Best of Technical Support
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, email@example.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, firstname.lastname@example.org
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, email@example.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, firstname.lastname@example.org
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, email@example.com
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, firstname.lastname@example.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, 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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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