Virtual Domains and qmail
If you have hundreds of users for a virtual domain, you can avoid the hundreds of .qmail-xxx files with a small script that calls qmail's forward command.
Instead of creating individual .qmail-xxx files in the virtual domain master user's home directory, create a single .qmail-default file containing the following line:
with /home/master/qmail_db modified to reflect the home directory of your virtual domain. You can then create (or adapt from your existing /etc/aliases) the file /home/master/qmail_db, consisting of lines with the virtual domain user, a colon and the forwarding address(es). The special user name “-” indicates where mail should be forwarded for any users not explicitly listed. If the “-” user name is not provided, mail for nonexistent users will be bounced. A sample qmail_db file might look like this:
-: firstname.lastname@example.org john.smith: email@example.com carl.jones: firstname.lastname@example.org karen.quincy: kquincy all: email@example.com firstname.lastname@example.org kquincyNote the forwarding addresses for the “-” user must be an actual address; otherwise, mail to nonexistent addresses in the virtual domain will be accepted, but not delivered to anyone.
A more substantial package for supporting /etc/aliases, qmsmac, is available with qmail. qmsmac supports arbitrarily deep-nested aliases and long aliases but, like sendmail, requires you to rebuild a database of aliases every time your /etc/aliases file is changed.
qmail appears to be a speedy and robust replacement for sendmail. We've had qmail running on our Linux Internet server for many months now without a single glitch. The additional features provided by qmail could be useful to those of you hosting several virtual domains from a single Linux box, and the simpler configuration is an added bonus.
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!
- SUSE LLC's SUSE Manager
- My +1 Sword of Productivity
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Non-Linux FOSS: Caffeine!
- Managing Linux Using Puppet
- Doing for User Space What We Did for Kernel Space
- Tech Tip: Really Simple HTTP Server with Python
- SuperTuxKart 0.9.2 Released
- Parsing an RSS News Feed with a Bash Script
- Google's SwiftShader 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