Linux Text Management tool SED

sed [OPTION] ... ' Script ' [Input-file] ...

Script

Address Delimitation Edit Command

Common options:

-N: does not output the contents of the mode space to the screen;

-e script,--expression=script: multi-point editing;

-f/path/to/sed_script_file

One edit command per line;

-R,--regexp-extended: supports the use of extended regular expressions;

-i[suffix],--in-place[=suffix]: Directly edit the original file;

~]# sed-e ' [email protected]^#[[:space:]]*@@ '-e '/^uuid/d '/etc/fstab

Address delimitation:

(1) Empty address: To deal with the full text;

(2) Single address:

#: Specify line;

/pattern/: Each row that is matched by this pattern;

(3) Address range

#,#：

#,+#:

#,/pat1/

/pat1/,/pat2/

$: last line;

(4) Step forward: ~

: All Odd lines

2~2: All even lines

Edit command:

D: Delete;

P: Displays the contents of the mode space;

A \text: Append the text "text" After the line, support using \ n to implement multi-row append;

I \text: Insert text "text" in front of line, support using \ n to implement multiline insertion;

C \text: Replace the matched line with the text "text" specified here;

W/path/to/somefile: Saves the line of pattern space to the specified file;

R/path/from/somefile: Reads the contents of the specified file to the current file by the pattern to match the line, file merge;

=: Prints the line number for the line to which the pattern matches;

!: conditional inversion;

Address delimitation! Edit command;

s///: Find replacement, its delimiter can be self-specified, commonly used have [email protected]@@, s## #等;

Replace tag:

G: global substitution;

W/path/to/somefile: Saves the result of the substitution success to the specified file;

P: Shows the successful replacement line;

Exercise 1: Remove all white-space characters from the beginning of all lines in the/boot/grub/grub2.cfg file that begin with a blank character;

~]# sed ' [email protected]^[[:space:]]\[email protected]@ '/etc/grub2.cfg

Exercise 2: Remove all white-space characters from the beginning of the line at the beginning of the lines in the/etc/fstab file, preceded by #, and #;

~]# sed ' [email protected]^#[[:space:]]*@@ '/etc/fstab

Exercise 3: Output an absolute path to the SED command and take out its directory, which behaves like dirname;

~]# echo "/var/log/messages/" | Sed ' [Email protected][^/]\+/\[email protected]@ '

~]# echo "/var/log/messages" | Sed-r ' [Email protected][^/]+/[email protected]@ '

Advanced Editing Commands:

H: The content of the pattern space is covered in the holding space;

H: Append the contents of the pattern space to the holding space;

G: To cover the contents of the holding space in the pattern space;

G: Append the contents of the holding space to the pattern space;

x: Swap the content in the pattern space with the content in the hold space;

N: Overwrites the next line of the row to the pattern space in the read match;

N: Append the next line of the row to the pattern space to read;

D: Delete rows in the pattern space;

D: Delete all rows in multi-line mode space;

Example:

Sed-n ' n;p ' FILE: shows even rows;

Sed ' 1! G;h;$!d ' file: Displays the contents of the files in reverse order;

Sed ' $!d ' FILE: Take out the last line;

Sed ' $! n;$! D ' file: Two lines after removing the file;

Sed '/^$/d; G ' FILE: Delete all of the original blank lines, and then add a blank line after all the non-blank lines;

Sed ' n;d ' FILE: Displays odd lines;

Sed ' G ' FILE: Adds a blank line behind the original line;

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Linux Text Management tool SED