How to delete a string with the same word and consecutively increasing number in a text file using a shell script?

Question

For example I have:

Hello1 :
Hello2 : 
Hello3 :

How Could I delete all of these with a shell script. The number reaches up all the way to 1000.

Answer 1

sed -i '/^Hello[[:digit:]]\+\>/d' file.txt

或者，如果要输出到其他文件：

sed '/^Hello[[:digit:]]\+\>/d' file.txt > newfile.txt

Answer 2

If you wish to delete all the lines that contain only Hello(number) : use below :

Sample Input in file

Hell
Hello1 :
No hello stuff here
Unjulating stuff
Hello2 :
Some sentence
Hello99 :

Script

sed -Ei '/^Hello[[:digit:]]+ :$/d' file

Sample Output in the modified file

Hell
No hello stuff here
Unjulating stuff
Some sentence

What happens above

1. Using the ^ in the pattern we check for the beginning of the line.
2. We check the pattern Hello(number) : using Hello[[:digit:]]+ :$ . Note that I used -E to enable sed extended regular expressions so I need not escape the + ie ( \\+ ). Here [[:digit:]] is a class which contains all the decimal digits and + is used to check if the pattern before it matches at least one time.
3. Check the end of the line using $
4. For a matched pattern, delete it line using the d option
5. I have also used the sed inplace edit option -i so that the changes are directly saved to the file.

If you wish to change the a line the begins with Hello(number) : then use the below script

sed -Ei '/^Hello[[:digit:]]+ :/d' file

You might have notices that I just removed the $ , so our pattern matches any line that starts with Hello(number) :

Hope this helps.