Summary of basic usage of command line editor sed

1. summary

sed It's a kind of linux Command line editor . When dealing with text ,sed Store the currently processed rows in a temporary buffer , be called “ Mode space ”, then sed Command to process the contents of the buffer , When finished, output the contents of the buffer to standard output , Next process the following lines , Until the end of the file . sed Mainly used to automatically edit one or more files , Simplify the repeated operation of files .

2. sed Introduce

2.1. Parameters

sed Arguments to the command

Parameters	function
-n	Use quiet mode , Only the processed rows are displayed
-e	Directly in command line mode sed Editing of actions
-f	Run... In the specified file sed command
-r	Support extended regular syntax （ Otherwise, only the basic syntax is supported ）
-i	Modify the document directly , Instead of just exporting to standard output

2.2. function

sed Functions that commands can use

function	function
a	Add a new string to the next line
c	replace n1,n2 Between the lines
d	Delete n1,n2 Between the lines
i	Insert the string to the previous line
p	Print the specified column
s	Replace the specified string with another specified string

3. newly added 、 Delete row

3.1. Delete row

The following shows how to delete 2 To 5 That's ok .

nl /etc/passwd | sed '2,5d'

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As mentioned above ,d Function is used to delete （ For example clarity , use first nl The command lists the line numbers of the text ）, therefore , This command deletes 2 To 5 That's ok .

so , The first 2 To 5 The row has been deleted .

that , Just delete the second 2 Line? ？

nl /etc/passwd | sed '2d'

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Delete the first 3 To the last line ？

nl /etc/passwd | sed '3,$d'

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3.2. New row

The following shows that in the 2 Add after the line ’drink tea’

nl /etc/passwd | sed '2a drink tea'

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that , How to add data to the 2 OK, ahead ？

nl /etc/passwd | sed '2i drink tea'

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But , How to add two lines .

nl /etc/passwd | sed '2a Drink tea or ......\
> drink beer ?'

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4. Line replacement and display

The following shows how to 2 To 5 Replace the line with ’No 2-5 line’

nl /etc/passwd | sed '2,5c No 2-5 line'

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The following shows how to display only the 5-7 The method .

nl /etc/passwd | sed -n '5,7p'

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5. Data search

Find files that contain root Keyword line .

nl /etc/passwd | sed '/root/p'

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But , It doesn't seem to get the result we want , That's because the rows found are mixed with other rows , Confusing query results , At this time, the parameters must be passed -n Specifies the silent mode display .

nl /etc/passwd | sed -n '/root/p'

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6. Find and delete data

Delete /etc/passwd All contain root The line of .

nl /etc/passwd | sed '/root/d'

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7. Find and replace data

nl /etc/passwd | sed -n '/root/{s/bin/replace/;p}'

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First sed Found... In silent mode root character string , Then the code in braces is executed . sed ’s/ String to be replaced / New string /g’ This command replaces the string with another specified string .

8. Multi point editing

The above command performs the search first , Then the replacement command is executed , Name executes the print command p. that , How to execute multiple in one command sed Orders ？

nl /etc/passwd | sed -e '3,$d' -e 's/bash/blueshell/'

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-e Parameter indicates multipoint editing , That is to say, the... Is deleted first 3 Line to the end of the file , And then the remaining lines of bash Replace with blueshell.

9. Directly modify the contents of the document

All the above operations output the results to the standard output . adopt -i Parameters , You can modify the contents of the file directly . however , This operation is very dangerous , Although it is very convenient in many times , But be careful before using .