SED learning Summary of common commands under Linux

• sed function Description:

SED is a powerful text file processing tool for Linux, which can be used to add, delete, find, query, and match regular expressions to meet the needs of the work. It is also a core skill that an OPS person must master.

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• SED regular Expressions:

^ Match Line start

$ Match Line End

. Any character that matches a non-line break

* Match 0 or more characters

[] matches a character within a specified range

[^] matches a character that is not within the specified range

\(.. \) matches the substring, saves the matching characters, and gives the \ n reference to the replacement command s

& Save Search characters to replace other characters, to replace the & reference of the command s

X\{m\} repeat character x,m times

X\{m,\} repeat character x, at least m times

X\{m,n\} repeat character x, at least m times, no more than n times

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• SED command format:

sed [options] ' Range/Command ' file

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Common options:

-n displays only the matched content, usually with the P-parameter configuration.

-e executes multiple commands at the same time, another implementation: ' Command 1; command 2 '

-I executes the command and actually modifies the file, and if you do not use this option, all of the operations of SED simply modify the values in memory.

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• Common range:

1: Match line 1th

1,5: Matches line 1th to line 5th

2,$: Matches line 2nd to last 1 rows

: Match cardinality line, 2 indicates step value

2~2: Number of spouses, 2 indicates step value.

/string/: Matches a row that contains a string

/[a-z]/: Matches a row that contains a range

/^string/: Matching rows containing meta-character sets

/Regular/: Rows matching the contents of the regular expression

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• Common commands:

s replaces the specified content format: '/range/s/replace content/new content/replace range '

A\ Insert text Format below line: ' Range a\ content '

I\ Insert text Format above line: ' Range i\ content '

C\ to change the selected line to a new text format: ' Range c\ content '

d Delete the selected row format: ' Range d '

H copy content to buffer format: ' range h '

G Get buffer contents and append format: ' Range g '

P Print File Content format: ' range/Command/P '

R reads the file contents after the range format: ' Range/R file '

W Extract the contents of the range into file format: ' Range/w file '

! Match the content format to the inverse of the range: ' Range! '

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• Replace command s common parameters:

/delimiter format: '/' If the old value contains '/', you can modify/Be @ or # or |

G Replace range, n denotes the first match format: ' range/s/old value/new value/ng ' No n means replace all

\ n refers to the substring, which indicates the number of substring formats: ' Range/s/* substring */\n/g ' * indicates other content

& Quote ' # ' content format: ' Range/s/#/*&*/g ' #表示匹配内容

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Examples of regular expressions:

/^#/matches all lines beginning with #

/sh$/matches all rows ending with sh

/s.d/match S followed by an arbitrary character, D

/s*ed/matches 0 or more rows of S-connected Ed

/[0-9]/matches rows that contain numbers

/[a-z]/! Match lines that do not contain letters

/[^a-z]/matches lines that do not contain full letters

/\ (sh\) ell/#\1#/matching shell replaced by #sh#

/shell/*&*/match Shell replaced with *shell*

/s\{5\}/matches a row with 5 s

/s\{5,\}/matches a row with at least 5 s

/s\{5,10\}/matches the line of 5~10 s

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Examples of common options:

Show only the 1th line that matches to: sed-n ' 1p '/etc/passwd

Execute multiple commands simultaneously: sed-n-e ' 1p '-e '/mysql/p '/etc/passwd or sed-n ' 1p;/mysql/p '/etc/passwd

Execute the command and modify the original file: Sed-i ' 2d '/etc/rc.local

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Examples of common scopes:

Match line 1th: sed-n ' 1p '/etc/passwd

Match line 1th to 5th: Sed-n ' 1,5p '/etc/passwd

Match line 2nd to last 1 lines: Sed-n ' 2, $p '/etc/passwd

Match odd line: Sed-n ' 1~2p '/etc/passwd

Number of spouses: sed-n ' 2~2p '/etc/passwd

Match the line containing MySQL: sed-n '/mysql/p '/etc/passwd

Match lines starting with a/b/c: Sed-n '/^[a-c]/p '/etc/passwd

Match the line starting with root: Sed-n '/^root/p '/etc/passwd

Match 5 plus at least 2 rows of 0: Sed-n '/50\{2,\}/p '/etc/passwd

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Examples of common commands:

Match logon permissions for lines that contain the beginning of MySQL: Sed-n '/^mysql/[email protected]/bin/[email protected]/sbin/[email protected] '/etc/passwd

Match the 1th line of the file and insert ###### before the row: sed ' 1i\###### '/etc/passwd

Match the 1th line of the file and insert ###### after the row: sed ' 1a\###### '/etc/passwd

Match the 2nd line of the file and modify it to ######: sed ' 2c\###### '/etc/rc.local

Match the 2nd line of the file and delete the content: sed ' 2d '/etc/rc.local

Copy the 2nd line of the file and append to the last 1 lines: sed ' 2h; $G '/etc/rc.local

Read RESOLV content appended to local last 1 lines: sed ' $r/etc/resolv.conf '/etc/rc.local

Reads the local 3rd to 5th line to write to Newfile:sed-n ' 3,5w newfile '/etc/rc.local

Match file does not contain empty line contents: Sed-n '/^$/!p '/etc/rc.local

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Examples of common parameters for the Replace command s:

Modify the delimiter according to the actual situation: sed ' [email protected]#!/bin/[email protected]#!/bin/[email protected] '/etc/rc.local

Start replacement after 2nd match: Echo Shellshellshell |sed ' s/shell/shell/2g '

Extract substring and replace with reverse reference: Echo Test is ABc or 111 |sed ' s/\ ([a-z]\{3\}\) or \ ([0-9]*\)/*\2* or #\1#/'

Keep the search to the content and reference: Echo this is test file |sed ' s/test/##&##/'

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Attention:

When SED handles the replace operation in the script, if the new content is a reference variable, you need to change the single quotation mark to double quotation marks

Example:

name=123456

echo "# # # #6543210 # # # |sed-n" s/[0-9]\+/$name/P "

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This article comes from the "Damned Tenderness" blog, so be sure to keep this source http://lsong.blog.51cto.com/2432419/1922121

SED learning Summary of common commands under Linux