need help with shell copy script

Hello, I have the following line of code to copy files. How do I make this overwrite a existing file?

do shell script copy & " " & posixfilePathFrom & " " & posixfilePathTo


I doubt that your code works at all
The shell command cp copies a file and overwrites an existing one

do shell script "/bin/cp " & posixfilePathFrom & space & posixfilePathTo