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It is believed that many inexperienced people have no idea about how to use sed text processing commands in Linux. Therefore, this paper summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

Sed's handling of text is very powerful, and the sed is very small, few parameters, easy to grasp, his way of operation is a bit like root awk. Sed reads files sequentially, line by line. It then performs all the operations specified for the row, and the contents are displayed after the requested modification is completed, or it can be stored in a file. After completing all the operations on one line, it reads the next line of the file and then repeats the process until it finishes the file. It is important to note here that the source file (by default) remains unmodified. Sed reads the entire file by default and modifies each line in it. To put it bluntly, it is a line-by-line operation.

Parameters.

Sed-h

-n,-- quiet,-- silent cancel automatic printing mode space

-e script,-- expression= script adds "script" to the running list of the program

-f script file,-- file= script file adds "script file" to the running list of the program

-- follow-symlinks follows soft links when modifying files directly

-I [extension],-- in-place [= extension] modify the file directly (back up the file if you specify the extension)

-l N,-- line-length=N specifies the expected length of line breaks for the "l" command

-- posix closes all GNU extensions

-r,-- regexp-extended uses extended regular expressions in scripts

-s,-- separate treats the input file as a separate file rather than a long continuous input

-u,-- unbuffered reads the least data from the input file and refreshes the output more frequently

-- help print help and exit

-- version outputs version information and exits

Example 1

Test file

The code is as follows:

Root:x:0:0:root:/root:/bin/bash

Bin:x:1:1:bin:/bin:/bin/false

Daemon:x:2:2:daemon:/sbin:/bin/false

Mail:x:8:12:mail:/var/spool/mail:/bin/false

Ftp:x:14:11:ftp:/home/ftp:/bin/false

& nobody:$:99:99:nobody:/:/bin/false

Zhangy:x:1000:100:,:/home/zhangy:/bin/bash

Http:x:33:33::/srv/http:/bin/false

Dbus:x:81:81:System message bus:/:/bin/false

Hal:x:82:82:HAL daemon:/:/bin/false

Mysql:x:89:89::/var/lib/mysql:/bin/false

Aaa:x:1001:1001::/home/aaa:/bin/bash

Ba:x:1002:1002::/home/zhangy:/bin/bash

Test:x:1003:1003::/home/test:/bin/bash

@ zhangying:*:1004:1004::/home/test:/bin/bash

Policykit:x:102:1005:Po

Example a, this example, replaces root in the test file with tankzhang, but only once and terminates the operation on this line, go to the next line

The code is as follows:

[zhangy@BlackGhost mytest] # sed's Universe rootUniverse tankzhang test | grep tank

Tankzhang:x:0:0:root:/root:/bin/bash

Example b, in this example, replace all the root in the file test with tankzhang. Please note the letter g, the abbreviation of global.

The code is as follows:

[zhangy@BlackGhost mytest] # sed's test rootbank Tankzhang test | grep zhang

Tankzhang:x:0:0:tankzhang:/tankzhang:/bin/bash

Zhangy:x:1000:100:,:/home/zhangy:/bin/bash

Ba:x:1002:1002::/home/zhangy:/bin/bash

@ zhangying:*:1004:1004::/home/test:/bin/bash

Example c, adding-n p means that only those lines that are replaced (partial substitution) are printed. In the above example, I did not add grep.

The code is as follows:

[zhangy@BlackGhost mytest] # sed-n's test

Tankzhang:x:0:0:root:/root:/bin/bash

Example d, adding-n pg means that only those lines that are replaced (all replace) are printed. In the above example, I did not add grep.

The code is as follows:

[zhangy@BlackGhost mytest] # sed-n's test

Tankzhang:x:0:0:tankzhang:/tankzhang:/bin/bash

Example e, between the second and eighth lines, replace the line that begins with zhang, replace it with ying, and display the replaced line

The code is as follows:

[zhangy@BlackGhost mytest] # cat test | sed-ne '2Jing 8s / ^ Zhang / ying/gp'

Yingy:x:1000:100:,:/home/zhangy:/bin/bash

Example f, when there are multiple commands to be executed, can be separated by a semicolon, and the delimiter can be customized, the default is /. The above example means that between the second and eighth lines, replace the line that begins with zhang, replace it with ying, between 5 and 10, replace dbus with goodbay, and display the replacement line.

The code is as follows:

[zhangy@BlackGhost mytest] # cat test | sed-n '2Jing 8s / ^ Zhang / ying/gp;5,10s#dbus#goodbay#gp'

Yingy:x:1000:100:,:/home/zhangy:/bin/bash

Goodbay:x:81:81:System message bus:/:/bin/false

Example g, the root of this example is the same as the example above, except that-e acts as a semicolon, and-e can also split multiple commands.

