System Task Utilities

Note

This documentation is extracted from the System Rescue CD documentation found on line at http://www.sysresccd.org/Online-Manual-EN. Please refer to the original documentation there.

Back up the partition table

sfdisk is a tiny program which saves the partition table to a regular file and only takes a few seconds. As an initial step for system recovery before making things worse, backup the system table now! For example:

sfdisk -d /dev/sda > sda.110601.2345.partTable

Copy the backup to another hard disk, removable media (thumb disk, floppy or CD) or ftp it to another computer. To Restore a backed up system table, first back up the current partition table, even if it seems to be damaged. This will allow you to undo the restoration. Then use the command:

cat sda.110601.2345.partTable | sfdisk /dev/sda

Warning

This command is very dangerous, because it overwrites the existing partition table.

Back up partition contents

Partimage (client and server) are provided, which will save an existing partition into an image file. If something goes wrong, you can restore the partition from the image. A semi-text interface is provided, and this should not be very hard to use. You need a partition with a lot of free space to store the image file.

Two versions of partimage are provided: one for local use, and one for remote administration. The local version is compiled without SSL and without login support. The client is available by typing partimage, and the server with partimaged. You should use this client in most cases, and when you want to connect to a partimaged server that does not support SSL.

The secured version is compiled with SSL and login support. The client is available by typing partimagessl, and the server with partimagedssl. You should use this client when you connect to a partimaged server that expects an SSL encrypted connection with login.

Archiving

SystemRescueCd comes with a lot of archive programs. You can use zip/unzip for the ZIP format, and rar/unrar for the RAR format. Even the new 7zip is supported with the p7zip command.

dar is an archiver similar to tar, but it is more powerful. Even when using compression, dar does not have to read the whole backup to extract one file. This way, if you just want to restore one file from a huge backup, the process will be much faster than using tar. Dar first reads the catalogue (i.e. the contents of the backup), then it goes directly to the location of the saved file(s) which you want to restore and then proceeds to restoration. In particular using slices, dar will ask only for the slice(s) containing the file(s) to restore. But you can also restore all files from an archive, dar will then read sequentially without seeking into the file. Except for the first and last slice, dar will not ask twice for the same slice.

Clam AntiVirus

Clam AntiVirus is a free anti-virus software which provides several important commands:

freshclam: This command updates the virus definitions. Of course, you need to be connected to internet for updating.

clamscan: This utility scans all the files in the named directory and searches for viruses.

Before scanning for viruses, you have to update the virus definitions. Because this is run from a CD-ROM, you may have read-only related problems. That is why you have to specify a read-write directory for definitions. Here is how to update definitions and make a scan:

1. ensure that you are connected to the internet.

2. Download the latest virus definitions by running the following commands:

   chown clamav:clamav /var/lib/clamav
   chown clamav:clamav /var/lib/clamav/*
   freshclam
   

3. Mount the partition to be scanned:

   mkdir -p /mnt/testpart
   mount /dev/sda1 /mnt/testpart
   

4. Perform the scan on the files:

   clamscan -r /mnt/testpart
   

If you really don’t have an internet connection, you can scan for viruses without updating the virus definitions. Of course, it’s less safe because only the older viruses can be detected.

Graphical Partition Tools

gparted a Partition-Magic clone which is easy to use and very powerful. This tool requires the X.Org graphical environment, so refer to the boot process if you do not know how to work in X.Org. You can run GParted by typing this command: gparted, or from the contextual menu on the desktop.

Accessing NTFS Partitions

NTFS (New Technology File System) is a very powerful file system provided with NT versions of Windows (Windows-NT, Windows-2000, Windows-XP). If you want full read-write support for NTFS disks, use Ntfs-3g (Ntfs third generation driver), which is a userspace program. With clamav and Ntfs-3g, you can check and repair viruses on a MS-Windows system without running Windows.

Read only support

To get read support only on an NTFS disk, mount it with the following command (replace xxx with the device name of your disk):

mount -t ntfs /dev/xxx /mnt/windows -o ro

This read-only support is safe (you cannot alter or damage your data). Use this if, for example, you just want to backup several files, or read a document.

Full Read-Write support

Use ntfs-3g for complete NTFS Write support with the command:

ntfs-3g /dev/sda1 /mnt/windows

In this example, we suppose the device name of the NTFS partition is /dev/sda1 and the mount point is /mnt/windows. If you do not know the device name, you may list partitions with cat /proc/partitions or use GParted.