LJ Archive

Best of Technical Support

Various

Issue #100, August 2002

Questions and Answers

Where's My FireWire CD-ROM?

I recently bought a Sony R505 laptop and when I tried to install SuSE Linux, I discovered that after the boot, Linux could not see the CD-ROM. It turned out that the docking station where the CD-ROM lives is accessed from the computer via FireWire somehow.

—Steven Smith, sjs@chaos-tools.com

Your confusion may be due to differing procedures for the various distributions available. For SuSE, there is a basic HOWTO guide in their knowledge base, which you can access by visiting sdb.suse.de/en/sdb/html/tbraza_dosinst.html. This should get you headed in the right direction.

—Chad Robinson, crobinson@rfgonline.com

I Have No Qt and I Must Run KDE 3.0

Are there RPM packages for the latest versions of Qt and KDE?

—Dan, dhdeang@SoftHome.net

To locate RPMs, I find rpmfind.net to be a helpful portal. In this case, there is a page specifically for Qt and KDE: rpmfind.net/linux/RPM/Development_KDE_and_QT.html. On that page I note that Qt 3.x is still listed as a development package, but it is available.

—Chad Robinson, crobinson@rfgonline.com

Raiders of the Lost DDS-3 Tape

I'm trying to read a DDS-3 tape made on an HP9000 machine running HP-UX 11. I'm trying to read it using my Linux server that runs Red Hat 7.2 (2.4.9.31SMP kernel). The Linux server tape drive is a Sony SCSI device, /dev/st0. The tape contains Oracle export files of a large Oracle database. The HP machine is no longer available, and I'm trying to rebuild the DB on Linux. When I try to read the tape with either tar -tvf /dev/st0 or tar -xvf /dev/st0 I always get:

Input/Output error at the beginning of the tape, error is not
recoverable, exiting now

Why?

—Adrian Manship, adrian.manship@skynet.be

Check two things related to the tape drive. First, DDS drives support the concept of hardware compression, which may have been used by HP-UX and may not be enabled by Linux. If there is a mismatch in this setting, that can cause problems reading the tape.

Second, although tar itself is a relatively standard format, is it possible that the tape was not created using tar? Depending on the version of Oracle used to create the tape, it may have internal support for reading/writing tape devices as backup media. Check a small sample of the file to be sure it is actually in tar format by running dd if=/dev/st0 of=/tmp/tape bs=512 count=16, replacing the bs value with a block size that works well for your drive and the count value with a count that yields a sufficient number of those blocks to take a quick look. This example will read 8K from the tape.

Perhaps the tape itself is bad. If it succeeds, you should be able to use a hex editor or text editor that can handle high-ASCII characters without choking to verify the format of the contents of the tape. In case you aren't familiar with the general format, each file entry should start with its filename, followed by a header that contains miscellaneous file information such as size and permissions, followed by the file itself.

—Chad Robinson, crobinson@rfgonline.com

The easiest thing to do, would be to buy/borrow/steal a similar machine to do the restore.

—Christopher Wingert, cwingert@qualcomm.com

I used to work with HP-UX DDS tapes, and most of the time they were used with the cpio utility. Keep in mind that cpio is a complicated utility with many options, so check the manual pages (man cpio) and play around with some of the options. Be careful not to write your tape accidently; I suggest that you physically enable the write-protect feature on the cartridge. Look at www.lns.cornell.edu/public/COMP/info/cpio/cpio_2.html for a simple cpio tutorial.

—Felipe E. Barousse Boué, fbarousse@piensa.com

No Screensaver for root

When I sign on using root, the screensaver does not work. When I sign on with another ID, it does. How can I make it work when signed on as root?

—James Logan, jlogon@mail.ewu.edu

xscreensaver will not work as root on purpose. It's a security feature; you're not supposed to run X as root (log in as a user and use su - where needed). This is explained in the FAQ, along with a solution to how to run X programs as root if you need to (www.jwz.org/xscreensaver/faq.html#root-lock).

—Marc Merlin, marc@merlins.org

New Install Won't Boot

I attempted to install Red Hat 6.2 on my spare machine. The install ran fine and completed. I removed the disks and rebooted, and I keep getting a nonsystem disk error telling me to replace the disk.

—Tim Dreas, timdreas_@hotmail.com

It seems like either LILO or GRUB, the boot loaders, were never installed correctly. If you made a rescue disk during the installation (of course you did, right?), use it to boot your computer. When you get the root Linux shell prompt (#), type lilo -v, which should attempt to write the boot loader into your hard disk.

—Felipe E. Barousse Boué, fbarousse@piensa.com

How Do I Remove a User

How do I remove a user from a group? (We deleted the user and now are receiving error messages that there is a permanent fatal error when someone e-mails this group.) How do we correct this?

—Barbara Viola, bviola@viotechsolutions.com

I assume you mean mail alias and not a UNIX group. Check out /etc/aliases and remove the user. Then run newaliases.

—Christopher Wingert, cwingert@qualcomm.com

To remove a user from a group, not just from an e-mail alias, use the gpasswd command as root:

gpasswd -d name_of_deleted_user

Take a look at man gpasswd. It gives an explanation and options for other group administrating functions.

—Paul Christensen, pchristensen@penguincomputing.com

I Have No Static IP Address and I Must SMTP

Is it possible to have an internet mail server with a dial-up connection to an ISP? I know that the IP address of ppp0 may change whenever I establish a new connection with the ISP. The MX records need to point to the mail server; the IP address of the server also must be specified at dewdesigns but will not be valid if or when I get a new connection. Do I need to run DNS locally or can I use the ISP DNS? I recently read an article by Marcel Gagné regarding small-office mail servers, but I feel that I am missing some pieces of the puzzle.

—Daryl E. Murray, daryl@Planet4us.net

There are ways to have an SMTP server on a dial-up dynamic IP and set up DNS so that it gets updated every time you change your IP address, but trust me, you do not want to go there. Short of running UUCP, which is the correct way to route mail in your case (UUCP is quite old, not well-known by most system administrators and probably not supported by your ISP), you should use Fetchmail to download your mail. If you need to download mail for many accounts, you can have your ISP spool all your mail in one mailbox, download that with Fetchmail, and split it up again, looking at the Envelope-To: field or whatever field in which your ISP stored the original Envelope-To.

—Marc Merlin, marc@merlins.org

You only can use Fetchmail to download all of your site's mail if your ISP consistently applies an Envelope-To: header to your mail. See the warning at www.catb.org/~esr/fetchmail/fetchmail-man.html#25.

If you have a dial-up with a static IP address, and your ISP is willing to queue incoming mail for you, you can do an SMTP ETRN when the connection comes up. Sendmail includes a utility to do this.

—Don Marti, info@linuxjournal.com

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