Best of Technical Support
I cannot log on. My old password doesn't work. I am the root on this system. How can I change the password or verify my old password? —Kevin Cary Red Hat 2.0.30
This is a much debated topic since it essentially involves breaking your system's security. The main discussion point always seems to be how to do it without letting people do it to others. For the most part, it is easy to remove the root password from Linux (and many other flavors of Unix) servers, as long as the machine has a floppy drive that it boots from by default.
If you have a standard Linux system without shadow passwords, you can simply boot from a “boot and root” floppy disk set, mount your partition and edit the /etc/passwd file. In this file, fields are separated by the colon (:) character. The second field on the first line can be removed (so the entry looks like ::) and root will no longer have a password. You can then reboot, log in as root and use passwd to set the new root password. —Chad Robinson, BRT Technical Services Corporation email@example.com
Which distribution should I download? Sorry about this low-level question, but I couldn't find help elsewhere. —Erik Rask
That's a question that can easily spark religious debates, but I'll side step that issue and just mention that there's a rather well-written Distribution HOWTO available from any Linux Documentation Project mirror (i.e., http://www.silug.org/LDP/) that describes the differences between distributions. —Steven Pritchard firstname.lastname@example.org
I need help in determining why my modem connection is so slow. I have a 33.6Kb modem that runs fine in Windows, but I just haven't found all of the files I must edit for making pppd run as fast as possible. —Paul Carff
pppd has a setting called asyncmap, that is a mask of characters which it must escape. This masking allows pppd to be run across lines that may not handle all 256 characters of the ASCII set. A common example of this is a line that must use software flow control in the form of the ctrl-S and ctrl-Q characters to pace the flow of data. pppd cannot send those characters directly since they would interfere with the operation of the flow control; so, it sends another two characters (the escape and the replacement character) instead.
If no asyncmap parameter is set (as described in the pppd man page), pppd will automatically escape all control characters just to be sure the transmission is not interrupted. Obviously, this adds a good deal of overhead to the transmissions. Setting the asyncmap to 0 results in a noticeable increase in transfer rates on most systems. —Chad Robinson, BRT Technical Services Corporation email@example.com
I just installed Red Hat 4.1, and I made a mistake while setting up the mouse. I set the mouse port to 1, but the real mouse port is 2. How can I change the mouse port?
—Moon Ill June
The best way is to run mouseconfig from the command line. It will let you choose the port just as you did at install time. —Donnie Barnes, Red Hat Software firstname.lastname@example.org
I am running 2.0.7 and have tried to compile the kernels of 2.0.27, 2.0.30 and 2.1.x, all of which give me the same error on execution. All of the kernels compiled successfully, but they crashed on bootup with the message “kernel stack corruption”. What could be wrong? —Thomas S. Chin
Start by using a good memory checker to check your system RAM. The kernels you listed are known to be stable, and the kernel stack is somewhat difficult to corrupt since it's well protected by the operating system.
Also, investigate your BIOS settings to make sure they match your memory type and CPU-cache type. If it can be set, be sure your BIOS has the same speed setting (60ns or 70ns) as your system RAM and your cache type (write-back, write-through, et cetera) matches what you actually have. —Chad Robinson, BRT Technical Services Corporation email@example.com
I like color as a means of segregating data and reducing eye strain. I looked at all the escape sequence information I could find and set PS1 (where _ is a space) to:
The user name is cyan, the directory and root prompt are brown and the rest is green. However, when I try to edit a history command, strange things occur when backspacing and the command text becomes jumbled. What am I missing? —Jim Red Hat 4.1
The shell probably doesn't care what escape sequences you use. The problem area is more likely your terminal. Investigate the terminal program you are using to log in and be sure it supports proper ANSI sequences. Be sure that it properly handles setting a color when another is already set. Never turn off colors at the end of your prompt. Try an esc[0m at the end of the line (sacrificing color for the text you type) and see if that helps.
This is especially true since a colorized ls listing causes trouble for you. The listing is turning on and off individual colors (with the default ls settings), and terminals that don't support it will have problems with pre-existing color settings. —Chad Robinson, BRT Technical Services Corporation firstname.lastname@example.org
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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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