<touch file="myfile"/>creates myfile if it doesn't exist and changes the modification time to the current time.
<touch file="myfile" datetime="06/28/2000 2:02 pm"/>creates myfile if it doesn't exist and changes the modification time to Jun, 28 2000 2:02 pm (14:02 for those used to 24 hour times).
<touch datetime="09/10/1974 4:30 pm"> <fileset dir="src_dir"/> </touch>changes the modification time to Oct, 09 1974 4:30 pm of all files and directories found in src_dir.