#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)href="\/([^"]*)"
Local $sString = "<html>" & @CRLF & _
" <head>" & @CRLF & _
" <title>Hello</title>" & @CRLF & _
" </head>" & @CRLF & _
" <body>" & @CRLF & _
" <p>this is a simple text in html file</p>" & @CRLF & _
" <a href="https://google.com">Google</a>" & @CRLF & _
" <a href="/frontend/login/">Login</a>" & @CRLF & _
" <a href="/something/work/">Something</a>" & @CRLF & _
" </body>" & @CRLF & _
" </html>"
Local $sSubst = "href="\/more\/\1additional"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm