仅当文件不存在时才向文件追加一行 [英] Appending a line to a file only if it does not already exist

问题描述

我需要将以下行添加到配置文件的末尾:

I need to add the following line to the end of a config file:

include "/configs/projectname.conf"

到一个名为 lighttpd.conf

我正在考虑使用 sed 来执行此操作，但我不知道如何操作.

I am looking into using sed to do this, but I can't work out how.

如果该行不存在，我将如何仅插入它?

How would I only insert it if the line doesn't already exist?

推荐答案

保持简单:)

grep + echo 应该足够了:

grep -qxF 'include "/configs/projectname.conf"' foo.bar || echo 'include "/configs/projectname.conf"' >> foo.bar

• -q安静
• -x 匹配整行
• -F 模式是一个普通的字符串
• https://linux.die.net/man/1/grep
• -q be quiet
• -x match the whole line
• -F pattern is a plain string
• https://linux.die.net/man/1/grep

合并了@cerin 和@thijs-wouters 的建议.

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