Sed line Editor

sed: line editor, which does not process source files by default.

-I directly modify the source file

-escript–e Script can execute multiple scripts simultaneously

-f/path/to/sed_script

sed–f/path/to/scripts file

- R: indicates the use of extended regular expressions

History |sed ' s/[[:space:]]//' use the sed command to delete the line space

1.sed ' Source address + edit Command ' file

Address:1,100

$ last line

$-1 Countdown second line

2 mode:/ Regular expression

/^root/

3 /mode 1/,/ mode 2/

4. Specify the line

5.starline+n N rows backward from Starline

d: Delete rows that match the criteria

sed ' 1,2d '/etc/fstab Delete the first row to the second row

sed '/oot/d '/etc/fstab delete the row containing the root

sed ' 1,+10d '/etc/fstab delete the first line and the following lines

P: displays rows that match the criteria.

sed '/\//p '/etc/fstab displays lines with a slash. The same will show 2 times

- N: show only rows that match the criteria

Sed-n '/root/p '/etc/passwd

a \ "string": appends a new line after the specified line with the contents "string"

sed '/root/a \# Hello World '/etc/passwd added after the line containing the root #helloworld

sed '/root/a \# Hello world \ #hello '/etc/passwd add 2 rows later

I \string: adds a new line before the specified line. Content is string

sed '/root/i\ #hello \ n #hello '/etc/passwd add 2 lines in front

r file adds the specified file contents to the qualifying line

sed ' 10r/etc/passwd '/etc/fstab add passwd content to line /etc/fstab

sed ' $ r/etc/passwd '/etc/fstab inserted in the last line after $ passwd

sed ' 1,2r/etc/issue '/etc/fstab inserts the contents of issue after the first and second lines

W Save content in specified range to specified file

sed '/oot/w/tmp/oot.txt '/etc/fstab oot in fstab save to /tmp/oot.txt

s find and replace:s/ What to look for ( support Regular expression )/ Replace with specified content (regular expression not supported)/

sed ' s/oot/oot/'/etc/fstab find oot in fstab replaced with oot

Regular expressions are supported:

sed ' s/^\//#/'/etc/fstab finds lines in Fstab , starting with / . and put / replace #

The default is to replace only the first occurrence of the character in each row

Add modifier g: Global substitution

Sed ' s/\//#/g '/etc/fstab

I: ignore case when finding

Sed ' s/oot/ooo/i '/etc/fstab

s///: s# #: [Email protected] @

Support references \ (\), \1 \2

sed ' s#l. E#&r#g ' sed.txt will sed in L. the word reference of E is replaced with 1..er

&: represents the entire string that the reference pattern matches to

or sed ' s#\(L. E\)#\1r#g ' Sed.txt

1. delete /etc/grub.conf whitespace characters at the beginning of this file

[Email protected]~] #sed ' s/^[[:space:]]//'/etc/grub.conf

2. Replace the number 5 in the "Id:3:initdefault:" line in the /etc/inittab file

[Email protected]~] #sed ' [email protected]\ (id:\) [0-9]\ (: initdefault:\) @\15\[email protected] '/etc/inittab

3. Delete blank lines in the /etc/inittab file

[[Email protected]~] #sed ' s/^$/d '/etc/inittab

4. delete the # number at the beginning of the /etc/inittab file and require that the white space character be followed by #

[Email protected]~] #sed-R ' s/^#[[:space:]]//'/etc/inittab

5. Remove a directory name for a file path

[Email protected]~] #echo "/etc/rc.d" |sed-r ' [email protected]^ (/.*/) [^/]+/[email protected]\[email protected] '

6. write a script to pass three, the first is an integer, the second is an operator, the third is an integer, the operation, the exact 2 decimal places

/bin/bash

#

echo "Scale=2;$1$2$3" |BC

7. write a script. Pass three parameters to compare size

/bin/bash

#

if [$1-gt $2];then

if [$3-gt$1];then

echo "$"

Else

echo "$"

Fi

Else

If [$3-gt $];then

echo "$"

Else

echo "$"

Fi

Fi

Sed line Editor