#!/usr/bin/env bash
# karm.sh
# A tiny secure deletion tool
# Uses dd, fsync and /dev/urandom to overwrite
# a file twice with a random data stream and delete it.
# @_ksaver, Feb 2010. 
# Licence: Public Domain Code.
# Use it with caution and under your own risk.
# Not warranty provided at all.
VERSION='0.4'

function karm(){
# Gets file name from $1
FILE="$1"

# Gets file size.
SIZE=$(/usr/bin/du -k "$FILE")
COUNT=${SIZE%"$FILE"*}	

# check if urandom exists
if [ -e '/dev/urandom' ]
then 
	RANDD='/dev/urandom'
else
	RANDD='/dev/random'
fi

# Send random stream to file...
/bin/dd if=$RANDD of="$FILE" bs=1k count=$COUNT &> /dev/null

# If data was successfuly written...
if [ $? = 0 ]
then
	# forces writing of cached file to physical storage...
	(/usr/bin/env fsync "$FILE" &> /dev/null && return 0) \
	|| ( sync && return 0)
else
	return 1
fi
}

function kdelete(){
# unlink the karmed file's inode...
/bin/rm "$1" > /dev/null || return 1
}

# _main_
# if not arguments were given...
if [ -z "$1" ]
then
	echo -e "\tkarm $VERSION: Secure deleting tool."
	echo -e "\tSyntaxis: $0  <File_to_delete>"
	exit 1
else
	FILE="$1"

	# If file exists
	if [ -f "$FILE" ]
	then
		echo -n "karming $FILE... "
		karm "$FILE" && karm "$FILE" && kdelete "$FILE"
		if [ $? = 0 ]
		then
			# this far, everything has gone ok...
			echo " [OK]"
			exit 0
		else
			# May be you are not the owner of file
			echo -e "[ERR]:\n$FILE not karmed. Are you the owner?"
			exit 1
		fi
	else
		# File doesn't exist...
		echo "[ERR] $0: Is $FILE a valid file?"
		exit 1
	fi
fi
# EOF

A tiny secure deletion tool...


Example:

$ karm.sh image1.jpg 

karming image1.jpg...  [OK]

$ karm.sh /etc/passwd

karming /etc/passwd... [ERR]:

/etc/passwd not karmed. Are you the owner?

karm.sh: A tiny secure deletion tool.

Bash