Delete files permanently with shred command in Linux – Remove absolutely

terminal-logo-small

Sometimes need to delete files whose contents should disappear absolutely, completely and safely. Linux command rm just remove file and it is still possible to dig out from the disk. Fortunately for Linux can be found in shred program that removes the files permanently. Shred command is easy and quickly to use cases when files need to deleted forever.

Shred command usage

Create test file:

Delete file with shred command:

Output:

Options used:

CAUTION: Note that shred relies on a very important assumption: that the file system overwrites data in place. This is the traditional way to do things, but many modern file system designs do not satisfy this assumption. The following are examples of file systems on which shred is not effective, or is not guaranteed to be effective in all file system modes:

  • log-structured or journaled file systems, such as those supplied with AIX and Solaris (and JFS, ReiserFS, XFS, Ext3, etc.)
  • file systems that write redundant data and carry on even if some writes fail, such as RAID-based file systems
  • file systems that make snapshots, such as Network Appliance’s NFS server
  • file systems that cache in temporary locations, such as NFS version 3 clients
  • compressed file systems

In the case of ext3 file systems, the above disclaimer applies (and shred is thus of limited effectiveness) only in data=journal mode, which journals file data in addition to just metadata. In both the data=ordered (default) and data=writeback modes, shred works as usual. Ext3 journaling modes can be changed by adding the data=something option to the mount options for a particular file system in the /etc/fstab file, as documented in the mount man page (man mount).

More info about options with command:

Share this post

Submit a Comment

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code class="" title="" data-url=""> <del datetime=""> <em> <i> <q cite=""> <strike> <strong> <pre class="" title="" data-url=""> <span class="" title="" data-url="">