RegEx for Redirect Rules and SSL
At times you may need to match several various URLs based on a set of rules. If you need to create 301 redirect rules or specify pages to apply your SSL, for example. To efficiently define a group URLs you’ll will need some knowledge of RegEx.
About RegEx
A “Regular Expression”, or RegEx, is a set of characters that create a search pattern. It’s useful for redirect and SSL rules because it allows us to dynamically match any number of URLs without creating a rule for each and even without knowing what those URLs might all be.
RegEx Basics
The RegEx basic characters and phrases are useful to have an understanding of because you may need to modify our default examples later on in this article.
Character |
Interpretation |
| ^ | Match only if the characters following are at the beginning |
| $ | Match only if the characters before are at the end |
| ? | The character just before this is optional |
| (?i) | All following characters are case-insensitive |
| . | Any 1 character |
| * | Match the previous character 0 or more times |
| + | Match the previous 1 or more times |
| (x) | Capture group. The characters inside are called by a variable later. Variables are numerical such as $1 |
| .* | A wildcard; any letter, word or phrase |
| .+ | Similar to a wildcard but requires at least 1 character be present to continue |
| (?!) | Negative lookahead, the following characters are excluded |
| \ | Escape reserved character so it functions as alphanumeric instead, goes just before each reserved character |
Special & Reserved Characters
Any RegEx functional character is not assumed to be read as alphanumeric, but rather as its function in RegEx. For example, this is relevant when trying to redirect static assets which would include a period before the file extension. That period must be escaped with a backslash just before the period to say “read the next character as alphanumeric instead of as RegEx”.
| Alphanumeric | RegEx |
|---|---|
| image.png | image\.png |
The space character must be escaped with a backslash proceeding the space character as well.
| Alphanumeric | RegEx |
|---|---|
| some phrase | some\ phrase |
RegEx for Redirects
Information on adding redirects to your User Portal can be found here.
Primary Fields
- Source — Your RegEx will go here
- Destination — Full destination URL including HTTP or HTTPS
- Advanced settings > Match args — (Optional) Argument and value to append to the destination
WP Engine Redirect Rule Conditions
- Redirects should be added in the User Portal or with a plugin.
- The User Portal redirects will be faster and work more consistently.
- Redirects through a plugin are subject to caching.
- Redirects set in the User Portal can be used for static assets, such as png and html files.
- The .htaccess file has been deprecated and redirects placed there will not work.
- Redirects are read top to bottom.
- More specific rules should be added first.
- Rules are case-sensitive.
- Case-insensitive RegEx may be necessary.
- Argument values cannot include RegEx.
- ASP and ASPX pages can only be redirected from the User Portal.
- Attempting to redirect these pages with a plugin or the .htaccess will not work on WP Engine.
Redirect Examples
| Interpretation | Source RegEx | Destination |
|---|---|---|
| Redirect from one path to another path. | ^/page1/?$ | https://example.com/page2/ |
| Redirect only part of a path. | ^/old/page/?$ | https://example.com/new/page/ |
| Redirect to a new starting path, while carrying over anything that follows. Matches root page request as well as any following arguments. | ^/old/(.*) | https://example.com/new/$1 |
| Redirect to a new starting path, while carrying over anything that follows. Requires a following argument. | ^/old/(.+) | https://example.com/new/$1 |
| Capture and reuse multiple pieces of the previous path in new destination. | ^/old/(.+)/diff/(.+) | https://example.com/new/$1/other/$2 |
| Redirect a static asset, such as a PDF file. | ^/old/page\.pdf | https://example.com/new/page.pdf |
| Redirect all pages to a subdirectory, and append the page to the URL using a capture group | ^/(.*)?$ | https://example.com/somedirectory/$1 |
Case-Insensitive Redirects
Most URLs by default are lowercase. Case-insensitive redirects allow you to redirect a URL that you know may be requested with some letters in the upper or lower cases.
If redirecting to the lowercase version of the phrase a $ at the end of the source with no trailing slash, and a trailing slash on the end of the destination should prevent a redirect loop.
| Interpretation | Source RegEx | Destination |
|---|---|---|
| Upper/lower case to new | ^(?i)/post$ | https://example.com/newpost/ |
| Upper/lower case to lower case | ^(?i)/post$ | https://example.com/post/? |
Redirects with Query Args
An “arg” is the same a URL query. In a URL you can spot the Arg or Query by a question mark ?.
As a ? is a reserved RegEx character this means args need to be redirected a certain way.
- It is assumed that ? is already present when placing the value information in the Advanced Settings > Match Args field. Do not add a ? in the Match Args field to denote an arg is present.
- The Match Args field does not support RegEx.
- This means no wildcard arg redirects. You will need to use a more broad wildcard that does not require the use of an arg.
- The query and value are automatically appended as-is to the destination or excluded from the destination completely.
- Appending a ? to the end of the destination prevents the query and value from being appended to the destination.
| Interpretation | Source RegEx | Match Args | Destination |
|---|---|---|---|
| Keep the arg appended | ^/old-page | arg=something | https://example.com/new-page/ |
| Do not preserve the arg | ^/old-page | arg=something | https://example.com/new-page/? |
Negative Lookahead
A negative lookahead allows you to include anything except the denoted value.
| Source RegEx | Interpretation |
|---|---|
| ^/(?!(page)/?$) | Match all URLs, except for those ending with the specified phrase |
| ^/(?!(page1|page2|page3)/?$) | Match all URLs except for those ending with multiple specified phrase |
| ^(?<!woff2)$ | Match all URLs except for those ending with woff2 |
| ^/(?!blog(/|$)) | Match all URLs except for ones starting with /blog |
| ^((?!some-phrase).)*$ | Match all URLs except for those containing “some-phrase” |
SSL Redirects
If you do not wish to force your SSL to “Secure All URLs” then you will likely need to specify certain URLs to secure instead. In order to configure your site to use the SSL correctly in this case, you will need to configure URL paths with regex.
| Interpretation | Source RegEx |
|---|---|
| Secure a directory, but nothing below it | ^/shop/?$ |
| Secure all directories below “shop” | ^/shop/.* |
| Secure a single file | ^/shop.php |
| Secure any file of a specific type | ^/shop/.*.php |
| Secure anything that contains the phrase “shop” | ^/.*shop |
| Match “shop” anywhere in the URL regardless of upper or lower case | ^/(?i)shop |
RegEx Tools and Resources
NEXT STEP: How to add or import redirect rules
