tell(Filename)
Open file for output.
Remarks
tell/1 opens the disk file FileName for writing and attaches the output stream to it. If a file called FileName already exists on the disk, tell/1 will erase its contents.
Example
tell("dd.txt"), write("line 1\n"), write("line 2\n"), write("line 3\n"), told, see("dd.txt"), readln(Str1), seen, display(Str1).