What is Sed?
Sed is a stream editing tool for filtering and replacing text. Sed processes certain instructions by reading only one line at a time, so Sed is more suitable for processing large data files.
Sed reads the file content through a file or pipe, but Sed does not modify the source file by default, but copies the read content into the buffer, that is, the pattern space. All instruction operations are performed in the pattern space, and then Sed Process the content in the pattern space according to the corresponding instructions and output the result, which is output to the screen by default.
What are the common operations of Sed?
- a - Append after the specified line
- i - insert at the specified line
- d - delete the specified line
- s - replace the specified line
s command substitution
We use the following text for demonstration:
$ cat pets.txt
This is my cat
my cat's name is betty
This is my dog
my dog's name is frank
This is my fish
my fish's name is george
This is my goat
my goat's name is adamReplace the my string with Hao Chen's, the following statement should be well understood (s means replacement command, /my/ means match my, /Hao Chen's/ means replace the match with Hao Chen's, /g means replace on a line all matches):
$ sed "s/my/Hao Chen's/g" pets.txt
This is Hao Chen's cat
Hao Chen's cat's name is betty
This is Hao Chen's dog
Hao Chen's dog's name is frank
This is Hao Chen's fish
Hao Chen's fish's name is george
This is Hao Chen's goat
Hao Chen's goat's name is adamNote:
If you want to use single quotes, then you can't escape through \', you can use double quotes, and you can use \" to escape within double quotes.
Note:
the above sed does not correct The content of the file changes, just output the processed content. If you want to write back to the file, you can use redirection, such as:
$ sed "s/my/Hao Chen's/g" pets.txt > hao_pets.txtOr use the -i parameter to directly modify the file content:
$ sed -i "s/my/Hao Chen's/g" pets.txtAdd something at the beginning of each line:
$ sed 's/^/#/g' pets.txt
#This is my cat
# my cat's name is betty
#This is my dog
# my dog's name is frank
#This is my fish
# my fish's name is george
#This is my goat
# my goat's name is adamAdd something at the end of each line:
$ sed 's/$/ --- /g' pets.txt
This is my cat ---
my cat's name is betty ---
This is my dog ---
my dog's name is frank ---
This is my fish ---
my fish's name is george ---
This is my goat ---
my goat's name is adam ---Replace my in the third line with Your:
$ sed "3s/my/your/g" pets.txt
This is my cat
my cat's name is betty
This is your dog
my dog's name is frank
This is my fish
my fish's name is george
This is my goat
my goat's name is adamReplace only the text in lines 3 to 6:
$ sed "3,6s/my/your/g" pets.txt
This is my cat
my cat's name is betty
This is your dog
your dog's name is frank
This is your fish
your fish's name is george
This is my goat
my goat's name is adamSubstitute the text to continue:
$ cat my.txt
This is my cat, my cat's name is betty
This is my dog, my dog's name is frank
This is my fish, my fish's name is george
This is my goat, my goat's name is adamReplace only the first s of each line:
$ sed 's/s/S/1' my.txt
ThiS is my cat, my cat's name is betty
ThiS is my dog, my dog's name is frank
ThiS is my fish, my fish's name is george
ThiS is my goat, my goat's name is adamReplace only the second s of each line:
$ sed 's/s/S/2' my.txt
This iS my cat, my cat's name is betty
This iS my dog, my dog's name is frank
This iS my fish, my fish's name is george
This iS my goat, my goat's name is adamReplace the 3rd and later s of each line:
$ sed 's/s/S/3g' my.txt
This is my cat, my cat'S name iS betty
This is my dog, my dog'S name iS frank
This is my fiSh, my fiSh'S name iS george
This is my goat, my goat'S name iS adama command and i command
The a command is append, the i command is insert, and they are used to add lines. Such as:
# 其中的1i表明，其要在第1行前插入一行（insert）
$ sed "1 i This is my monkey, my monkey's name is wukong" my.txt
This is my monkey, my monkey's name is wukong
This is my cat, my cat's name is betty
This is my dog, my dog's name is frank
This is my fish, my fish's name is george
This is my goat, my goat's name is adam
# 其中的1a表明，其要在最后一行后追加一行（append）
$ sed "$ a This is my monkey, my monkey's name is wukong" my.txt
This is my cat, my cat's name is betty
This is my monkey, my monkey's name is wukong
This is my dog, my dog's name is frank
This is my fish, my fish's name is george
This is my goat, my goat's name is adamWe can use matching to add text:
# 注意其中的/fish/a，这意思是匹配到/fish/后就追加一行
$ sed "/fish/a This is my monkey, my monkey's name is wukong" my.txt
This is my cat, my cat's name is betty
This is my dog, my dog's name is frank
This is my fish, my fish's name is george
This is my monkey, my monkey's name is wukong
This is my goat, my goat's name is adamd command
delete matching lines
$ sed '/fish/d' my.txt
This is my cat, my cat's name is betty
This is my dog, my dog's name is frank
This is my goat, my goat's name is adam
$ sed '2d' my.txt
This is my cat, my cat's name is betty
This is my fish, my fish's name is george
This is my goat, my goat's name is adam
$ sed '2,$d' my.txt
This is my cat, my cat's name is bettyN command (incorporate the content of the next line as a buffer for matching)
The following example will include even-numbered lines in the original text into odd-numbered lines to match, while s is only matched and replaced once, so the following result:
$ sed 'N;s/my/your/' pets.txt
This is your cat
my cat's name is betty
This is your dog
my dog's name is frank
This is your fish
my fish's name is george
This is your goat
my goat's name is adamThat is, the original file becomes:
This is my cat\n my cat's name is betty
This is my dog\n my dog's name is frank
This is my fish\n my fish's name is george
This is my goat\n my goat's name is adamIn this way, the following example you will understand
$ sed 'N;s/\n/,/' pets.txt
This is my cat, my cat's name is betty
This is my dog, my dog's name is frank
This is my fish, my fish's name is george
This is my goat, my goat's name is adamc command
The c command is to replace the matching line
$ sed "2 c This is my monkey, my monkey's name is wukong" my.txt
This is my cat, my cat's name is betty
This is my monkey, my monkey's name is wukong
This is my fish, my fish's name is george
This is my goat, my goat's name is adam
$ sed "/fish/c This is my monkey, my monkey's name is wukong" my.txt
This is my cat, my cat's name is betty
This is my dog, my dog's name is frank
This is my monkey, my monkey's name is wukong
This is my goat, my goat's name is adamp command
print command, you can think of this command as a grep-style command
# 匹配fish并输出，可以看到fish的那一行被打了两遍，
# 这是因为sed处理时会把处理的信息输出
$ sed '/fish/p' my.txt
This is my cat, my cat's name is betty
This is my dog, my dog's name is frank
This is my fish, my fish's name is george
This is my fish, my fish's name is george
This is my goat, my goat's name is adam
# 使用n参数就好了
$ sed -n '/fish/p' my.txt
This is my fish, my fish's name is george
# 从一个模式到另一个模式
$ sed -n '/dog/,/fish/p' my.txt
This is my dog, my dog's name is frank
This is my fish, my fish's name is george
#从第一行打印到匹配fish成功的那一行
$ sed -n '1,/fish/p' my.txt
This is my cat, my cat's name is betty
This is my dog, my dog's name is frank
This is my fish, my fish's name is georgeReference link = https://coolshell.cn/articles/9104.html