`	`A.*`	indicates 0 or more characters
`ABC`	`.*C`
`A.B`	`A\.B`	Escape special regex characters with backslash if necessary
`ABC`	`AB*`	Regex is NOT generic matching
`ABC`	`A.+`	+ indicates 1 or more
`ABC`	`ABC.+`
`ABC`	`ABC.*`
`ABCD`	`ABC.*`
`ABC`	`[ABCD]`	[ ] indicates a class of characters
`ABC`	`[ABZ]`
`ABC8`	`[A-Z0-9]`	indicates a range of characters
`ABC`	`[AB^C]`	^ in a class means NOT the following character
`ABC`	`DEF\|ABC`	\| indicates OR
`image.png`	`.png\|.jpg`
`image.jpg`	`.png\|.jpg`
`image.JPG`	`.png\|.jpg`	defaults to case sensitive matching
`image.JPG`	`(?i).png\|.jpg`	(?i) indicates case insensitive matching
`ABAB`	`(AB)+`	() indicates a grouping
`ABCD`	`(AB)+`
`112233`	`\d+`	\d for digits
`A B`	`A\s*B`	\s for whitespace
`ABC`	`\S*`	\S for non whitespace
	`\S+`	Value must have at least 1 non whitespace character
`A`	`\S+`
`XYZ,ABC,UVW`	`.\bABC\b.`	Word boundaries. Finding words in a comma or blank separated list using word boundaries
`XYZ,ABCD,UVW`	`.\bABC\b.`
`ABC`	`(?m)(^ABC$)\|(^ABC,)\|(,ABC,)\|(,ABC$)`	Looking for text matches in a comma separated list by covering all cases: only, start, middle, and end. This uses the multi-line flag: (?m)
`XYZ,ABC,UVW`	`(?m)(^ABC$)\|(^ABC,)\|(,ABC,)\|(,ABC$)`
`XYZ,ABC DEF,UVW`	`(?m)(^ABC$)\|(^ABC,)\|(,ABC,)\|(,ABC$)`

Advanced examples

Value	Regex	Matches	Find	Demonstrates

Value	Regex	Demonstrates
`example.txt`	`^((?!\.png).)*$`	Find string not containing a word. In this example, files that do not have a .png extension
`example.png`	`^((?!\.png).)*$`	Find string not containing a word. In this example, files that do not have a .png extension
`example.jpeg`	`(?=^((?!\.png).)$)(?=^((?!\.jpeg).)$)`	Find string not containing a word. In this example, files that do not have a .png or .jpeg extension
`collateral wholesale retail`	`.(?=.\bretail\b.)(?=.\bcollateral\b.).`	Match exact words anywhere in string. In this case, a blank separated list of labels and both collateral and retail must be included for the match to be successful
`wholesale retail`	`.(?=.\bretail\b.)(?=.\bcollateral\b.).`	Both are required for a match
`merger acquisition`	`.\b(?:merger\|acquisition)\b.`	Match string containing either word

Content with regex label

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How to implement regex pattern for attachments that exclude either of two labels using Advanced Tables for Confluence (One Appfire Support Knowledge Base)
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How to condition the creation of issues (One Appfire Support Knowledge Base)
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How to condition issue creation (One Appfire Support Knowledge Base)
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How to add condition to a blank or empty field (One Appfire Support Knowledge Base)
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Use regex to remove Include macro from space(s) using Confluence CLI (One Appfire Support Knowledge Base)
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How to remove specific word(s) on a page using the Confluence CLI findReplaceRegex parameter (One Appfire Support Knowledge Base)
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How to add regular expression check validator for IP address and host name (One Appfire Support Knowledge Base)
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How to validate input values in the text field that are separated by comma with regular expression (One Appfire Support Knowledge Base)
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How to assign issue automatically based on Email Keywords (One Appfire Support Knowledge Base)
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Define condition based issue creation (Create on Transition for Jira)
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Add condition to a blank or an empty field (Create on Transition for Jira)
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Define condition based issue creation - Cloud (Create on Transition for Jira)
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matchStart (Power Scripts for Jira Cloud) — Returns the position where the match starts or -1 if it doesn't match.
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matchReplace (Power Scripts for Jira Cloud) — Uses a regex expression to find and replace text within a string.
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matchEnd (Power Scripts for Jira Cloud) — Returns the position where the match ends or -1 if it doesn't match.

References

RegexOne - interactive tutorials to learn how to construct regular expressions
Regexlib.com - searchable collection of user-contributed regular expressions
RegexPlanet test site - test your expressions quickly
Regex101 test site - understand a regex expression and test it
Wikipedia regular expressions
Regular expression reference
Quick reference - best once you have the concepts
Using word boundaries
Regular expression to match string not containing a word?