The code is as follows:

[zhangy@BlackGhost mytest] # cat test | sed-ne '2ZHANGCHANGCHANGCHAGING GPP'-ne'5 10s recording dbushes goodbayhands gp'

Yingy:x:1000:100:,:/home/yingy:/bin/bash

Goodbay:x:81:81:System message bus:/:/bin/false

Example h, regular usage, add\ if you use parentheses in sed, otherwise you will report an error.

The code is as follows:

[zhangy@BlackGhost mytest] # sed-ne '2jiggle 8s / ^\ (zhangy\) /\ 1ingAccord gp' test

Zhangying:x:1000:100:,:/home/zhangy:/bin/bash

[root@masters ~] # sed-ne'2 recorder 8s / ^\ (zhangy\) / & ing/gp' test

Zhangying:x:1000:100:,:/home/zhangy:/bin/bash

The use of izhang & is to add the string after & to the string found, and ying after the string.

The code is as follows:

[zhangy@BlackGhost mytest] # sed-ne'2 relegation 15s ZHANGCHANGCHANGYINGG 'test

Zhangyingy:x:1000:100:,:/home/zhangyingy:/bin/bash

Ba:x:1002:1002::/home/zhangyingy:/bin/bash

@ zhangyingying:*:1004:1004::/home/test:/bin/bash

Example j, this example is to replace between lines starting with zhang and ending with lines that match Po

The code is as follows:

[zhangy@BlackGhost mytest] # sed-ne'/ ^ zhang/,/Po/s/zhang/ying/gp' test

Yingy:x:1000:100:,:/home/yingy:/bin/bash

Ba:x:1002:1002::/home/yingy:/bin/bash

@ yingying:*:1004:1004::/home/test:/bin/bash

Here n is the abbreviation of next. After finding the line of root, replace the bin in the next line with tank.

The code is as follows:

[zhangy@BlackGhost mytest] $sed'/ root/ {nbett _ Tank /} 'test

Root:x:0:0:root:/root:/bin/bash

Tank:x:1:1:bin:/bin:/bin/false

The function of the example mpenery y is to change the matching character to uppercase, but the length of the replacement character is the same as that of the character to be replaced.

The code is as follows:

[zhangy@BlackGhost mytest] $sed-e'1 test 2y test

ROOT:x:0:0:ROOT:/ROOT:/bin/bash

Bin:x:1:1:bin:/bin:/bin/false

For example, the function of nQuery h is to put the found lines into a cache, and the function of G is to put the contents of the cache on the last line.

The code is as follows:

[zhangy@BlackGhost mytest] $sed-e'/ root/h'-e'$G' test

..

..

Ba:x:1002:1002::/home/zhangy:/bin/bash

Test:x:1003:1003::/home/test:/bin/bash

@ zhangying:*:1004:1004::/home/test:/bin/bash

Root:x:0:0:root:/root:/bin/bash

Example o, line substitution, replace the line matching root with the line matching zhangy

The code is as follows:

[zhangy@BlackGhost mytest] $sed-e'/ root/h'-e'/ zhangy/g' test

Root:x:0:0:root:/root:/bin/bash

Bin:x:1:1:bin:/bin:/bin/false

Daemon:x:2:2:daemon:/sbin:/bin/false

Mail:x:8:12:mail:/var/spool/mail:/bin/false

Ftp:x:14:11:ftp:/home/ftp:/bin/false

& nobody:$:99:99:nobody:/:/bin/false

Root:x:0:0:root:/root:/bin/bash

Http:x:33:33::/srv/http:/bin/false

Dbus:x:81:81:System message bus:/:/bin/false

Hal:x:82:82:HAL daemon:/:/bin/false

Mysql:x:89:89::/var/lib/mysql:/bin/false

Aaa:x:1001:1001::/home/aaa:/bin/bash

Root:x:0:0:root:/root:/bin/bash

Test:x:1003:1003::/home/test:/bin/bash

Root:x:0:0:root:/root:/bin/bash

Example p, this example is to replace between lines starting with zhang and ending with lines that match Po

The code is as follows:

[zhangy@BlackGhost mytest] # sed-ne'/ ^ zhang/,/Po/s/zhang/ying/gp' test

Yingy:x:1000:100:,:/home/yingy:/bin/bash

Ba:x:1002:1002::/home/yingy:/bin/bash

@ yingying:*:1004:1004::/home/test:/bin/bash

The example qforce 3Q means to exit on the third line.

