>> fd.write('0') [cut] > > f = file('large_file.bin','wb') > f.seek(409600000-1) > f.write('\x00')
While a mindblowingly simple/elegant/fast solution (kudos!), the OP's file ends up with full of the character zero (ASCII 0x30), while your solution ends up full of the NUL character (ASCII 0x00): [EMAIL PROTECTED]:~/temp$ xxd op.bin 0000000: 3030 3030 3030 3030 3030 0000000000 [EMAIL PROTECTED]:~/temp$ xxd new.bin 0000000: 0000 0000 0000 0000 0000 .......... (using only length 10 instead of 400 megs to save time and disk space...) -tkc -- http://mail.python.org/mailman/listinfo/python-list