正则表达式：
| Regex | Description | Example |
^ | The start-of-line marker | ^tux matches any line that starts with tux |
$ | The end-of-line marker | tux$ matches any line that ends with tux |
. | Matches any one character | Hack. matches Hack1, Hacki but not Hack12, Hackil; only one additional character matches |
[] | Matches any one of the character set inside [] | coo[kl] matches cook or cool |
[^] | Exclusion set: the carat negates the set of characters in the square brackets; text matching this set will not be returned as a match | 9[^01] matches 92, 93 but not 91 and 90 |
[-] | Matches any character within the range specified in [] | [1-5] matches any digits from 1 to 5 |
? | The preceding item must match one or zero times | colou?r matches color or colour but not colouur |
+ | The preceding item must match one or more times | Rollno-9+ matches Rollno-99, Rollno-9 but not Rollno- |
* | The preceding item must match zero or more times | co*l matches cl, col, coool |
() | Creates a substring in the regex match | Explained below, in the section “Substring match and back-referencing” |
{n} | The preceding item must match exactly n times | [0-9]{3} matches any three-digit number. This can be expanded as: [0-9][0-9][0-9] |
{n,} | Minimum number of times that the preceding item should match | [0-9]{2,} matches any number that is two digits or more in length |
{n, m} | Specifies the minimum and maximum number of times the preceding item should match | [0-9]{2,5} matches any number that is between two and five digits in length |
| | Alternation — one of the items on either side of | should match | Oct (1st|2nd) matches Oct 1st or Oct 2nd |
\ | The escape character for escaping any of the special characters given above | a\.b matches a.b but not ajb. The dot is not
interpreted as the special “match any one character” regex shown above,
but instead a literal dot (period) ASCII character is sought to be
matched. Another example: if you’re searching for the US currency symbol
“$”, and not the end-of-line marker, you must precede it with a
back-slash, like this: \$ |
http://www.opensourceforu.com/2011/04/sed-explained-part-1/
收藏：
匹配一个电子邮箱地址：
[A-Za-z0-9._]+@[A-Za-z0-9._]+\.[a-zA-Z]{2,4}
匹配HTTPURL的正则表达式：
http://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,4}
