如何在文本文件中扩展Shell变量? [英] How to expand shell variables in a text file?

问题描述

考虑一个ASCII文本文件(可以说它包含非shell脚本语言的代码):

Consider a ASCII text file (lets say it contains code of a non-shell scripting language):

Text_File.msh:

spool on to '$LOG_FILE_PATH/logfile.log';
login 'username' 'password';
....

现在，如果这是一个Shell脚本，我可以将其作为$ sh Text_File.msh运行，并且Shell会自动扩展变量. 我想做的是让Shell扩展这些变量，然后按如下方式创建一个新文件，如Text_File_expanded.msh所示:

Now if this were a shell script I could run it as $ sh Text_File.msh and the shell would automatically expand the variables. What I want to do is have shell expand these variables and then create a new file as Text_File_expanded.msh as follows:

Text_File_expanded.msh:

spool on to '/expanded/path/of/the/log/file/../logfile.log';
login 'username' 'password';
....

---

考虑:

---

Consider:

$ a=123
$ echo "$a"
123

因此从技术上讲，这应该可以解决问题:

So technically this should do the trick:

$ echo "`cat Text_File.msh`" > Text_File_expanded.msh

...但是它不能按预期工作，并且输出文件与源文件相同.

...but it doesn't work as expected and the output-file while is identical to the source.

因此，我不确定如何实现此目标..我的目标是使维护非shell脚本中嵌入的目录路径更加容易. 这些脚本不能包含任何UNIX代码，因为它不是UNIX shell编译的.

So I am unsure how to achieve this.. My goal is make it easier to maintain the directory paths embedded within my non-shell scripts. These scripts cannot contain any UNIX code as it is not compiled by the UNIX shell.

推荐答案

此解决方案虽然不美观，但可以使用.创建脚本调用shell_expansion.sh:

This solution is not elegant, but it works. Create a script call shell_expansion.sh:

echo 'cat <<END_OF_TEXT' >  temp.sh
cat "$1"                 >> temp.sh
echo 'END_OF_TEXT'       >> temp.sh
bash temp.sh >> "$2"
rm temp.sh

然后您可以按以下方式调用此脚本:

You can then invoke this script as followed:

bash shell_expansion.sh Text_File.msh Text_File_expanded.msh

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