Commands using shred (11)

  • securely erase unused blocks in a partition

    This command securely erases all the unused blocks on a partition. The unused blocks are the "free space" on the partition. Some of these blocks will contain data from previously deleted files. You might want to use this if you are given access to an old computer and you do not know its provenance. The command could be used while booted from a LiveCD to clear freespace space on old HD. On modern Linux LiveCDs, the "ntfs-3g" system provides ReadWrite access to NTFS partitions thus enabling this method to also be used on Wind'ohs drives. NB depending on the size of the partition, this command could take a while to complete. Show Sample Output


    8
    # cd $partition; dd if=/dev/zero of=ShredUnusedBlocks bs=512M; shred -vzu ShredUnusedBlocks
    mpb · 2009-06-21 14:17:22 12
  • How to secure delete a file

    Instead, install apt-get install secure-delete and you can use: -- srm to delete file and directory on hard disk -- smem to delete file in RAM -- sfill to delete "free space" on hard disk -- sswap to delete all data from swap


    6
    shred -u -z -n 17 rubricasegreta.txt
    0disse0 · 2010-01-31 15:24:54 7
  • Erase to factory a pendrive, disk or memory card, and watch the progress


    6
    sudo shred -vz -n 0 /dev/sdb
    bugmenot · 2012-08-06 22:37:44 6
  • Securely destroy data (including whole hard disks)

    GNU shred is provided by the coreutils package on most Linux distribution (meaning, you probably have it installed already), and is capable of wiping a device to DoD standards. You can give shred any file to destroy, be it your shell history or a block device file (/dev/hdX, for IDE hard drive X, for example). Shred will overwrite the target 25 times by default, but 3 is enough to prevent most recovery, and 7 passes is enough for the US Department of Defense. Use the -n flag to specify the number of passes, and man shred for even more secure erasing fun. Note that shredding your shell history may not be terribly effective on devices with journaling filesystems, RAID copies or snapshot copies, but if you're wiping a single disk, none of that is a concern. Also, it takes quite a while :)


    5
    shred targetfile
    sud0er · 2009-04-28 19:57:43 9
  • Safe Delete

    remove file that has sensitive info safely. Overwrites it 33 times with zeros


    2
    shred -n33 -zx file; rm file
    copremesis · 2009-05-08 19:15:41 8
  • Realy remove file from your drive

    This command remove a file from your filesystem like the normal rm command but instead of deleting only the inode information this also delete the data that was stored on blocks /!\ warning this may be long for large files Show Sample Output


    1
    function rrm(){ for i in $*; do; if [ -f $i ]; then; echo "rrm - Processing $i"; shred --force --remove --zero --verbose $i; else; echo "Can't process $i"; type=$(stat "$1" -c %F); echo "File $i is $type"; fi; done;}
    thelan · 2010-06-10 22:40:27 8
  • securely overwrite a file with random junk, rename it to clear the directory entry and finally delete it

    Show Sample Output


    0
    shred -vzu /tmp/junk-file-to-be-shredded
    mpb · 2009-06-18 12:00:19 11
  • Destroy file contents after encryption

    Make sure the file contents can't be retrieved if anyone gets ahold of your physical hard drive. With hard drive partition: gpg --default-recipient-self -o /path/to/encrypted_backup.gpg -e /dev/sdb1 && shred -z /dev/sdb1 WARNING/disclaimer: Be sure you... F&%k it--just don't try this.


    0
    gpg -e --default-recipient-self <SENSITIVE_FILE> && shred -zu "$_"
    h3xx · 2011-07-24 05:51:47 4
  • Completly blank a disk

    Instead of zeroing the filesystem, this command overwrites N times (default is 3) the disk content, making data recovery much harder. The command accepts many more options


    0
    shred --iterations=N /dev/sdaX
    bibe · 2012-01-23 20:40:36 9
  • Shred an complete disk, by overwritting its content 10 times

    Shred can be used to shred a given partition or an complete disk. This should insure that not data is left on your disk


    -2
    sudo shred -zn10 /dev/sda
    dcabanis · 2009-04-30 13:02:43 8
  • Delete a file securely by overwriting its contents


    -5
    shred -v filename
    techie · 2013-05-07 14:58:17 7

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list block devices
Shows all block devices in a tree with descruptions of what they are.

Show all detected mountable Drives/Partitions/BlockDevices
Yields entries in the form of "/dev/hda1" etc. Use this if you are on a new system and don't know how the storage hardware (ide, sata, scsi, usb - with ever changing descriptors) is connected and which partitions are available. Far better than using "fdisk -l" on guessed device descriptors.

Create QR codes from a URL.
QR codes are those funny square 2d bar codes that everyone seems to be pointing their smart phones at. Try the following... $ qrurl http://xkcd.com Then open qr.*.png in your favorite image viewer. Point your the bar code reader on your smart phone at the code, and you'll shortly be reading xkcd on your phone. URLs are not the only thing that can be encoded by QR codes... short texts (to around 2K) can be encoded this way, although this function doesn't do any URL encoding, so unless you want to do that by hand it won't be useful for that.

list files recursively by size

List all execs in $PATH, usefull for grepping the resulting list
##Dependancies: bash coreutils Many executables in $PATH have the keyword somewhere other than the beginning in their file names. The command is useful for exploring the executables in $PATH like this. $ find ${PATH//:/ } -executable -type f -printf "%f\n" |grep admin lpadmin time-admin network-admin svnadmin users-admin django-admin shares-admin services-admin

Rename files in batch

Show what PID is listening on port 80 on Linux

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Extract audio from a video
With the -vn switch we make our intentions clear and ask FFmpeg not to bother itself with the video. Next we specify the audio codec copy, which tells FFmpeg to use the same codec to encode the audio, which it uses to decode it. To keep things simple, we'll just keep the sampling and bitrate values the same.

Convert flv without re-encoding

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