Cleandisk : a utility to wipe unused disk space

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Date:         Wed, 14 Sep 2005 12:59:44 -0700
To: aix-l@Princeton.EDU

##############################################
Havent used but located script to wipedisk
################################################
#!/bin/bash
#
# Cleandisk : a utility to wipe unused disk space
#
# Version 0.1
# Author : Iain Roberts
# Date : 25th October 2003
#

# This is a little shell script to wipe disk space
which is unused but may
# still have scraps of deleted files. It is designed
to be run on a running
# system. It does a number of overwrites specified
when the script is run.
# Each overwrite uses dd and writes first from
/dev/zero and then from
# /dev/urandom.

# The problem with this approach in a shell script is
that I can't see how to
# overwrite all unused disk space without risking
filling up the whole
# partition and so potentially causing problems on the
system. The way I've
# done it is to write the random/zero data to files.
As the available space
# gets smaller, the files get smaller to fill up more
of it. The script
# won't let the space run out completely, though,
which means that there
# will always be a small amount of disk space which
never gets overwritten.

# Oh - and it's damn slow too.

# This script is provided with absolutely no warranty,
nor any guarantee that
# it won't wreck your system. Use it with care.

#------------#
# Variables #
#------------#

FS=$1
typeset -i OVERWRITES=$2
typeset -i CHUNKS=0
typeset -i CSIZE=0

#------------#
# Functions #
#------------#

cleanup() {
       echo "Cleaning up files created by cleandisk."
       echo "Now deleting files $FS/cleandisk/*"
       /bin/rm -r $FS/cleandisk
}

msgcat() {
MSG[0]="Cleandisk completed. Only $FSFREE KB free
space was left in $FS"
MSG[1]="$FS/cleandisk already exists...exiting"
MSG[2]="You must specify a number of overwrites. I
recommend between 1 and 10"
MSG[3]="dd if=/dev/zero has failed. Please
investigate."
MSG[4]="dd if=/dev/urandom has failed. Please
investigate."
MSG[5]="$FS is not a partition mount point."
MSG[6]="Usage : cleandisk <mount_point>
<overwrite_count>. e.g. cleandisk /home 3"
MSG[7]="$FS/cleandisk exists. Please delete and try
again."

echo "${MSG[$1]}"
exit $1
}

#-----------#
# Main body #
#-----------#

[[ $OVERWRITES -lt 1 ]] && msgcat 2

if df $FS|awk '{print $6}' |grep -q "^${FS}$"
  then
    typeset -i FSFREE=$(df -k $FS|grep " $FS$"|awk
'{print $4}')

    # You might have a directory called cleandisk with
important files in
    # so, to be safe, I'll exit if you've got a
cleandisk directory.
    # Just manually delete the directory and re-run
script.
    if [ -e $FS/cleandisk ]
      then
        msgcat 7
      else
        echo "Creating directory $FS/cleandisk"
        mkdir $FS/cleandisk
    fi

    # This while loop runs once for each chunk
    while [ $FSFREE -gt 2048 ]
      do
        echo " $FSFREE KB left in $FS to wipe clean"

        # Figure out best chunk size (1MB/10MB/100MB)
        # Always leave > 2xchunk size free (e.g. if
chunk size is 10MB, at least
        # 20MB must exist to be wiped, so after wipe
at least 10MB will be free
        # This helps protect against filesystems filling up
from other
        # processes

        if [ $FSFREE -gt 204800 ]
          then
                  CSIZE=10240 # 100MB
         elif [ $FSFREE -gt 20480 ]
          then
                  CSIZE=1024 # 10MB
         elif [ $FSFREE -gt 2048 ]
          then
                  CSIZE=102 # 1MB(ish)
         else
                 cleanup
                 msgcat 0
         fi

        typeset -i MB=CSIZE/102
        typeset -i COUNT=0

        echo " Now writing a chunk of $MB MB (may
take some time)"
        printf " Overwrite count --> "

        # This while loop runs once for each overwrite per
chunk
        while [ $COUNT -lt $OVERWRITES ]
          do
           ((COUNT+=1))
            dd if=/dev/zero of=$FS/cleandisk/$CHUNKS bs=10240
count=$CSIZE >/dev/null 2>&1|| msgcat 3
            dd if=/dev/urandom of=$FS/cleandisk/$CHUNKS
bs=10240 count=$CSIZE >/dev/null 2>&1|| msgcat 4
           printf "$COUNT"
          done
        # End of loop running once per overwrite per
chunk

        FSFREE=$(df -k $FS|grep " $FS$"|awk '{print
$4}')
        ((CHUNKS+=1))
        echo -e "\n$CHUNKS chunk(s) have now been written."
       done
       # End of loop running once per chunk

    else
     msgcat 5
fi
           
cleanup
msgcat 0

Robert Lee Binkley leebinkley@yahoo.com
 IBM AIX Specialist Certified
 HP-UX System Administration Certified
Work It's Nice To Be Important But It's More Important To Be Nice

• Previous message: Shawn Bierman: "Re: Problem witj LPP file"
• Next in thread: Yves Dorfsman: "Re: Cleandisk : a utility to wipe unused disk space"
• Reply: Yves Dorfsman: "Re: Cleandisk : a utility to wipe unused disk space"
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