bash 如何从文件中删除包含特定字符串的行？
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How to remove line containing a specific string from file?
提问by Jared Aaron Loo
I have a file BookDB.txt which stores information in the following manner :
我有一个 BookDB.txt 文件，它以以下方式存储信息：
C++ for dummies:Jared:10.67:4:5
Java for dummies:David:10.45:3:6
PHP for dummies:Sarah:10.47:2:7
Assuming that during runtime, the scipt asks the user for the title he wants to delete. This is then stored in the TITLE variable. How do I then delete the line containing the string in question? I've tried the following command but to no avail :
假设在运行时，scipt 询问用户他想要删除的标题。然后将其存储在 TITLE 变量中。然后如何删除包含相关字符串的行？我尝试了以下命令但无济于事：
sed '/$TITLE/' BookDB.txt >> /dev/null
回答by fedorqui 'SO stop harming'
You can for example do:
例如，您可以执行以下操作：
$ title="C++ for dummies"
$ sed -i "/$title/d" a
$ cat a
**Java for dummies**:David:10.45:3:6
**PHP for dummies**:Sarah:10.47:2:7
Note few things:
注意几点：
- Double quotes in sed are needed to have you variable expanded. Otherwise, it will look for the fixed string "$title".
- With
-iyou make in-place replacement, so that your file gets updated once sed has performed. dis the way to indicatesedthat you want to delete such matching line.
- 需要在 sed 中使用双引号来扩展变量。否则，它将查找固定字符串“$title”。
- 随着
-i您进行就地替换，一旦 sed 执行，您的文件就会更新。 d是指示sed您要删除此类匹配行的方式。
回答by Avinash Raj
Your command should be,
你的命令应该是，
sed "/$TITLE/d" file
To save the changes, you need to add -iinline edit parameter.
要保存更改，您需要添加-i内联编辑参数。
sed -i "/$TITLE/d" file
For variable expansion in sed, you need to put the code inside double quotes.
对于 sed 中的变量扩展，您需要将代码放在双引号内。
