Use FileTruncate utility to truncate content of an existing file to 0 bytes without deleting the file. This can be used if a file is in use, but still writable.
Download FileTruncate.exe (16 KB).
Here is the help screen containing complete description and example
Usage: FileTruncate file_name
Command line parameters:
|file_name -||Name of the file that will be emptied.|
Run FileTruncate.exe without parameters from the DOS command prompt to see full
description of the supported parameters.
For example, FileTruncate myfile.txt will empty myfile.txt.