Run dolphin file manager as root

Some system files are visible in mac finder only when it opened with root privileges.

kdesu dolphin

Change Password Of dmg files

hdiutil chpass <dmg_file_name>

Secure Delete Deleted Files

Warning! It’s critically important that you include the freespace portion of that command. If you don’t, diskutil will happily start securely erasing the entire disk, instead of just the free space!

# diskutil list
diskutil secureErase freespace 1 /dev/disk3s4

Check how fast is your mac write data to its disk

time dd if=/dev/zero bs=1024k of=tstfile count=1024

Secure Delete Files / Folders

srm <file_name> 
srm -r <folder_name>