Best of Technical Support
My Dell arrived with factory-installed Red Hat 6.2, Kernel 2.2.14-6.1.1, and a factory-installed PCMCIA modem. All worked fine until one day, I turned on the PC and at bootup I was told:
Bringing up interface ppp0 FAILED
Somewhat later during bootup, this message appeared:
Couldn't configure serial #1 (port=760, irq=3): device already open serial_cs: register_serial() at 0x2f8 IRQ 3 failedThis modem card works fine in my Gateway Windows box. Dell refuses to help. —Steve Lohr, firstname.lastname@example.org
It's possible you have a program running that is tying up your serial port. Two common culprits are GPM, the text mouse dæmon, and one of several UPS monitoring dæmons. Use the ps ax | less command to look for such culprits. If you are still having problems identifying the culprit, try booting into single-user mode to shut down all unnecessary programs. Then use minicom to access the port directly, and verify that it can see your modem. —Chad Robinson, email@example.com
Perhaps a lock still exists from a previous session not ending normally. See if there are any old lock files in /var/lock, such as LCK..modem or LCK..ttyS1. If there are, just delete the files and reboot. —Keith Trollope, firstname.lastname@example.org
I am setting up a Linux machine that will masquerade my workstations and provide port-forwarding to my web/mail server. My question is, do I need an internal DNS server on my Linux machine to serve up DNS requests in order to browse the Web on my internal workstations? I would rather use the hosts file to define name-to-IP translations of my internal network. —Brandon Zumwalt, email@example.com
You do not need a DNS server on your Linux box, but you also cannot use the hosts file to perform this lookup. The hosts file is used by services running on your Linux box itself. Your first option is to configure your internal systems to use the DNS servers provided by your ISP. Once you have masquerading set up properly, your workstations will be able to access them and resolve web addresses without further work. Alternatively, you can set up a DNS server on the Linux box that will cache workstation requests. If you want to simplify this configuration, use the forward-only sample configuration for BIND. That puts the server into caching-only mode, with no local tables of its own. —Chad Robinson, firstname.lastname@example.org
Check your distribution's site for BIND security updates. Old versions of BIND, like the one that's probably on your distribution CD-ROM, are subject to automated attacks. Or run—Don Marti email@example.com
Is there a way I can have an X window appear on more than one X server (display)? I may want to do it (perhaps read-only) for, say, DVD output to displays throughout my home.
Separately, when I run an X application from a remote machine, how can I get the sound to follow and output on my local sound device? I only seem to be able to get sound out of a configured sound card for the host that owns the application. Similar to the above, can this be redirected to more than one address (back to my DVD playing in every room fantasy)? —Matthew Holmy, firstname.lastname@example.org
Xmx will allow you to display a normal X application on several X displays, http://www.cs.brown.edu/software/xmx/. However, for display speed reasons, some applications (like DVD players) bypass most of the X server when they write to your video card. Unless they have a slow, normal display mode, you can't do a remote display. You cannot send full framerate uncompressed video over Ethernet; it's too much data. You should, however, be able to rip a DVD on one machine, send it over the network and play it from disk on a different one. The network audio system lets you play sound over the network, radscan.com/nas.html. Another program you can look at is located at http://rplay.doit.org/. —Marc Merlin, email@example.com
I recently acquired a USB scanner (Epson Perfection 1640SU) and was successful in getting it to work with my Linux system (kernel 2.2.16-22). However, I need to modify one of the timeout parameters in scanner.h in the kernel source. How do I recompile this module to get scanner.o without having to recompile the entire kernel? Do I make a backup of /lib/modules/2.2.16 before I do this, and can it be safely restored in case of error? —Jin, firstname.lastname@example.org
After modifying the file, simply type make (target), e.g., make bzImage, from your /usr/src/linux or similar directory. This will recompile only the necessary files. The Makefile set for Linux has been altered to always compile certain files, such as main.c, but only a few files fit that category. All of the drivers should be skipped except the one you've changed. If you've changed only the .h file, the make program may not recompile your driver. Try touch scanner.c to simulate having made changes to the file. In addition, you can make your life a lot easier by simply using a module instead, in which case you would not need to recompile the kernel, only rerun—Chad Robinson, email@example.com
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.Register Now!
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- SourceClear Open
- SUSE LLC's SUSE Manager
- My +1 Sword of Productivity
- Managing Linux Using Puppet
- Google's SwiftShader Released
- Parsing an RSS News Feed with a Bash Script
- Non-Linux FOSS: Caffeine!
- SuperTuxKart 0.9.2 Released
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide