Linux

It helps to know how things work

Linux Opinion Technical Training

It really helps to know how things work when it becomes necessary to fix them.

This was true when I was fixing audio equipment in the early ’70s, and supporting computers and software for IBM, MCI, Interpath, and Cisco over the years, and teaching Linux for Red Hat and my own company, Millennium Technology Consulting LLC. The intimate knowledge of how Linux works has also been invaluable since I started working with it in about 1996.

Unless you know how things really work, there is a tendency to use a shotgun approach to problem solving. That wastes time and, if replacing parts is involved or purchasing new software, can be quite expensive.

After all, would you be willing to pay for the auto mechanic to replace several perfectly good parts while trying to find the one part actually causing the problem – and to pay him for time and materials as well? Of course not. Although that used to be the case more often than it should have been.

I submit for your approval a problem I just fixed this morning – with this web site.

It was not a problem that affected the external operation of the DataBook web site, but I could no longer use any editor from within WordPress to edit pages and posts such as this one.

Because I know several important things about WordPress I was able to think about the problem and correct it on the first try. I know the following about WordPress:

  • The data for WordPress web sites is stored separately in a MySQL database. Separation of data and code is always a good thing to do.
  • There is one and only one, small site configuration file for each WordPress web site, wp-config.php.
  • All WordPress plugins, themes, and uploaded graphics also have their own directories.
  • The Apache web configuration is separate from the WordPress site configuration.

So it was a simple matter to simply delete the entire directory in which the WordPress instance was installed for that web site. Everything.

I then copied the entire directory structure from a known working web site to replace the one I deleted. I then copied the original wp-config.php to the appropriate location in the newly copied WordPress directory structure and my web site was up and running again. It was then trivial to copy from backups the rest of the plugins and graphics to complete the process. All in all it took less than 5 minutes.

Not having the understanding I do of how WordPress, MySQL and Apache work together to produce a web site, I would have been tempted to simply delete everything in the WordPress directory (/var/www) for that web site and start over by reinstalling WordPress and configuring it from scratch. As easy as that is for WordPress, it would still have taken much longer than it did for me to actually fix the problem.

If I had understood more about the PHP coding of WordPress itself, I probably could have simply repaired the offending file that was likely corrupted for some reason. But that would probably taken much longer in any event.

If you are interested in learning how Linux works so that you can identify, understand and fix problems in the most effective ways, try the Linux classes I offer at Millennium Technology Consulting LLC.

CentOS 7.0 released

Linux News

CentOS 7 was released today, July 7.

CentOS is identical to Red Hat Enterprise Linux (RHEL) with the only exception being the branding text and graphics. CentOS is a fully supported Community ENTerprise Operating System that provides free upgrades and support.

CentOS 7 incorporates several major changes and enhancements. These includes things like systemd and GNOME 3. In addition, the XFS file system is now the default.

Many of the new features in CentOS, such as systemd, have been around for a couple years, most notably in the Fedora distribution. Fedora is the upstream feeder to RHEL and many new RHEL features are first introduced in Fedora.

See http://www.centos.org/ for more details anout CentOS 7.

Free “Introduction to Linux” course from the Linux Foundation, edX, MIT and Harvard

Linux News Training

Free classes are always cool, especially in times when companies do not have big training budgets. And it seems like one of the best training opportunities in years is here.

Linux is hot as a job skill. The Linux Foundation’s 2014 Linux Jobs Report found that 90 percent of hiring managers are looking to hire Linux professionals in the next half-year. But demand is greater than supply. Not only is Linux hiring hot, but Linux professionals are also getting larger and more frequent pay raises.

The Linux Foundation along with edX and major educational institutions Harvard and MIT have combined to provide a Massive Open Online Course (MOOC), Introduction to Linux. This course is free of charge and you can take it to earn a certificate or you can audit the course if you cannot make the full time commitment.

The course will be available some time in the 3rd quarter of 2014. The folks at VentureBeat have a short writeup about this which sounds quite interesting. You can read about the course and register here. It is estimated that the time commitment if you take this course is 40 to 60 hours.

Now you might ask why, as a Linux trainer, I would suggest you take this course rather than mine? Well, free is free, right?

