The following table shows RegEx commonly used in the htaccess file (by Hostwinds).
| Regex Character | Explanation |
| # | Forces the server to ignore the text following the # on the same line. Typically used for comments |
| [F] | Indicates Forbidden, with this the server should return a 403 forbidden error to the client |
| [L] | The Last rule forces the server to stop processing rules in the .htaccess file |
| [N] | Indicates Next and forces Apache to redo the rewrite process, except using the currently rewritten URL instead of the initial URL |
| [G] | Gone tells the server to deliever the gone status message, which is used to mark pages that no longer exist on the site. |
| [R] | This forces Apache to initialize a redirect, this can be a permanent redirect (page has moved, 301), or a temporary redirect (302). |
| [P] | Indicates Proxy which tells the server to use mod_proxy to handle requests |
| [C] | Tells the server to chain a rule with the next rule. If the rule matches for example, then the chained rules will run as well, if not, then they will not run. |
| [QSA] | Tells the server to use the query string at the end of an expression |
| [NC] | No Case instructs the server to treat any argument as case insensitive |
| [NS] | The No Subrequest forces the server to skip if it is an internal sub request |
| [PT] | Pass Through has mod_rewrite send a formatted URL back to Apache |
| [NE] | No Escape forces the server to parse through all output ignoring escaping characters, meaning spaces in the URL will not be replaced with %20 for example |
| [OR] | Specifies a logical ‘OR‘ statement that evaluates two expressions |
| [S=x] | Forces the server to skip “x” number of rules based on if a match is found, not the same as the Chain flag [C] |
| [a-z] | Denotes a range of characters between the two characters separated by a dash |
| [^] | Defines not within a character class, or the Start of a string of characters |
| []+ | Defines that any combination characters defined within the brackets is a match there can be multiple matches |
| [] | Defines that any characters defined within the brackets is a match |
| [T=MIME-type] | Defines the mime type, forces the target file to be that mime type |
| [E=variableName:newValue] | Forces the server to set the environmental variable “variableName” to the value “newValue” |
| a{n} | Defines the specific number of the preceding character to be matched |
| ? | Defines the preceding character as being optional |
| $ | Signals the end of a regular expression |
| () | Can be used to group characters together |
| ^ | Signals the beginning of a regular expression |
| . | Specifies a single arbitrary character |
| – | Signals not to perform an action |
| ! | Defines negation |
| + | Will match at least one preceding character |
| | | Logical ‘OR‘ operator |
| * | Wildcard that will match any occurrence of the preceding character |
| \. | Signals an escaped literal period |
| \ | Used to escape special characters |
| -d | Analyzes if a string exists within a directory |
| -f | Determines if a string is a preexisting file |
| -s | Tests for a non zero value |