Large-Scale Mail with Postfix, OpenLDAP and Courier
Most of the administration tasks, such as adding, modifying and deleting accounts and aliases, require modifying the LDAP directory. You can do this with the OpenLDAP command-line tools or a generic LDAP browser like gq. These methods are cumbersome, however, because they are generic tools and are not tailored to the task of administering e-mail accounts. We've been working on a web administration application called Jamm that is essentially an application-specific LDAP browser written in Java and JSP. It also has its own LDAP schema that is a slightly modified Courier schema. Jamm is currently usable and is constantly evolving. Visit the Jamm web page on SourceForge for the latest Jamm information.
When you create an account or an alias inside the LDAP database it will instantly become active as far as the mail system is concerned. For virtual accounts, note that the UNIX directory in ~vmail is not created at this time. However, we can work around this because Postfix's virtual delivery agent will create the necessary directories the first time it has to deliver mail. Due to this fact, we recommend sending a welcome e-mail as soon as you create the account.
When you delete an account or an alias in the LDAP database, it will instantly become inactive. For virtual accounts, note that the UNIX filesystem isn't cleaned up. In other words, the data remains on disk until a system administrator can remove it. This allows you to keep the data from dead accounts for a grace period in case the account was deleted in error. However, if another account is created with the same name and the same mail path, the data will be available to the new account. This could be considered a privacy violation for the previous user.
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.
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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