I have the file ~/nginx_app containing this conf template:
server {
root /var/www/html/${domain}/;
server_name ${domain} www.${domain};
}
我也有这个脚本：
#!/bin/bash
domain="$1" && test -z ${domain} && return
cat ~/myAddons/nginx_app > /etc/sites-available/${domain}.conf
As you can see, I desire to redirect the content of nginx_app into ${domain}.conf, which the script creates based on the template.
Now, need the variables inside the template to be expanded, when their cat redirection takes place. How would you promise that expansion does indeed take place?
我在想这里字符串，但我知道它会打印一个字符串：
cat > "etc/nginx/sites-available/${domain}.conf" <<< "source ~/myAddons/nginx_app"
还有这个
cat ~/myAddons/nginx_app > etc/nginx/sites-available/${domain}.conf
更新资料
After running the script, the end state should /etc/sites-available/example.com.conf:
server {
root /var/www/html/example.com/;
server_name example.com www.example.com;
}
我得到的工作（根据StephenHarris评论编辑）是：
The second
$domainof the sed command expands intoaain my test case. However, since the first$domainhas its$identifier escaped, it is NOT expanded.There exists another command-line program called
awkwhich has a more powerful way of passing variables from outside it to inside it, butsedis considered faster and more efficient (not sure if really true nowadays), so that's why I answered withsedbecause this was a simple case. Inawk, you could use:Here, the
-voption toawkdefines anawkvariable, andgsubis anawkfunction for performing a global substitution for a given line. The escapinng sequence\\is slightly longer than for thesedsolution.您想要做的基本上是字符串替换，以处理输入文件的内容，而不是变量扩展（尽管在引用变量时确实由Shell执行，但这不是输入内容的工作）。
That can be done with
sed, and shell variable there can be used, although consult this answer for possible issues.Adjust
inputandoutputaccordingly. Note also that I use$1positional parameter directly, instead of copying that to variable.如果可以的话，最好的方法是有一个充当模板的脚本，并且您只能将变量作为位置参数提供给脚本命令行，或者通过提供变量文件来提供。复制文件并通过替换字符串来执行杂技并不是最好的方法，尤其是当模式变得复杂时。