truncate - shrink or extend the size of a file to the specified size
To Clear contents of a file with truncate
$ truncate -s 0 example.txt
To truncate a file to a specific size
$ truncate -s 200K example.txt
To extend file size
$ truncate -s +400K example.txt
To reduce file size
$ truncate -s -100k example.txt
regards,
T.Dhanasekar