首页 / UNIX / shred_linux_unix
shred_linux_unix
内容导读
互联网集市收集整理的这篇技术教程文章主要介绍了shred_linux_unix,小编现在分享给大家,供广大互联网技能从业者学习和参考。文章包含3365字,纯文字阅读大概需要5分钟。
内容图文
![shred_linux_unix](/upload/InfoBanner/zyjiaocheng/1301/a6562ea11fd24021be95815d9c2dde7e.jpg)
Sometimes you need to destroy or wipe data from hard drives (for example, before you sell your old hard drives on eBay) so that nobody else can access them. Simply deleting data (e.g. with rm) is not enough because that just removes the file system pointer, but not the data, so it can easily be undeleted with recovery software. Even zero‘ing out your hard drive might not be enough. Here‘s where shred comes into play - shred can overwrite the files and partitions repeatedly, in order to make it harder for even very expensive hardware probing to recover the data.
I do not issue any guarantee that this will work for you!
1 Preliminary Note
shred can be used to wipe files and also partitions and hard drives. If you take a look at shred‘s man page...
man shred
... you might notice the following:
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).
This is something you need to worry about only if you use shred to wipe files. However, as I want to wipe hard drives, I will use shred for whole partitions or hard drives in this tutorial.
2 Using shred
If you want to wipe your system partition, you must boot into a live system (such as Knoppix, the Ubuntu Live-CD, your hoster‘s rescue system, etc.). This is not needed if you don‘t want to wipe your system partition.
shred should already be installed (you can check with
which shred
); if it isn‘t you can install it as follows (Debian/Ubuntu/Knoppix):
apt-get install coreutils
As I said before, I want to use shred on partitions and hard drives. So, for example, to wipe the partition /dev/sda5, you can use
shred -vfz -n 10 /dev/sda5
-v: show progress
-f: change permissions to allow writing if necessary
-z: add a final overwrite with zeros to hide shredding
-n: overwrite N times instead of the default (3)
So this would overwrite /dev/sda5 ten times.
You can also use shred for RAID partitions, e.g.
shred -vfz -n 10 /dev/md1
And to wipe a full hard drive like /dev/sda, you can use
shred -vfz -n 10 /dev/sda
Please note that shred can take a long time, depending on the size of your partitions/hard drives and the number of runs (-n).
原文:http://www.cnblogs.com/jackydalong/p/4823233.html
内容总结
以上是互联网集市为您收集整理的shred_linux_unix全部内容,希望文章能够帮你解决shred_linux_unix所遇到的程序开发问题。 如果觉得互联网集市技术教程内容还不错,欢迎将互联网集市网站推荐给程序员好友。
内容备注
版权声明:本文内容由互联网用户自发贡献,该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容, 请发送邮件至 gblab@vip.qq.com 举报,一经查实,本站将立刻删除。
内容手机端
扫描二维码推送至手机访问。