The code is as follows:

[zhangy@BlackGhost mytest] $sed-e's Bintank test

Root:x:0:0:root:/root:/tank/bash

Tank:x:1:1:tank:/tank:/tank/false

Daemon:x:2:2:daemon:/stank:/tank/false

Example r, special matching

Don't forget that there is a square bracket outside the square brackets to match the numbers.

[: alnum:] alphanumeric [amurz Amurz 0-9]

[: alpha:] letter [amurz Amurz]

[: blank:] spaces or tabs

[: cntrl:] any control character

[: digit:] numbers [0-9]

[: graph:] any visual character (no spaces)

[: lower:] lowercase [amurz]

[: print:] non-control character

[: punct:] punctuation character

[: space:] Spac

[: upper:] uppercase [Amurz]

[: xdigit:] hexadecimal digits [0-9 amurf Amurf]

The code is as follows:

[zhangy@BlackGhost mytest] # sed-ne'2 sed 15s Dropzhangy.* [[: digit:]] / = / gp' test

=:,: / home/zhangy:/bin/bash

@ =:: / home/test:/bin/bash

Example 2

For example a, delete line 1Time14

The code is as follows:

[zhangy@BlackGhost test] $sed-e'1 test 14d'

@ zhangying:*:1004:1004::/home/test:/bin/bash

Policykit:x:102:1005:Po

For example b, delete the lines after 4, including line 4, and take $as the maximum number of lines.

The code is as follows:

[zhangy@BlackGhost mytest] $sed-e '4jade d' test

Root:x:0:0:root:/root:/bin/bash

Bin:x:1:1:bin:/bin:/bin/false

Daemon:x:2:2:daemon:/sbin:/bin/false

For example c, delete the line that includes false or the line that includes bash, and don't forget to add\

The code is as follows:

[zhangy@BlackGhost mytest] $sed-e'/\ (false\ | bash\) $/ d'test

Policykit:x:102:1005:Po

Example d, delete the line from the line that matches root to the line that matches the middle line that starts with test

The code is as follows:

[zhangy@BlackGhost mytest] $sed-e'/ root/,/ ^ test/d' test

@ zhangying:*:1004:1004::/home/test:/bin/bash

Policykit:x:102:1005:Po

Example 3

Example a, read the contents of test2 and write it to the bottom of the matching line

The code is as follows:

[zhangy@BlackGhost mytest] $sed-e'/ ^ root/r test2' test

Root:x:0:0:root:/root:/bin/bash

=

-

+

Bin:x:1:1:bin:/bin:/bin/false

Daemon:x:2:2:daemon:/sbin:/bin/false

Example b, write rows that match numbers into test2

The code is as follows:

[zhangy@BlackGhost mytest] $sed'/ [[: digit:]] / w test2' test

Example c, what you are going to insert, insert below the matching line

The code is as follows:

[zhangy@BlackGhost mytest] $sed'/ root/a\\ = = aaaa====' test

Root:x:0:0:root:/root:/bin/bash

= aaaa====

Bin:x:1:1:bin:/bin:/bin/false

Example d, exactly the opposite of root a, what is about to be inserted is inserted on top of the matching line.

The code is as follows:

[zhangy@BlackGhost mytest] $sed'/ ^ daemon/i\\ = 'test

Root:x:0:0:root:/root:/bin/bash

Bin:x:1:1:bin:/bin:/bin/false

=

Daemon:x:2:2:daemon:/sbin:/bin/false

Mail:x:8:12:mail:/var/spool/mail:/bin/false

Example 4

# get the parent directory of a file (or directory) path, swatches @ is the replacement format,\ (/. * /\) refers to a "/" followed by any character followed by a "/", where\ (\) is used to reference the matching content as a whole. [^ /]\ {1,\} means that a non-"/" character appears once, twice, or more times; /\? It means that "/" occurs 0 or 1 times, and\ 1 refers to the matching content in front of the backward reference.

The code is as follows:

[root@practice ~] # echo "/ usr/local/bin/" | sed's @\ (/. * /\) [^ /]\ {1,\} /\? @\ 1percent'

/ usr/local/

# after using extended regular expressions, you can do the same:

[root@practice ~] # echo "/ etc/rc.d/rc.sysinit" | sed-r's @ (/. * /) [^ /] + /? @\ 1regions'

/ etc/rc.d/

After reading the above, have you mastered how to use sed text processing commands in Linux? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

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