05.16.2005 18:11

Old Accounts Purged

I've just purged the system of accounts that were marked as expired as of 2004. The purge has gained us about 14 GB of space on the /home/students partition, and bits and pieces elsewhere.

If, by chance, I accidentally deleted an account that should still exist, please let me know as soon as possible. I can still restore such accounts from our disk or tape backups.

Faculty folks: If you end up working with a student whose account has been removed, we have a tape archive of the older accounts, so we can restore their contents if need be. There will be a delay, however, as I plan to store that tape in another physical location.

Posted by C.M. Connelly | Permalink | Categories: System Maintenance, Linux

05.05.2005 18:07

Stupid MATLAB Tricks

There's been a problem with the open file dialog in MATLAB ever since we upgraded to MATLAB 7. The problem manifests itself as follows: you click on File->Open from the menu bar or you click on the open icon on the tool bar. You get a file picker dialog. You move to the directory where your .mat file lives, then click it to select it and click open or simply double-click the file name. One of two things then happens: You get a dialog telling you ``File not Found'' or you get an error message similar to

at javax.swing.filechooser.FileSystemView.getFiles(Unknown Source)
at javax.swing.plaf.basic.BasicDirectoryModel$LoadFilesThread.run(Unknown Source)

It turns out that this problem is somehow triggered by the LANG environment variable (it looks like something to do with Unicode). There are a couple of workarounds:

  1. Type the full filename and path in the dialog
  2. Use the load or edit commands in the MATLAB Command Windows
  3. Navigate to your working directory (either before you start MATLAB, with cd in your terminal window or with the navigation buttons in the MATLAB Current Directory browser pane) and open files from the Current Directory browser
  4. Unset the LANG environment variable before starting MATLAB

I have replaced the link to the latest MATLAB binary in /shared/local/bin with a small script that unsets the LANG environment variable and then starts MATLAB. The change should be transparent to end users, but it should be possible to open files directly from the open file dialog with this change.

Note that if you start MATLAB in any way other than using the matlab in /shared/local/bin, this change won't help you. You can check to see what your shell thinks it should run when you type matlab by typing the following:

linux% which matlab

You should see


If you don't, you can get the same effect by typing something similar to

For csh variants:

linux% ( unsetenv LANG ; /path/to/my/matlab ) &

For Bourne-shell variants:

linux$ ( unset LANG ; /path/to/my/matlab ) &

Posted by C.M. Connelly | Permalink | Categories: System Maintenance, Linux

05.05.2005 12:23

Server Burps

Last night around 5:30 we had some issue with the department's main server. They originally manifested as problems reading mail; investigation showed that there was something up with NIS, which caused problems logging in, lsing files, and so forth.

The server seemed to be thrashing badly; most of the systems resources appeared to be devoted to the kswapd daemon. ypserv was running, but not listening to any network ports.

After trying various less drastic means to try to get the system working properly (including dumping it down to single-user mode and then back to network-server level, which initially seemed to work but didn't last), I rebooted the server. When it came back up, it (of course) had to run a check on the various /home filesystems. As these total around 200 GB, this process took a considerable amount of time. Once the checking was complete, the server came back up and appears to be running normally at this time.

I had been thinking about scheduling a reboot for this system in the near future, after classes and exams were over, so actually having to reboot it wasn't the worst thing in the world. (It had been running for 186 days without a reboot.) I do, however, apologize for any inconvenience you may have experienced when the server was unavailable.

If you notice any problems, please let me know ASAP so that I can take a look at them and get them resolved as quickly as possible.

Posted by C.M. Connelly | Permalink | Categories: System Maintenance, Linux