Troubleshooting with Ubuntu Live CD

Revision as of 16:49, 6 January 2010 by Christopher Hunt (talk | contribs) (CHMOD help)

If you look through the CD rack in the Walk-In you will find a few Ubuntu CDs. Put these in a computer of any model and boot from CD to start up a fully working system without installing anything to the hard drive.

When to use Ubuntu live CD


  • Test hardware: if sound / video / network works, you know that the hardware is not broken.
  • Retrieve / copy files from PC hard drives
  • Resize, create, delete partitions using the Partition Editor
  • Memory test option
  • Have a fully working OS with Office suite, browser, etc. without relying on the hard disk


  • Bart is a little slower to start and has less programs available.
  • Ubuntu is generally immune to viruses & spyware.
  • With Ubuntu you can use any of the preloaded programs while transferring files or doing other useful stuff.

Don't use when...

  • If you want an official hardware diagnosis on a Dell, use the Dell diagnostics instead.
  • Ubuntu doesn't have Norton Ghost for reimaging computers. If you want Ghost, use the Bart/Ghost CD.

Basic usage

Starting the live CD

  1. Insert CD into hard drive.
  2. Turn on or restart computer.
  3. Tell computer to boot from CD. (on Dell: press F12 at first screen)
  4. Choose the language and select "Try Ubuntu without installing". (Or, if you want to test the computer's memory, select "Test Memory". Ubuntu won't load if you test memory; it will just do a basic memory test and show you the results.)
  5. Wait for Ubuntu to boot to the desktop. If the sound is working, it should play a startup sound.

Navigating Ubuntu

  • Applications will be listed in categories under the "Applications" menu in the top left corner.
  • Connect to connected drives using the "Places" menu.
  • Access system settings and certain admin applications (like the Partition Editor) through the "System" menu.
  • Use the Network icon at the top-right to connect to wired or wireless networks. If plugged in, Ubuntu should connect to the wired network automatically.
  • The "Add/Remove Programs" application under the "Applications" menu won't install many programs on a live CD system; it's mainly to show you what programs are available once Ubuntu is installed on the computer.
  • External media are plug-and-play supported. When you plug in a USB drive, external hard drive, etc., an icon for it will appear on the desktop. It will also be accessible under the "Places" menu.
  • Use the "Places" menu in the upper left to access external media etc. on the computer. The file browser, Nautilus, will be intuitive to use for OSX and Windows users.
    (When using a live CD, the "Home", "Music", etc. folders are stored only temporarily in the RAM - don't make the mistake of saving important files here!)

How to access an uncooperative NTFS drive on Ubuntu using force-mounting

NTFS is the standard Windows filesystem type, designed by Microsoft and used in Windows 2000, XP, Vista, and 7. NTFS was designed without much cross-platform compatibility or open specifications in mind. As a result, historically it has been very hard to access NTFS drives using Linux, let alone write to them. Now Linux systems, including Ubuntu, can read and write perfectly to NTFS drives - with one exception.

NTFS drives have a switch that indicates whether they are currently in use (or "dirty"). When Windows shuts down normally, this switch is turned off as part of the shutdown process. However when Windows freezes or crashes or is shut down improperly, this switch is not set to "off". You can see this when you start Windows the next time - it tells you "Windows was not shut down properly" and offers to start up in Safe Mode.

When you try to access an NTFS drive on Ubuntu, Ubuntu will automatically mount the drive and display the contents with read/write access as long as the drive's in-use switch is not "dirty". Otherwise it will display a long error message explaining that it cannot mount the dirty NTFS drive.

  • (Need Screenshot)

If this happens, you can use 2 terminal commands to mount the drive. We do what's suggestively called a "forced mount". It's a little scary but not hard at all. Here's how:

  1. Keep the error message window open. Locate the part where it suggests the Terminal command that looks something like the following - your details may differ:
    mount -t ntfs-3g /dev/sdb1 /media/disk1 -o force
  2. Look closely at this command. It basically says: Do this action (mount/access drive) - (option -t) - Type of driver to use (drive is NTFS) - Place where the "raw" drive is found (in folder /dev) - Where to attach the drive to (in folder /media) - (More options -o) - Force mounting even if drive is "dirty". Get it?
  3. Open the Terminal program: Applications -> Accessories -> Terminal
  4. Create the folder name under /media as mentioned in the Terminal command suggested in your error window, using the command "sudo mkdir" (make a directory, and do it with Super privileges) - then press ENTER. For example, I would type:
    sudo mkdir /media/disk1
  5. If an error message came up, you probably typed it wrong. If no error message came up, you're ready to enter the command discussed in #1, which mounts the hard disk.
  6. Type the mentioned MOUNT command exactly as shown in the error window, then press ENTER. If you have followed all the instructions correctly, the Windows drive should appear on the Desktop. You can now access it and read and write files.

File permissions

Sometimes Ubuntu might balk at copying or overwriting a file, saying that you have "insufficient permissions". This could happen for multiple reasons:

  • The files to move are corrupted and can't be moved
  • The space where you're trying to move files is read-only (or the copy-to medium is corrupted and is perceived as being read-only)
  • You're trying to access files that are set to have very restrictive permissions (maybe on a Mac)
  • An Ubuntu system glitch

If the media is damaged or files are corrupted, you probably won't be able to move the files. However, often the problem isn't that severe, and changing permissions can make the files usable.

Check and adjust the permissions status on the file

It's often helpful to find out what the permissions are on the files you want to move, as well as on the directory you're trying to move them to.

  1. Right-click on a file and select Properties.
  2. In the Properties window, click on the Permissions tab.

The Permissions tab tells you what the file's permission levels are for the owner, a group, and others. If you are unable to modify the file, that's because the permissions are too restrictive for the group you are part of (often the "Others" group). Generally, you want at least "Read and write" access to be able to view, move, and modify files.

To change permissions on a file, we'll use Terminal.

  1. Open Terminal: Applications -> Accessories -> Terminal
  2. Use the cd (Change Directory) command to navigate to the location of the files whose permissions you want to change. For example, to navigate to the cdrom folder inside media, type in cd /media/cdrom.
    • You can Alt+Tab back to the file explorer to see the directory path.
    • Use the ls command to view the files inside your current directory.
  3. When you are in the right directory, use the chmod command to change the permissions of the file(s). Here are some examples:

chmod a+rw 30744.pdf - gives all groups read-write access to the file 30744.pdf
chmod -R a+rw * - gives all groups read-write access to all files and folders in the current directory, as well as sub-folders

For more cryptic help, type in chmod --help.

Check the permissions status on the directory

If the permissions on the file seem fine, you can also check the permissions on the destination directory. If you don't have write-access there, you won't be able to move or delete files there!

  1. Navigate so you can see the icon for the folder you want to copy to.
  2. Right-click on the folder icon and select Properties.
  3. In the Properties window, click on the Permissions tab.

If the permissions are read-only, often this is because Ubuntu can't communicate fully with the storage medium. Don't try to force-copy files here, as the medium might not be stable. Try removing and re-adding the storage device.

Using the Partition Editor

One of the many tools that comes default with the Ubuntu live CD is the Partition Editor - basically does the same job of Norton's $70 Partition Magic. You can use this to create, delete, move, resize, or reconfigure partitions on a hard drive. Partition Editor works with NTFS (Windows), FAT (old), and EXT (Linux) filesystems, plus others.

Find Partition Editor: System -> Administration -> Partition Editor