Linux-sed-non-interactive text stream Editor

Linux-sed-non-interactive text stream Editor-general Linux technology-Linux programming and kernel information. For details, see the following. Introduction
Sed is a non-interactive text stream editor. It edits the copy of a file or standard input and export text.

Instance

1. Row matching
[Root @ mypc/] # sed-n '2p'/etc/passwd print 2nd rows
[Root @ mypc/] # sed-n '1, 3 P'/etc/passwd print 1st to 3rd rows
[Root @ mypc/] # sed-n' $ P'/etc/passwd print the last line
[Root @ mypc/] # sed-n'/user/'P/etc/passwd print the row containing the user
Rpc: x: 32: 32: Portmapper RPC user: // sbin/nologin
Rpcuser: x: 29: 29: RPC Service User:/var/lib/nfs:/sbin/nologin
[Root @ mypc/] # sed-n'/\ $/'p/etc/passwd print the row containing $ metacharacters, $ indicates the last row

2. Insert text and additional text (insert a new line)
[Root @ mypc/] # sed-n'/FTP/P'/etc/passwd print the FTP row
Ftp: x: 14: 50: FTP User:/var/ftp:/sbin/nologin
[Root @ mypc/] # sed '/FTP/a \ 100'/etc/passwd Insert a new row after the row containing FTP, with the content 456
[Root @ mypc/] # sed '/FTP/I \ 123'/etc/passwd Insert a new row before the row containing FTP, with the content 123
[Root @ mypc/] # sed '/FTP/I \ "123"'/etc/passwd Insert a new row before the row containing FTP with the content of "123 ″
[Root @ mypc/] # sed '5 a \ 100'/etc/passwd Insert a new row after row 123 with the content of 5th
[Root @ mypc/] # sed '5 I \ "12345" '/etc/passwd Insert a new row before row 5th with the content "12345 ″

3. delete text
[Root @ mypc/] # sed '1d '/etc/passwd Delete row 1st
[Root @ mypc/] # sed '1, 3d '/etc/passwd Delete lines 1st to 3
[Root @ mypc/] # sed '/user/D'/etc/passwd Delete row with user

4. Replace the text. Replace the command with the replacement mode to replace the specified mode. The format is:
[A d r e s [, address] s/pattern-to-find/replacement-pattern/[g p w n]
[Root @ mypc/] # sed's/user/USER/'/etc/passwd: replace 1st users with user, and g indicates global replacement.
[Root @ mypc/] # sed's/user/USER/G'/etc/passwd replace all users with user
[Root @ mypc/] # sed's/user/# user/'/etc/passwd: replace 1st users with # user, for example, used for shielding
[Root @ mypc/] # sed's/user // '/etc/passwd: replace 1st users with null
[Root @ mypc/] # sed's/user/& 11111111111111/'/etc/passwd if you want to append or modify a long string, you can use the (&) command,
& Save the discovery mode of the command to call it again, and put it in the replacement string. Here we put & above
[Root @ mypc/] # sed's/user/11111111111111 &/'/etc/passwd here will be placed behind

5. A quick command line
Below are some command lines. ([] Indicates space, [] indicates t a B key)
'S/\. $ // G' Delete the row ending with a period
'-E/abcd/d': Delete the row that contains a B c d.
'S/[] [] [] */[]/G' Delete more than one space and replace it with one space
'S/^ [] [] * // G' Delete the first space in the row
'S/\. [] [] */[]/G' deletes a period followed by two or more spaces, replacing it with a space.
'/^ $/D' Delete empty rows
'S/^. // G' Delete the first character
'S/COL \ (... \) // G' Delete the last three letters followed by C O L
'S/^ \ // G' Delete the first \ from the path \
'S/[]/[] // G' delete all spaces and replace them with the t a B key.
'S/^ [] // G' delete all t a B keys at the beginning of the row
'S/[] * // G' delete all t a B keys
If you use s e d to filter files, it is best to divide the problem into several steps, perform the step by step, and execute the test results.