Introduction
This article is an extract from the 2 hours long video in here.
To use mod-rewrite, the regular expression has to be covered briefly first.
Regular Expression
Regular Express is use to parase character by character.
Online tool: regexr.com
Regular Expression – Meta Characters
| Common Meta characters | Meaning | |
|---|---|---|
| ^ | start of the pattern, begins with the following character. | |
| $ | end of the pattern, ends with the preceding character. | |
| . | dot | matches any characters |
| \ | backslash | escape the following character so it become the literal character. |
| ? | quantity meta | preceding char has zero or 1 occurance |
| * | quantity meta asterisk | preceding char has zero or more occurances |
| + | quantity meta | preceding char has 1 or more occurances |
| .+ | one or more occurances of any character | |
| ( ) | grouping | grouping which can be put into a variable, e.g. $1 |
| (com|net|org) | either one in the grouping can match | |
| [a-z] [0-9] [A-Z] | character class | –> any one lower case character can match –> any digit can match –> any one uppercase character can match |
| ! | negation character | the oppsite of the matched pattern |
| \w | match a word, similar to [a-zA-Z0-9] | |
| \d | match an integer number, similar to [0-9] | |
| \d{3} | three matches of the preceding pattern | |
| \d{1, 3} | at least 1 match and at most 3 matches |
MOD_REWRITE VARIABLES
The Mod_Rewrite Variables Cheatsheet provides useful resources in producing rewrite rules.
https://www.askapache.com/htaccess/mod_rewrite-variables-cheatsheet/
MOD_REWRITE
RewriteRule
RewriteEngine On
# Rule syntax:
# RewriteRule Pattern Substituition [flag,...]
# Where Pattern is the input URL that is matched
# Where Substitution is the replacement or revision to the URL
# Where flag is a series of behaviur options for mod_rewrite
RewriteRule ^boats/([0-9])+$ http://myboats.com/boats/$1 [L]
# the domain of the Pattern http://mysite.com is implicit.
# OR
RewriteRule ^boats/(\d+)$ http://myboats.com/boats/$1 [C]
RewriteRule ^([a-zA-Z]+)/(\d+)$ http://myboats.com/products/$1/$2 [L]
# [C] - chain rules
# [L] - last ruleRewriteCond
RewriteEngine On
# RewriteCond Test Pattern [flag,...]
# Where Test is a string with or without variables like %{REQUEST_URI}
# Where Pattern is the Regular Expression test for string match
# Where flag is a series of behaviur options for mod_rewrite
# For more than 1 condition, all conditions must be true for running the rewrite rule.
RewriteCond %{HTTP_HOST} ^www\.my(\w+)\.com$ [NC]
RewriteCond %1 !^boats$
# The %1 refers to the first grouping in the previous condition test.
RewriteRule ^([a-zA-Z]+)/(\d+)$ http://myboats.com/products/$1/$2 [L]
# [C] - chain, where output of one rule becomes the input of the next
# [L] - last rule
# [NC] - no case (i.e., case insensitive)
# [OR] - or conditionRewriteBase
The first file is /var/www/mysite/index.html
The second file is /var/www/mysite/boats/boats.html
if we want to redirect index.html to boats.html, we could write:
RewriteRule ^index\.html$ /boats/boats.html
If we change the RewriteBase to /boats, the rule can be simplfied as:
RewriteBase /boats
RewriteRule ^index\.html$ boats.html [L]