for example, I have a string variable that reads:

AAA=<?=\${AAA}=?>
BBB=<?=\${BBB}=?>
<%=[ "\${Alias}" == "" ]=%>
CCC=\${CCC}

I want to implement regular substitution, generating the string as

AAA=<?=${AAA}=?>
BBB=<?=${BBB}=?>
<%= [ "${Alias}" == "" ] =%>
CCC=\${CCC}

or

AAA=${AAA}
BBB=${BBB}
[ "${Alias}" == "" ]
CCC=\${CCC}

how to achieve it? I tried sed, etc., but the ability of Shell is limited, so it is difficult to achieve the effect.

Note: I want to achieve the effect of template engine replacement.