I do plan to take this class myself as there is always more to learn. I enjoy teaching my own two-day “Introduction to Linux” course, and I do get paid for it. So, again, why? Because I cannot imagine that anything done by the Linux Foundation and the combination of organizations that have put this course together would not be really, really good.

Opportunities like this do not come along frequently. Take advantage of it.

Training Calendar set for first half of 2014

Linux News Training

Millennium Technology Consulting LLC has finalized its class schedules for the first half of 2014.


Training Calendar for First Half of 2014
Course Date Availability
Theory and Practice of Linux System Administration February 24 – 28  Seats available
Linux Servers and Advanced System Administration March 17 – 21  Seats available
Theory and Practice of Linux System Administration March 31 – April 4  Seats available
Linux Servers and Advanced System Administration April 14 – 18  Seats available
Theory and Practice of Linux System Administration April 28 – May 2  Seats available
Theory and Practice of Linux System Administration May 19 – 23  Seats available

Theory and Practice of Linux System Administration

This course is intended for trainee or  junior Linux Systems Administrators who wish to advance their knowledge, and administrators of other Unix versions or Windows who wish to become Linux System Administrators. This class is heavily oriented towards hands-on activities. At least half of the class time is allotted to lab projects.

CentOS

This class is taught using CentOS because it is the downstream distribution of Red Hat Enterprise Linux (RHEL) and is identical in every way except for branding. There will be some discussion of the features found in Fedora and which may appear in future versions of RHEL and  CentOS.

See the Theory and Practice of Linux System Administration page for a complete course description and prerequisites.

Linux Servers and Advanced System Administration

This course is intended for experienced Linux System Administrators who wish to learn advanced troubleshooting techniques and server installation and configuration. By the end of the class each student will have a fully working Linux system with a firewall; a name server with forward and reverse zones; a DHCP server; an email server with integrated anti-spam; two working web sites with one a static HTML site and the other a complete WordPress site with a MySQL back end; A MailMan mailing list server; A VNC server; NFS and Samba shares. The student will also learn to build RPM packages.

See the Linux Servers and Advanced System Administration  page for a complete course description and prerequisites.

Discounts

Discounts are available to members of the Triangle Linux Users Group (TriLUG) of $500 per class. You must have and show your TriLUG membership card to obtain this discount. This discount may be used in conjunction with other discount offers.

Custom Class Scheduling

Millennium Technology Consulting LLC can provide customized scheduling for classes. If you do not see a class scheduled within your desired time frame we can work with you to schedule one that meets your needs. We also offer on-site training at your location. Please contact us to schedule a class for you.

Theory and Practice of Linux System Administration class, January 20 – 24

Linux News Training

Millennium Technology Consulting LLC, will be running the highly reviewed class, Theory and Practice of Linux System Administration, the week of January 20 – 24.

About this Course

This course is intended for  junior and mid-level Linux Systems Administrators who wish to advance their knowledge, and administrators of other Unix versions or Windows who wish to become Linux System Administrators. This class is heavily oriented towards hands-on activities. At least half of the class time is allotted to lab projects.  Experienced Linux System Administrators also find this class valuable. Taken from my own experiences accumulated during more than 15 years of using Linux, and developed using my knowledge and experience as a course developer and trainer for both IBM, Red Hat, and other companies, this class covers the practical aspects of Linux System Administration. It builds upon the foundation of the “Philosophy of Linux” in a way that helps the student understand how and why things are done as they are.

Our courses are always highly rated and well reviewed. Here are some comments from previous students taken directly from the course evaluation forms.

Course Description

The student will learn about the history of Linux and the philosophy of Linux and how it applies to the everyday tasks that she will be expected to perform. The student will install a current Centos Linux system on common Intel hardware, using various installation options to customize the final result. The students will learn to use the command line interface (CLI) and many basic Linux commands along with the vi editor. More advanced commands such as sed and awk will be covered and combining all of these commands into short command line programs will be discussed and the student will have opportunity to use them in lab projects.

This course covers the Linux boot sequence and the traditional SystemV init scripts as well as an introduction to the new systemd daemon for startup and daemon management. The student will learn to manage users and software packages. Networking, security, processes, filesystems and Logical Volume Management will be covered in detail.

For complete details of this course see the Theory and Practice of Linux System Administration page.

