404 regular-expression advice needed

It seems you can have both post ID’s and numbers in the page slug. So my-post-2 could be my-post with post ID 2 or my-post-2 with no post ID. In theory there is no way to solve this, but in practice maybe we can assume that you won’t have ten similar slugs, so the slug number is at most one digit, and the post ID is at least two digits. This way you can add the few posts with IDs 1-9 with a complete non-regex redirect.

This regex should match anything of the form /[year]/[month]/[optional-day]/[post-slug-with-optional single digit]-[optional post id][optional /]:

^/(\d{4})/\d{2}/(\d{2}/)?([^/]+?)(-\d{2,})?/?$

^/                                              Start of the string, one slash
  (\d{4})                                       Four digits, saved for later
         /                                      One slash
          \d{2}                                 Two digits, not saved
               /                                One slash
                (\d{2}/)?                       Two digits and a slash, optional
                         ([^/]+?)               Everything that is not a slash, but not greedy
                                 (-\d{2,})?     A dash and two or more digits, optional
                                           /?$  Optional slash and end of the string

The year is in the first captured group, the post slug in the third.

The “not greedy” is important because it makes sure that part of the regex doesn’t “eat up” the post-ID part that is matched after it. It is created by appending the ? to the +. I believe this does not work under Apache 1.3, so WordPress strips it out before it creates the mod_rewrite rules. So if it does not work when you put it in the Apache part of Redirection, try it in the WordPress part.

Related Posts:

  1. How to set up redirects for category paginated pages after adding /category/ to permalink
  2. Using or ‘|’ in regex [duplicate]
  3. What is a Context Free Grammar?
  4. What does \’.- mean in a Regular Expression
  5. How can I exclude one word with grep?
  6. How can I validate an email address using a regular expression?
  7. Regular expression to match a line that doesn’t contain a word
  8. Difference between \b and \B in regex
  9. Regex: ignore case sensitivity
  10. What does the regex \S mean in JavaScript?
  11. How can I validate an email address using a regular expression?
  12. Regex: ignore case sensitivity
  13. Python regex AttributeError: ‘NoneType’ object has no attribute ‘group’
  14. Regular Expression for alphanumeric and underscores
  15. What is the difference between the regular expressions [^\d\s] and [\D\S]
  16. Regular Expression for alphanumeric and underscores
  17. grep –ignore-case –only
  18. Regex AND operator
  19. python re.split() to split by spaces, commas, and periods, but not in cases like 1,000 or 1.50
  20. python re.split() to split by spaces, commas, and periods, but not in cases like 1,000 or 1.50
  21. Regex to test if string begins with http:// or https://
  22. Regular Expression to match string starting with a specific word
  23. Regular Expressions: Is there an AND operator?
  24. Regular expression to match standard 10 digit phone number
  25. What is a non-capturing group in regular expressions?
  26. Split string on whitespace in Python
  27. How to validate an email address in PHP
  28. What is a non-capturing group in regular expressions?
  29. Regular expression to match standard 10 digit phone number
  30. How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops
  31. Python string.replace regular expression
  32. How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops
  33. Symbol for any number of any characters in regex?
  34. Grep and Python
  35. Regex – Does not contain certain Characters
  36. Regex how to match an optional character
  37. How to validate an email address in JavaScript
  38. Using Bash regex match (=~) where regex includes quotes (” characters)
  39. Regular expression to match a word or its prefix
  40. How can I remove punctuation from input text in Java?
  41. Regular expression for exact match of a string
  42. Using the star sign in grep
  43. Regex for string contains?
  44. Question marks in regular expressions
  45. Difference between \w and \b regular expression meta characters
  46. Regular Expression – Validate Gmail addresses
  47. How can I remove punctuation from input text in Java?
  48. How can I output only captured groups with sed?
  49. How to negate specific word in regex?
  50. What is the grep equivalent in Python?
  51. javascript HTML from document.body.innerHTML
  52. Which regular expression operator means ‘Don’t’ match this character?
  53. Python re.split() vs split()
  54. Regex Explanation ^.*$ [duplicate]
  55. Negative matching using grep (match lines that do not contain foo)
  56. How to replace a whole line with sed?
  57. Regex match everything after question mark?
  58. How to validate phone number using PHP?
  59. Can a URL contain a semicolon and still be valid?
  60. How is \\n and \\\n interpreted by the expanded regular expression?
  61. Regular Expression to reformat a US phone number in Javascript
  62. Regex to match only letters
  63. Finding the complement of a DFA?
  64. RegEx to find two or more consecutive chars
  65. RE error: illegal byte sequence on Mac OS X
  66. Regex to match an optional ‘+’ symbol followed by any number of digits
  67. Regular expressions in C: examples?
  68. How to ignore whitespace in a regular expression subject string?
  69. Regular expression for a string that does not start with a sequence
  70. Regex: matching up to the first occurrence of a character
  71. Regex credit card number tests
  72. Regular expression – starting and ending with a character string
  73. /bb|[^b]{2}/ how does it work?
  74. How do I match any character across multiple lines in a regular expression?
  75. Regular expression to remove HTML tags from a string
  76. Regex that matches integers in between whitespace or start/end of string only
  77. Regular Expressions- Match Anything
  78. What is the difference between square brackets and parentheses in a regex?
  79. My Vim replace with a regex is throwing a `E488: Trailing characters`
  80. How to replace a string in an existing file in Perl
  81. Regex empty string or email
  82. Regex to validate date formats dd/mm/YYYY, dd-mm-YYYY, dd.mm.YYYY, dd mmm YYYY, dd-mmm-YYYY, dd/mmm/YYYY, dd.mmm.YYYY with Leap Year Support
  83. Regex difference: (\w+)? and (\w*)
  84. extract shortcodes from string
  85. How to remove “YEAR/MONTH/” from uploads URL & redirect old URL to the new form?
  86. preg_replace and comment_form_defaults
  87. htaccess redirect – replace special character
  88. How to use a variable as a className inside preg_match_all parameters?
  89. Regex expression for redirecting image URLs to another folder
  90. Adding span tags to post titles using regex
  91. Redirect regex misbehaving when placeholder empty
  92. Redirect non www to www using redirection plugin regex
  93. Remove Custom HTML Posts Using Regex
  94. Regexes allow only [a-z][A-Z][0-9] and –
  95. Redirect after Permalink change – What regex do I use?
  96. Call Shortcode Attribute Value within another function
  97. Regex For Extracting First 4 letters of search term
  98. Multisite image URLs incorrect in editor
  99. Regex for pdf’s – Old .asp Site folder structure to new WordPress Media Folder(s)
  100. Use Regex Redirection via htsaccess for RSS Feeds WordPress