Best of Technical Support
I'm running Red Hat 6.1 on a Dell machine and I have DSL Internet access through Telocity. Until I got the Telocity service, my computer always thought of itself solely as “localhost.localdomain”. (For example, my bash prompt would read “[jenny@localhost tmp]$ ”). This seemed lame, but caused no problems. After Telocity came into my life, it mostly thought of itself as dsl-216-227-xxx-xxx.telocity.com. I'm not completely sure, but I think my prompt changed accordingly. After a recent reboot, though, we're back to “localhost.localdomain” and certain pieces of software with license managers that use the server's name are not working anymore. The licenses had been set up during the DSL phase. I've gotten them working again, but I'm afraid that one day my machine will go back to being dsl-blah-blah-blah and I'll have to fix it all again. Where does my computer's true identity reside? At what point in the boot process or on a running system does that get decided? How can I eradicate one of these identities entirely? What is the role of /etc/hosts? Could I have it both ways and have both entries in there? If so, would the IP address for dsl-blah-blah-blah need to be the loopback address 127.0.0.1, or my IP address from Telocity? For the record, the output from uname -n (today, at least) is localhost.localdomain. And here's my /etc/hosts file:
[root@localhost splus]# cat /etc/hosts 172.16.87.2 windoze.localdomain windoze 127.0.0.1 localhost.localdomain localhost
Thanks very much! —Jennifer Bryan, firstname.lastname@example.org
Red Hat keeps the machine name in three places: /etc/HOSTNAME (which is largely ignored; it's for compatibility with Slackware), /etc/sysconfig/network (HOSTNAME and DOMAINNAME) or /etc/hosts. You can change your machine's host name from the shell prompt with hostname:
moremagic:~# hostname foo moremagic:~# hostname foo moremagic:~# bash foo:~# exit exit moremagic:~# hostname moremagic.merlins.org moremagic:~# hostname moremagic.merlins.org
—Marc Merlin, email@example.com
Actually, your machine is “localhost.localdomain” when the Ethernet interface is down (ie the system is not connected to the network). Once the eth0 interface is up, the name of your system is “dsl-216-227-xxx-xxx.telocity.com”. According to the description of the problem, I think you don't use a fixed IP address, so your IP (and so your name) will change every time you reboot the system. If your license is configured for a static IP address, it would work only when your dynamic address matches the license address. I don't know a lot about your license manager, but maybe it's possible to use the Linux “dummy” net driver configured for the address defined in the license manager. Here is an example of dummy0 configuration on my system (assuming 192.168.3.3 is the static address used by license manager):
ifconfig dummy0 192.168.3.3 up route route add 192.168.3.3 dummy0
If connected to the Net, your system will reply both to the dynamic DSL IP address and the static dummy IP address. If not connected, the system will reply only to the dummy IP address used by the license manager. Another solution is to get a static DSL IP address from your ISP. It's more expensive, but will work every time. I don't think /etc/hosts could help you in case of dynamic IP. The file is useful for adding hosts name+address or name aliases you don't want to add to your DNS. —Pierre Ficheux, firstname.lastname@example.org
Okay, this is silly I think, but I can't find ANY info on it. My floppy worked until today; now when I click on it or try to mount it or try to access a file on it, or format it or put a file on it, I get an error message saying “mount: can't mount, dev/fd0 has wrong major or minor number”. What is this about? How can I fix it? —Sean Lafreniere, email@example.com
Here are the correct permissions and major/minor numbers for /dev/fd0 on Red Hat:
brw------- 1 root floppy 2, 0 May 5 1998 /dev/fd0
If they don't match, you can recreate them with mknod /dev/fd0 b 2 0. —Marc Merlin, firstname.lastname@example.org
Is it possible for a mouse to cause a system lock? When I am in an X session and I use my mouse (I've tried the Microsoft Intellimouse, and the Logitech First Mouse), sometimes my system locks up and I can't exit the session even forcefully. The mice I've been trying function normally otherwise, and I've tried using them in both PS/2 and serial ports with both the generic and specific drivers. This lock happens only when I use the mouse, but it doesn't happen immediately—it can happen after five minutes of use or 45 minutes of use. There doesn't seem to be a pattern. The techs at Red Hat didn't have a clue, and I'm getting pretty desperate. Any help would be greatly appreciated. —Mike, email@example.com
Considering that a PS/2 mouse uses interrupt 12, which no self-respecting motherboard should assign to anything else, unless you have an ISA card that uses that interrupt, it's probably not a mouse conflict. It's not necessarily the mouse; it could simply be your X server or your graphics card. Try to see if upgrading X works, and if that still doesn't help, try swapping the graphics card with another type. —Marc Merlin, firstname.lastname@example.org
If this happens only with PS/2 mice, then it may be due to a problem in some versions of the kernel driver. A PS/2 mouse is managed by the keyboard controller, so if you lose one, you lose both. Try upgrading to the latest version of the kernel release you are using. Since you report the problem with any kind of mouse, I don't think it's related to mouse activity. Please try to resort to the “Magic SysRq” feature to print out some system information when the lock happens. Using the magic SysRq feature, you should also be able to kill X; if not, you should reproduce the problem in text mode. If no information can be extracted, then the system is locked hard, and it looks more like a hardware problem than a software one. Maybe the processor shuts down for overheating or something similar. —Alessandro Rubini, email@example.com
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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.
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