| Character | Description |
| . | Matches any single character except a newline. |
| * | Matches zero or more occurences of the character immediately preceding it. |
| ? | Match any character one time, if it exists. |
| + | Match declared element one or more times. |
| {n} | Match declared element one or more times. |
| {n,} | Match declared element at least n times. |
| {n,N} | Match declared element at least n times, but not more than N times. |
| \b | Match at the beginning or end of a word. |
| \B | Match in the middle of a word. |
| [chars] | Matches any one of the characters given in chars, where chars is a sequence of characters. You can use - character to indicate a range of characters. |
| [^chars] | One occurance of any character that is not specified by chars is matched. |
| ^ | Matches the beginning of the line. |
| $ | Matches the end of a line. |
| \ | Treats the character that immediately follows the \ literally. This is used to specify patterns that contain one of the preceding wildcards. |
| (pattern1 | pattern2) | Matches pattern1 or pattern2. |
| \s | Match one space character. |
