use command prompt ?

Console functions available through jtag_uart are for example:

printf(..) : print formatted string on the console pan

getc() : get input data from console

You can't transfer a file from your pc's hd to the Nios, if you mean this.

I know there's a way to transfer files but I don't know how to do it. Search the Altera website and forum and you'll probably find it.

If you really need the script.txt and this is constant, a simple way to do it is incorporate the file content into your code.