2.7.1.1.11. Regular Expressions

In directives .htaccess you can use perl-like regular expressions for flexible customization of rules. Regular expressions are usually used in conjunction with variables web server. Regular expression example:

RedirectMatch /([^/]*)/([^/]*)/script.php$ http://example.com/index.php?$1=$2

• . — replaces any one character.
• ? — indicates the optional use of the previous character (for example, in the construction tes?t will fit like words test so and tet).
• * — means that the previous character (group of characters) maybe repeat (this symbol indicates an optional repetition, that is, the symbol can occur either 0 times or an infinite number).
• [abc] — indicates a list of characters that match letters a, b or with.
  • [^abc] — a list of symbols that are not used. That is, any character will do except a, b or with.
  • [abc]* — a list of consecutive characters that will be found in the string.
  • [^abc]* — a list of unacceptable consecutive characters in a string.
• + — means that the previous character (group of characters) should repeat (as opposed to *, this symbol indicates a mandatory repetition, that is, the symbol can occur at least 1 time).
• ! — the logical NOT symbol, used to form exclusion rules.
• | — logical OR symbol, set in groups.
• () — grouping of structures.
• {x} — repeating a character several times, where X — the number of repetitions (several options must be set separated by commas).
• \ — escaping of service characters for their use in templates.
• .* — specifying any number of characters in any order. /.*/ — in this case, all substrings between slashes will match.

• ^ — the beginning of a line, used at the beginning of an expression.
• $ — end of line, indicated at the end of the line.

• \w — indicates a letter, number, or underscore _.
• \W — any character other than letters, numbers and underscore.
• \d — indicates any digit.
• \D — indicates any character other than numbers.
• \s — any space character (indentation).
• \S — any non—whitespace character.

Sample from ASCII table:

• [0-9] — a range of numbers from 0 to 9.
• [a-z] — a range of letters from a to z, lowercase Latin characters.
• [A-Z] — a range of letters from A to Z in uppercase.
• [a-zA-Z] or [a-Z] — a range of letters from a to Z in any case.

Lexical comparison is a comparison of characters in the order in which they are specified (in lexicographical order), which means that 12 less than 2.

• < — Lexically less.
• > — Lexically more.
• <= — Lexically less than or equal to.
• >= — Lexically greater than or equal to.
• = — Lexically equal.
• != — Lexically not the same.

Numerical comparison:

• -lt — Less.
• -gt — More.
• -le — Less or equal.
• -ge — More or equal.
• -eq — Equals.
• -ne — Not equal.

Target Path Information:

• -d — Whether the target path is a directory.
• -f — Whether the target path is a file.
• -s — Whether the target path is a file with a size greater than 0.
• -l — Whether the target path is a symbolic link.
• -x — Whether the target path has execution rights.

For example, two URLs:

1. http://example.com/someurl/44/test/regular/expression.php
2. http://example.com/url/4/another/test/somefile.php

To create a redirect template that will include all requests that start with someurl, you need to specify it like this:

RewriteCond %{REQUEST_URI} ^/someurl/

In this case, both addresses will fall under the rule:

RewriteCond %{REQUEST_URI} ^/.*url/

Using the OR value, you can achieve rules for several options:

RewriteCond %{REQUEST_URI} ^/(someurl|url)/

Using range and repetition, you can achieve rules for enumerating suitable values, the example will print the first address:

RewriteCond %{REQUEST_URI} ^(/+)[0-9]{2}(/+) 

An example like this will print the second address:

RewriteCond %{REQUEST_URI} ^(/+)[0-9](/+) 

To exclude a link from the request using regular, you should use the following rule:

RewriteCond %{REQUEST_URI} !/regular/