Linux Learning Notes-The 12th lesson-shell Script's regular expression (i)

First, Grep,egrep,fgrep

1) grep

Format: grep [options] [mode] [file name]

Common options:-N: Display line numbers and matching rows

-V: Reverse match

-C: No matching rows are displayed, only the number of matching rows is displayed

-I: Ignore case

-R: Recursive search

-E: Supports extended regular expressions

-P: Support for Perl regular expressions

-F: Regular expressions are not supported, and patterns are matched by literal meaning

Example:

grep sample	Description
grep ' \<tom>\ ' file	Show rows that contain the word Tom
grep ' Tom Jerry ' file	Show a line containing ' Tom Jerry '
grep ' ^tommy ' file	Display lines starting with the Tommy string
grep ' \.bak$ ' file	Displays lines ending with. bak at the end of the line
grep ' [Pp]hoto ' *	Displays the file name of a photo or photo in all the file names of the current working directory
grep ' [A-z] ' file	Display a line with at least 1 uppercase letters
grep ' [0-9] ' file	Display a line with at least 1 digits
grep ' [A-z] ... [0-9] ' file	Displays lines that start with a capital letter and end with a number of 5 string patterns
Grep-w ' [tt]est ' file	Show rows that contain but test and test
Grep-s ' TY Kim ' file	Search for rows containing ' TY Kim ', but not displayed on screen
Grep-v ' Jerry ' file	Show all lines that do not contain ' Jerry '
Grep-i ' Sam ' file	Ignore uppercase and lowercase letters, showing all rows containing Sam
Grep-l ' Dear Boss ' *	Displays all file directories that contain ' Dear Boss '
Grep-n 'to M ' File	Display rows that contain Tom, along with line numbers
grep "$name" file	Displays all rows that have the value of the name variable. Double quotation marks ("") must be used when using variables
grep ' $ ' file	Displays the line that contains the ' $ $ ' character. The $ character within the single quotation mark is recognized as its own
PS aux | grep ' ^*multi '	Connect the display results of PS with the pipe character and grep, displaying all lines with a space at the beginning of the line and containing multi

2) Egrep

Egrep is the extension of grep and can be used with other wildcard characters

+: More than 1 characters

？ : There are 0 or 1 characters

A|b: Matches the character of A or b

(): Character Group

3) Fgrep

Similar to grep, the special characters and the $ characters are recognized as themselves

Ii. SED

Non-interactive text file editor

Common options:

-N: Cancel default output

-e: Allow multiple scripts to execute

-I: Modify the original file directly

-R: Using extended regular expressions

Example:

sed example	Meaning
8d	Delete line 8th of input
/^$/d	Delete all empty rows
1,/^$/d	Delete from the first line until a blank line is found
/jones/p	Show only rows that contain "Jones" (using the-n option)
s/windows/linux/	Replace the first occurrence of "Windows" with "Linux" on each line entered
S/windows/linux/g	Replace each occurrence of "Windows" with "Linux" on each line entered
s/*$//	Remove all whitespace at the end of a line
S/00*/0/g	Replace all consecutive occurrences of 0 with 0
/gui/d	Delete all rows that contain "GUI"
S/gui//g	Remove the "GUI" three characters from each line entered

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Linux Learning Notes-The 12th lesson-shell Script's regular expression (i)