Linux: the regular expressions used and matched by grep

POSIX character entity: [: entity name:]:

[: Alpha:], [: lower:], [: Upper:]: letter, lower case letter, upper case letter

[: Digit:], [: xdigit:]: decimal number, hexadecimal number

[: Alnum:]: letters, numbers

[: Punct:]: punctuation

[: Space:]: blank (space, tab, new line)

[: Graph:]: printable character, non-control character, not including spaces!

[: Print:]: printable character, non-control character, including space, [:], [:],

[: Cntrl:]: Control Character

 

Several modes:

-G basic regular expression mode: default mode! : ^, $ ,., *, [], [^], \ W, \ W, \ <, \>, \ (\), X \ {M \}, X \ {M, \}, X \ {M, N \}, \ B .. \ B

-E extension mode: supported: + ,? , |, (|), X {m}, X {M,}, X {m, n} extension Modes

-F fixed naming string mode:

-P Perl extension mode:

 

Several options:

-I case-insensitive:

-W word match, not character match: equivalent to the pattern '\ B searched word \ B'

-X-line Matching:

-V reverse matching:

 

Input parameter settings:

-E | -- Regexp: Specifies a regular expression.

-F | -- file: Specifies the file to be searched.

-R |-r | -- Recursive: round-robin processing of files in the directory

-- Include = file_pattern: Only search for the specified file

-- Exclude = file_pattern: exclude the specified file from search.

-- Exclude-from = file: search for a specified file based on the content of the file.

-- Exclude-Dir = dir_pattern: exclude the specified folder for search.

-C | -- count: print only the number of matched rows instead of the actual row content. Note: This option provides output for each input file. Can be used together-

Option to count the number of unmatched rows!

-L: only print the name of the file that matches the pattern.

-L: only prints the names of files that do not match the pattern.

-M n (n is a non-negative integer) | -- Max-count n (n is a non-negative integer): After processing n matches for each file, the subsequent processing is stopped.

 

 

 

How to handle binary files:

-- Binary-files = {Binary| Text | without-match}: the binary file is processed as a binary file by default. Grep prints a line of information, prompting whether the mode is matched!

-A | -- text | -- Binary-files = text: WhenCompositionProcess this file

-I | -- Binary-files = without-match: the binary file is considered as mismatched!

 

 

Output format settings:

-O | -- only-matching: only prints the string that matches the pattern.

-N | -- line-number: print the row number:

-H print file name: default action. You can use the "-h" option to cancel this action.

-- Color | -- color: The character pattern that is highlighted.

-A n (n is a non-negative integer): print the N rows after the matching mode at the same time.

-B n (n is a non-negative integer): print the N rows before the matching mode at the same time.

-C | -- Context n (n is a non-negative integer) |-n (n is a non-negative integer): print the N rows before and after the matched pattern.

-C | -- count: print only the number of matched rows instead of the actual row content. Note: This option provides output for each input file. Can be used together-

Option to count the number of unmatched rows!

-L: only print the name of the file that matches the pattern.

-L: only prints the names of files that do not match the pattern.

-S | -- no-messages: do not print error messages

-B,-u: print the offset byte characters of the matching string.