使用/删除文本文件中包含特定字符串的行

Question

I have a text file with dates in this format: 27/8/2019 I would like to remove all lines except for those that contain 27/8/2019

If I use sed, that would be:

sed -i '/pattern/!d' file.txt

The problem is that when I have a pattern with '/', I have the next error:

sed: -e expression #1, char 5: unknown command: `8'

Answer 1

转义斜线：

sed -i '/27\/8\/2019/!d' file.txt

Answer 2

Using awk

awk '/27\/8\/2019/' file.txt

If date is just a sample, use this to keep all date line:

awk '/[0-9]+\/[0-9]+\/[0-9]+/' file.txt

To update file inline with awk

awk '-your code-' file.txt > tmp && mv tmp file.txt