Best of Technical Support

Our experts answer your technical questions.
SCSI Emulation for Just One Drive

I have an HP IDE CD-Writer, so I am using SCSI emulation to use it with cdrecord. Under the 2.2.18 kernel, I could tell the ide-scsi module only to make use of my burner and leave my ATAPI CD-ROM alone. I did this via an append option in lilo.conf:

append="hdc=ide-scsi"

This worked well, as /dev/hdc is my burner and /dev/hdd is my ATAPI CD-ROM. Unfortunately, under the 2.4 kernel, this no longer works. The ide-scsi module grabs both devices, making /dev/hdd unavailable, preventing cdparanoia from working with it and forcing me to mount it with /dev/scd1. How do I get the same effect under 2.4 and force the ide-scsi module to emulate only /dev/hdc?

—Michael Soulier, michael.soulier@home.com

What you want is for hdc to do SCSI emulation and hdd to continue to be used as an IDE device. Usually IDE-CD support is disabled and SCSI emulation is enabled so that both drives are seen as SCSI devices. See www.wizball.co.uk/linux/cd_rewriter.php and www.teknospy.com/pages/howtos/cdburn.php for tutorials.

—Paul Christensen, pchristensen@penguincomputing.com

What Does This RPM Depend On?

I maintain 39 Red Hat servers and am always adding more (web hosts). I always try to install the bare minimum of packages during an install, figuring that if I don't include something the customer decides they want later, I can always figure out how to add it. Occasionally, a package requested will have such a fun list of dependencies requested that what should be a simple rpm -ivh package.rpm becomes a 30 minute dependency adding game. Is there a simple switch I can enter to have RPM tell me what one package needs before I try to install it?

—Bruce D. Meyer, gh1@rocsoft.net

You describe one of the reasons why many Linux server administrators use Debian Linux instead of a Red Hat derivative. With Debian, it is just a matter of typing apt-get install foo. Last I checked, RPM doesn't have a magic switch to do what you want. One way to do this on Red Hat is to use gnorpm or rpmfind. The problem is that in either case, with RPM-based solutions, RPMs are often incompatible across distributions and even within different versions of the same distribution (like RH 6.2 and RH 7.1). While rpmfind/gnorpm will probably be your best bet, if you get the option to install Debian Linux next time, it would solve all these problems.

—Marc Merlin, marc_bts@valinux.com

One little gem is Red Carpet. Documentation and downloads can be found at the www.Ximian.com web site.

—Paul Christensen, pchristensen@penguincomputing.com

Welcome, Guest Printer Users

I have a Linux box that acts as my DHCP server, firewall and gateway to the Internet. Many of my clients are visiting Windows users. Is it possible to set up the Linux box to be a print server such that a Windows client can print via the Linux print server without the client having to install printer drivers?

—Danny Patel, dharmesh@yahoo.com

I would set up a Samba Share for both the printer and the Windows drivers for that printer.

—Christopher Wingert, cwingert@qualcomm.com

You might want to look into using CUPS (Common UNIX Printing System). It supports IPP, LPD, SMB (Windows) and AppSocket (JetDirect) protocols.

—David Brown, david@caldera.com

cron Won't Run a Shell Script

I can't execute a shell script with crontab. I get this error:

cannot execute binary file

—Leonardo Fermoselle, lfermose@hotmail.com

Does your script start with #!/bin/sh as the very first characters of the file? It should. If this isn't the problem, was the script written on a DOS machine? Open the file with the joe text editor and if you see funny M characters at the end of every line, that is your problem. You can use a tool found at freshmeat.net/projects/fixdos to fix that.

—Ben Ford, ben@kalifornia.com

Run the command file /usr/backup/myscript.sh, or load this file in vi and make sure it does not have any junk characters in the file. Make sure that you can run the script from command line.

—Usman Ansari, uansari@yahoo.com

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