erase the content of a file

[karimtarbali]

hi
is there any way to erase the content of a file directly?
i use this commands :
set d [open Data/start.txt w]; puts $d " " ; close $d;

since i already has opened this file as append format (set d [open Data/start.txt w]) an error occurs in NEEshub interpreter.

is there any other way to erase the content of a file?

thanks for your help