BcWipe is an utility made by Jetico who uses military-grade procedures to surgically remove all traces of any file. It can be also used to wipe out securely the free disk space, using several secure methods.
BcWipe can be used free of charge and it's available for UNIX based systems.
This will clean the free disk space (-F) with just one pass (-m1). Different wipping schemes are:
-mb German BCI/VISTR 7-pass wiping -md U.S. DoD 5220-22M 7-pass extended character rotation wiping -me U.S. DoE 3-pass wiping -mg (default) 35-pass wiping by Peter Gutmann -ms 7-pass wiping by Bruce Schneier -mt 1-pass test mode: fill the start of 512-byte block with block number -mz 1-pass zero wiping -m N U.S. DoD 5220-22M N-pass extended character rotation wiping
bcwipe -vF -m1 /home/
Just use -r (for recursive deletion).
bcwipe -vr /tmp/folder_to_be_deleted