引用环境变量替换文字模版
最后更新于：2022-04-02 03:47:56
[TOC]
## 方式一: 使用 envsubst
```
> export username=idcpj
> cat a.bash
echo "pwd is ${PWD}"
echo "username is ${username}"
> cat a.bash| envsubst > b.bash
echo "pwd is /Users/idcpj/Downloads"
echo "username is idcpj"
```
## 方式二:纯原生
```
> export username=idcpj
> cat c.bash
cat > d.bash << EOF
echo "pwd is ${PWD}"
echo "username is ${username}"
EOF
> bash c.bash
> cat d.bash
echo "pwd is /Users/idcpj/Downloads"
echo "username is idcpj"
```
';