Shell --- The basic syntax of the grep command processing huge amounts of data

 grep command

• One shell script Three Musketeers

• grep scenarios: usually extracted line data

• Syntax: grep [options] [content] [file]

  • -v the content negated extract

  • -n display line numbers to extract the contents of

  • -w exact match

  • -i ignore case

  • ^ Matches the beginning of the line

  • -E regular match

• Regular grammar

Regular Expressions	description	example
\	Escape, the escape special characters, ignoring its special meaning	A . b match ab, but it can not be escaped to match ajb ,. special significance
^	Match the beginning of the line ^ it is the beginning of the string match	^ Tux tux match starts with the line
$	Matching end of the line, $ end of the string is	tux tux $ match to the end of the line
.	Matches any single newline character \ n other than	ab. match abc or bad, can not match abcd or abde, can only match a single character
[]	Match any one character is included in the [characters] among	coo [kl] matches cook or cool
[^]	Matches any character other than character	123 45 not matching 1235,1236,1237 or 1234 may be
[-]	With any one of the characters in the range [] is specified to be written is incremented	[0-9] 1, 2 or 3, matches any of a number
?	Before the match 1 or 0 times	olou? r matches color or colour, can not match colouur
+	Before the match 1 or more times	sa-6 + match sa-6, sa-666, does not match sa-
*	Before matches zero or more times	co * l matches cl, col, cool, coool etc.
()	Matching expression, create a substring for matching	ma (tri)? max match or maxtrix
{n}	N times before matching items, n being a positive integer is 0 can be	[0-9] {3} matches any three-digit number can be expanded to 0-9 [0-9]
{n,}	Prior to entry need to match at least n times	[0-9] {2} matches any two-digit or more bits
{n,m}	Before the specified items matching at least n times, matching up m times, n <= m	[0-9] {2,5} from two digits to match any of a five-digit number between
|	Alternating match | any of both sides	ab & (C | D) match abc or abd

 

• Common rules

description
* All characters
[Az] lowercase
[AZ] uppercase letters
[AZ] lowercase and uppercase letters
[0-9] Digital