Summary of common usage of grep in Linux

grep is the command of the Linux Chinese editing class to select the desired text content

Main format: grep [option] "PATTERN" FILENAME

Option:-I ignores case

-O displays only the characters that match

-V Reverse display (shows rows not matched to)

--color to display matching characters in color notation

"PATTERN": Supports RegExp (regular expression)

1, character matching:

. : Matches one character

[]: Character matching interval example: [A-z]

[^]: Character matching reverse interval example: [^a-z]

2. Number of character matches

*: Any number of common usage:. *: Any number of characters

\?: 0 or 1 times

\{m,n\}: At least m times, up to N times

\{1,\} at least 1 times

\{0,3\} 0-3 plays

3, anchor character

^: Anchoring the beginning of the line

$: Anchor Line End

\<: Anchor Word first

\>: Anchor ending

4. Grouping

\(.. \): Group Overall match for example: \ (ab\): With AB as a whole

Latter references: \1 \2 \3 characters in a group

\1: Represents a group in a forward reference to the first (to corresponding)

\2: Represents a grouping in a second "(to corresponding") reference

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Summary of common usage of grep in Linux