About ‘Regex’ in Redirections

Part-by-Part Explanation

Source URL: ^/([0-9]{4})/([0-9]{2})/([0-9]{2})/(.*)

① ^/ “URL must start with /”

• ^ → Beginning of URL
• / → Immediately followed by a slash

② ([0-9]{4}) = Year (YYYY) → Captured in $1

• [0-9] → Digits 0-9
• {4} → 4 digits
• () → Capture group

③ /([0-9]{2}) = Month (MM) → Captured in $2

• {2} → Two-digit number

④ /([0-9]{2}) = Day (DD) → Captured in $3

⑤ /(.*) = Slug portion (super important)

• . → Any single character
• * → Zero or more characters
• (.*) → Captures everything together

Capture Correspondence

Group	Content
$1	Year (YYYY)
$2	Month (MM)
$3	Day (DD)
$4	Slug (Article Title)

Target URL: /$4
Meaning

• Discard the year, month, and day ($1 $2 $3) entirely
• Keep only the slug portion
• $4 includes the trailing /, so it’s not needed here

Actual Conversion Example

• Before: “Date and Post Name” https://taracotapas.com/2026/01/20/sample-post/
• After: “Post Name” https://taracotapas.com/sample-post/

2. Basics of Redirection “Regex”

Basic Parts

• (.*) ← Captures everything
• ([0-9]+) ← Numbers
• ^ / $ ← Start/End

Redirection Operation Rules

• Regex ON
• Ignore Slash / Ignore Case are OFF by default
• Source / Target are relative paths
• Use 301 (permanent) redirects
• Order rules from broadest to narrowest

3. Commonly Used “Regex” Examples

① URL with year/month/day → Slug only

• Purpose: WordPress permalink change (/%year%/%month%/%day%/ → /%postname%/)
• Source: ^/([0-9]{4})/([0-9]{2})/([0-9]{2})/(.*)
• Target: /$4

② Move an entire directory structure to a different location

• Purpose: /old-blog/xxx → /blog/xxx
• Source: ^/old-blog/(.*)
• Target: /blog/$1

③ Japanese URL → English slug (with sequential number)

• Purpose: Organize Japanese/English URLs
• Source: ^/ja/Japanese-title-([0-9]+)
• Target: /ja/english-title-$1

④ Remove index.php / index.html

• Purpose: SEO normalization / rescue old URLs
• Source: ^/(.*)/index\.(php|html?)$
• Target: /$1/

⑤ Remove trailing slash → Add trailing slash

• Purpose: URL standardization (prevent SEO issues)
• Source: ^(.+[^/])$
• Target: $1/

⑥ http → https

• Purpose: Redirecting traffic after SSL migration
• Source: ^http://(.*)
• Target: https://$1

⑦ Upper-case URL → Lower-case URL

• Purpose: When external incoming URLs are messy
• Source: ^/(.*[A-Z].*)
• Target: /$1

⑧ Redirect while ignoring query URLs

• Purpose: Ignore ?utm_source=xxx
• Source: ^/some-page/?$
• Target: /some-page/

⑨ Bulk rescue for URLs generating massive 404s

• Purpose: Search Console compliance
• Source: ^/tag/(.*)
• Target: /blog/

⑩ Catch both ja and en (multilingual)

• Purpose: When using Polylang / WPML
• Source: ^/(ja|en)/(.*)
• Target: /$1/new-path/$2