如何用文本文件中的命令输出替换值? [英] How to replace a value with the output of a command in a text file?

问题描述

我有一个文件，其中包含:

I have a file that contains:

<?php return 0;

我想用当前时间戳替换bash值0.

I want to replace in bash, the value 0 by the current timestamp.

我知道我可以通过以下方式获取当前时间戳:

I know I can get the current timestamp with:

date +%s

我可以用sed替换字符串:

sed 's/old/new/g' input.txt > output.txt

但是如何结合两者来实现我想要的呢?只要不使用sed和date的解决方案，只要它们仅使用Shell工具，也将受到欢迎.

But how to combine the two to achieve what I want? Solutions not involving sed and date are welcome as well, as long as they only use shell tools.

推荐答案

通常，请使用以下语法:

In general, do use this syntax:

sed "s/<expression>/$(command)/" file

这将查找<expression>，并将其替换为command的输出.

This will look for <expression> and replace it with the output of command.

对于您的特定问题，可以使用以下内容:

For your specific problem, you can use the following:

sed "s/0/$(date +%s)/g" input.txt > output.txt

这将用命令date +%s的输出替换文件中存在的任何0.请注意，您需要使用双引号使$()中的命令得到解释.否则，您将得到文字$(date +%s).

This replaces any 0 present in the file with the output of the command date +%s. Note you need to use double quotes to make the command in $() be interpreted. Otherwise, you would get a literal $(date +%s).

如果要自动更新文件，请将-i添加到sed命令:sed -i "s/....这称为就地编辑.

If you want the file to be updated automatically, add -i to the sed command: sed -i "s/.... This is called in-place editing.

提供具有以下内容的文件:

Given a file with this content:

<?php return 0;

让我们看看它返回什么:

Let's see what it returns:

$ sed "s/0/$(date +%s)/g" file
<?php return 1372175125;

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