在属性文件中替换环境变量 [英] Replacing environment variables in a properties file

问题描述

在Linux中，说我有以下文件(例如conf.properties):

In Linux, say I have the following file (e.g. conf.properties):

HOST_URL=http://$HOSTNAME
STD_CONFIG=http://$HOSTNAME/config
USER_CONFIG=http://$HOSTNAME/config/$unconfigured

我想创建一个替换了所有环境变量的文件...假设环境变量$ HOSTNAME为'myhost'并且未设置$ unconfigured，脚本应产生以下输出:

I want to create another file with all the environment variables replaced...e.g. say the environment variable $HOSTNAME is 'myhost' and $unconfigured is not set, a script should produce the following output:

HOST_URL=http://myhost
STD_CONFIG=http://myhost/config
USER_CONFIG=http://myhost/config/

我本以为可以用一种简单的单线形式，使用某种sed/awk魔术来完成此操作，但是我不是专家，我的搜索也很普遍，因此，感谢您的帮助.

I was thinking this could be done in a simple one-liner with some sort of sed/awk magic, but I'm no expert and my searches have been in vein, so appreciate any help.

我应该提到该文件实际上可以是任何格式的文本文件，例如xml.我只想用环境中当前设置的值替换任何看起来像env变量的值.

I should mention that the file can really be any format text file, for example xml. I just want to replace anything that looks like an env variable with whatever is currently set in the environment.

推荐答案

sed 's/$HOSTNAME/myhost/g;s/$unconfigured//g' yourfile.txt > another_file.txt

更新:

根据您问题中的更新，这将不是一个好的解决方案.

update:

Based on updates in your question, this won't be a good solution.

这基于

This is based on an answer to a related question. I've hacked at it (I'm unfamiliar with perl) to remove undefined vars.

perl -p -e 's/\$\{([^}]+)\}/defined $ENV{$1} ? $ENV{$1} : $&/eg; s/\$\{([^}]+)\}//eg' yourfile.txt

应适用于任何输入文本文件，但是您将需要使用${...}格式定义vars，该格式可简化字符串匹配.

Should work for any input text file, however you will need to define vars using the ${...} format which simplifies the string matching.

(关于eval邪恶的言论转移到

(rant regarding the evilness of eval moved to a separate post so as not to confuse readers)

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