Applied Mathematics Computer Users Guide

Linux

This section concerns itself with Linux in the department.

Why Scientific Linux?
But Debian/Mandrake/SuSE/etc is so much better.
What's this /yesterday directory?
What's this /scratch directory?
How do I change screen resolution?
How do I burn Linux ISOs on a Windows box?
How do I burn CDs on Linux?
Can I know the root password?

Why Scientific Linux?

Scientific Linux is a recompile of the open source code of Red Hat Enterprise. As such it is compatible with external packages such as IDL which are certified on RHEL, and our Dell hardware which is similarly certified for RHEL. The current version used in the department is 3.0.4

But Debian/Mandrake/SuSE/etc is so much better.

Maybe. However, they're not certified on the hardware and they're not certified for the software. Have fun sorting out all the drivers. 8-)

What's this /yesterday directory?

If you see a /yesterday directory, that means that every night in the wee small hours, the /home (or sometimes the whole / ) partition is synched onto /yesterday, which is on a separate hard drive. This gives you a self-rescue capability if you accidentally delete the wrong file(s). The sync includes deleting anything that is no longer in /home, so you can only self-rescue stuff the same day. Simply copy it back:

% rm /home/richard/veryimportantfile.ps
% cp /yesterday/home/richard/veryimportantfile.ps /home/richard

Of course, since the sync only happens once a day, you will also not be able to rescue anything you have created the same day and accidentally lost. Finally, don't write anything directly to the /yesterday directory. If you do, it will (surprise!) be deleted in the nightly sync if it doesn't appear in the same hierarchical position on the /home disk.

What's this /scratch directory?

A bit of file space that isn't backed up. Put what you want into it, but it is NOT BACKED UP.

How do I change screen resolution?

You can't. Ask me. All Linux boxes (from July 2005 onwards) will default to 1280 x 1024 resolution. If you want this changed, ask me.

How do I burn Linux ISOs on a Windows box?

Download the iso and rename it .raw. Get a copy of WinOnCD (preferably 3.7, which works). Start it up. Select Other, Track Image, click Disk. Select Close CD, Tracks cannot be added later and Disc/Session at Once and Write Immediately. Leave all other boxes blank/default. Drag the .raw file to the lower window and click Properties. Select file format 2048 - Mode 1 or Mode 2 Form 1 Data Only and track format CD-ROM Mode 1, click Disk and then Record.

How do I burn CDs on Linux?

Added 14/12/06: If you are using kernel version 2.6.9 or later (check the output of uname -a) then please see this answer in the OTRS FAQ.

First of all, check that

  # cdrecord -scanbus

returns a sensible pseudo-SCSI bus with the CD recorder sitting at something like

  0,0,0

For the purpose of this example we will assume it is sitting at 0,0,0.

Secondly, insert your CD-R. If a window pops up called burn::, kill it.

Now all you need to do is make your file system to burn, ensuring that it fits on the CD, of course...

  % mkisofs -l -v -o /tmp/filesystem.iso /home/user/stufftobackup

and test the burn:

  % cdrecord -dummy -v dev=0,0,0 /tmp/filesystem.iso

If that works, burn it:

  % cdrecord -v dev=0,0,0 /tmp/filesystem.iso

If the dummy run doesn't work, use the burnfree option:

  % cdrecord -v driveropts=burnfree dev=0,0,0 /tmp/filesystem.iso

As usual, RTFM; 'man mkisofs' and 'man cdrecord' will reveal a host of other possibilities.

We do not support CD-RW, DVD+/-R, or DVD+/-RW media in the department.

Can I know the root password?

By all means. However, you will then be totally responsible for your system. We cannot help with any problems. You will also not be permitted write access to anyone else's disk - including shared use areas.

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