Theory and Practice of Linux System Administration class, November 11 – 15

Information Linux Training

For the last time this year, Millennium Technology Consulting LLC, will be running the highly reviewed class, Theory and Practice of Linux System Administration, the week of November 11 – 15.

About this Course

This course is intended for  junior and mid-level Linux Systems Administrators who wish to advance their knowledge, and administrators of other Unix versions or Windows who wish to become Linux System Administrators. This class is heavily oriented towards hands-on activities. At least half of the class time is allotted to lab projects.  Experienced Linux System Administrators also find this class valuable.Taken from my own experiences accumulated during more than 15 years of using Linux, and developed using my knowledge and experience as a course developer and trainer for both IBM and Red Hat, this class covers the practical aspects of Linux System Administration. It builds upon the foundation of the “Philosophy of Linux” in a way that helps the student understand how and why things are done as they are.

Our courses are always highly rated and well reviewed. Here are some comments from previous students taken directly from the course evaluation forms.

Course Description

The student will learn about the history of Linux and the philosophy of Linux and how it applies to the everyday tasks that she will be expected to perform. The student will install a current Fedora Linux system on common Intel hardware, using various installation options to customize the final result. The students will learn to use the command line interface (CLI) and many basic Linux commands along with the vi editor. More advanced commands such as sed and awk will be covered and combining all of these commands into short command line programs will be discussed and the student will have opportunity to use them in lab projects.

This course covers the Linux boot sequence and the traditional SystemV init scripts as well as an introduction to the new systemd daemon for startup and daemon management. The student will learn to manage users and software packages. Networking, security, processes, filesystems and Logical Volume Management will be covered in detail.

For complete details of this course see the Theory and Practice of Linux System Administration page.

Theory and Practice of Linux System Administration class, August 17 – 23

Linux News Training

I will be running the highly reviewed class, Theory and Practice of Linux System Administration, the week of August 17 – 23.

About this Course

This course is intended for  junior and mid-level Linux Systems Administrators who wish to advance their knowledge, and administrators of other Unix versions or Windows who wish to become Linux System Administrators. This class is heavily oriented towards hands-on activities. At least half of the class time is allotted to lab projects.  Experienced Linux System Administrators also find this class valuable.

This class is based on Fedora because it is the upstream distribution for Red Hat Linux.

Taken from my own experiences accumulated during more than 15 years of using Linux, and developed using my knowledge and experience as a course developer and trainer for both IBM and Red Hat, this class covers the practical aspects of Linux System Administration. It builds upon the foundation of the “Philosophy of Linux” in a way that helps the student understand how and why things are done as they are.

Our courses are always highly rated and well reviewed. Here are some comments from previous students taken directly from the course evaluation forms.

Course Description

The student will learn about the history of Linux and the philosophy of Linux and how it applies to the everyday tasks that she will be expected to perform. The student will install a current Fedora Linux system on common Intel hardware, using various installation options to customize the final result. The students will learn to use the command line interface (CLI) and many basic Linux commands along with the vi editor. More advanced commands such as sed and awk will be covered and combining all of these commands into short command line programs will be discussed and the student will have opportunity to use them in lab projects.

This course covers the Linux boot sequence and the traditional SystemV init scripts as well as an introduction to the new systemd daemon for startup and daemon management. The student will learn to manage users and software packages. Networking, security, processes, filesystems and Logical Volume Management will be covered in detail.

For complete details of this course see the Theory and Practice of Linux System Administration page on our Millennium Technology Consulting LLC company web site.

Introduction to Linux class, August 8 and 9

Announcements Linux Training

I am running an Introduction to Linux class this Thursday and Friday, August 8 and 9.

This two-day course is for anyone who is considering pursuit of a course in Linux system administration and who wants a brief introduction to Linux.

Course Outline

This course is a quick survey of various aspects of using Linux with both the desktop and the command line interface (CLI). It is intended to be an introduction to Linux for someone who intends to be more than a casual user of Linux and covers some basic non-privileged administrative tasks. It also introduces a few of the basic concepts and some of the basic tools used by the root user.

The topics covered in this course include the following.

  • Exploring desktops
    • KDE
    • GNOME
    • Other desktops
  • Virtual Consoles
  • Screen
  • The Command Line Interface (CLI)
  • Processes
  • Managing Files
  • Vim Editor
  • More About Files
    • Permissions
    • Links

The course normally costs $1295 however there is a $500 discount for TriLUG members.

See http://www.millennium-technology.com/?page_id=1519 for full course details.

Linux Servers and Advanced System Administration class scheduled for June 10 – 14

Announcements Linux Millennium Technology Consulting LLC Training

Millennium Technology Consulting LLC has scheduled its course, Linux Servers and Advanced System Administration for June 10 – 14, 2013.

This unique 5-day class, entitled, Linux Servers and Advanced System Administration covers a wide range of advanced topics in a manner never seen in other courses.

The topics covered in this course are:

 Administrative Tools  WordPress and MySQL
 IPTables  MailMan
BIND DNS  VNC
DHCP  NFS
Network Configuration  SAMBA
SSH  NTP
SendMail  CUPS
SpamAssassin  SELinux
MIMEDefang  Building RPMs
Apache Web Server

But it is how the class is structured as much as the specific subjects covered that makes it unique. Most classes that cover these subjects do not cover all of them, and they do not treat them as a part of an integrated whole system. The Linux Servers and Advanced System Administration class treats these as parts of a unified whole

By the end of the class each student will have a fully working Linux system with a firewall; a name server with forward and reverse zones; a DHCP server; an email server with integrated anti-spam; two working web sites with one a static HTML site and the other a complete WordPress site with a MySQL back end; A MailMan mailing list server; A VNC server; NFS and Samba shares. The student will also learn to build RPM packages.

In addition, students will learn advanced aspects of some of the system commands covered in my Theory and Practice of Linux System Administration course, as well as some interesting new commands that can be used for advanced system administration tasks and problem determination.

Linux Servers and Advanced System Administration – Seats for this 5-day course are available and cost $2995.00. Please contact us to sign up for classes as soon as possible. Our classroom facilities are very limited so class sizes are very small.

 

More about Fedora 18

Information Linux Reviews Technical Tips and Tricks

In my review of Fedora 18, I discussed my initial impressions of that newest release. Having now begun to install Fedora 18 on several more hosts in my constantly changing world I have found some interesting under the cover changes.

firewalld

A new firewall, firewalld, is now the default firewall for Fedora. Of course Fedora is the proving ground for many new things so, while this change was not particularly well documented, changes to Fedora in general should not be a surprise. The firewalld daemon is mentioned in three short paragraphs in the Fedora 18 release notes which only references the man pages for the new firewalld commands for further information, and once as being a new addition in the Technical Notes document. Both are available as PDF files from the Fedora Documentation Project.

The firewalld rules are quite complex compared to what I have been using with IPTables. This, and the fact that I am not yet familiar with the rule syntax or the overall structure of firewalld means that, for now at least, I need to revert to IPTables on my Fedora 18 hosts.

Reverting to IPTables

The good news is that the old IPTables firewall is still available until I can learn how to best create the firewall rules I need with firewalld. However it, too, has changed and some of the old IPTables rules, especially those using state related rule sets have been altered.

First, to convert back to IPTables, stop and disable the firewalld service and start and enable the iptables service.  Of course you must do this safely with your network disabled until you can get your new (old) firewall back in place. Then use the iptables-restore command to restore your old IPTables rules from the saved copy. You did save a backup copy of your IPTables firewall rules, right?

At this point, IPTables gives some errors indicating that one should use new connection tracking rules in lieu of the state-related rules. The best part is that IPTables is smart enough to give you the warning message and then translate the rules into connection tracking rules. At that point you can simply use the iptables-save command view the translated rules and redirect the output to /etc/sysconfig/iptables to save the translated rules.

So now I will take some time to learn this new firewall system while my IPTables firewall protects me.

Here is a link to the Fedora Project FirewallD documentation. http://fedoraproject.org/wiki/FirewallD

Millennium Technology Consulting LLC Adds “Introduction to Linux” Class

Announcements Linux Millennium Technology Consulting LLC Training

Millennium Technology Consulting LLC announces the availability of the newest class in its training line-up.

The Introduction to Linux course provides a two-day survey of various aspects of using Linux with both the desktop and the command line interface (CLI). It is an introduction to Linux for someone who intends to be more than a casual user of Linux and covers some basic non-privileged administrative tasks. It also introduces a few of the basic concepts and some of the basic tools used by the root user.

View the Introduction to Linux course page on the Millennium Technology Consulting LLC web site for additional details about this course.

“Linux Servers and Advanced System Administration” Class Status

Linux Millennium Technology Consulting LLC News Training

The advanced class I have been working on for over a year is nearly ready. This unique class, entitled, Linux Servers and Advanced System Administration covers a wide range of advanced topics in a manner never seen in other courses.

The topics covered in this course (still subject to change) will be:

 Administrative Tools  WordPress and MySQL
 IPTables  MailMan
BIND DNS  VNC
DHCP  NFS
Network Configuration  SAMBA
SSH  NTP
SendMail  CUPS
SpamAssassin  SELinux
MIMEDefang  Building RPMs
Apache Web Server

But it is how the class is structured as much as the specific subjects covered that makes it unique. Most classes that cover these subjects do not cover all of them, and they do not treat them as a part of an integrated whole system. The Linux Servers and Advanced System Administration class treats these as parts of a unified whole

By the end of the class each student will have a fully working Linux system with a firewall; a name server with forward and reverse zones; a DHCP server; an email server with integrated anti-spam; two working web sites with one a static HTML site and the other a complete WordPress site with a MySQL back end; A MailMan mailing list server; A VNC server; NFS and Samba shares. The student will also learn to build RPM packages.

In addition, students will learn advanced aspects of some of the system commands covered in my Theory and Practice of Linux System Administration course, as well as some interesting new commands that can be used for advanced system administration tasks and problem determination.

I expect this course to be ready for a test class in December of 2012. It will be held in my Raleigh, NC, training facility. The exact date is still a bit uncertain but, at this time, I expect it to be the first week of December.

The class will normally cost $2995. There will be discounts available for that session because it will be a test class. As always, the additional $500 discount for TriLUG members will apply. Please contact Millennium Technology Consulting LLC for details.

Fedora 17 Released

Linux News

Fedora 17, the latest in a long series of Fedora Linux releases, was released on Tuesday, May 29. Code named “Beefy Miracle,” it offers many new features and upgrades.

I have already installed it on my primary workstation which I don’t recommend for most people to do on day 1 of any release. I also installed Fedora 17 onto a VirtualBox VM where I will do my best to break it. Hopefully it will not break my primary workstation.

Here are a few of my first impressions.

In Brief

I have already noticed significant speed improvements over Fedora 16 and previous releases. KDE screen animations and effects are enabled by default, possibly as a result of the speed gains, and they make for a fun desktop. Perhaps the new 6.3.3 kernel is at least in part responsible for the speed gains.

The BTRFS filesystem is no longer an option during installation, but can be used on partitions formatted after installation. This is due to issues with the filesystem. I have also had problems in the recent past with installations using EXT4 so I personally do not use that for the main installation.

I had problems with the upgrade from DVD so had to do a complete installation. I was able to save my home filesystem and restored other critical data from backups so it was not a major issue. I always expect problems with upgrades and new installations, so no real surprise there. I think the issues may be due to the non-Fedora repositories I have configured, but I need to experiment more with that.

In general everything seems to be working well so I am happy.

I will write a more compete review as soon as I have more experience with this release.

 

Install Issues with Fedora 16 and EXT4 Filesystem

Information Linux Technical

I just had an interesting experience while installing Fedora 16 on my primary workstation. It took me about 3 days and many attempted installations to figure this out. This is not a review, just a bit about my experience.

At first I wiped out my hard drive entirely since it has been several years since I did a really clean installation. That is, a complete wipe out of my hard drives—after first making certain that I had multiple good backups. Over time much cruft can accumulate from old application configuration and data and I wanted to get rid of everything except data I really wanted to keep.

Symptoms

The initial installation of Fedora 16 appeared to go well using the default choice of EXT4 for the filesystem type. After starting to make configuration changes and restoring a few directories in my non-root user home directory, KDE started crashing on a regular basis. It would indicate problems with Segment Faults. This is not good and can mean many bad things.

After installing several times with similar results, I decided to go back to Fedora 15. During the installation, I used EXT3. I had previously experienced an occasional problem with Fedora 15 while using EXT4, but nothing particularly repeatable. Many of the problems were during installation using EXT4 and I would get errors indicating that a specific package was not able to be installed. Looking at the log terminal (Ctrl-Alt-F3) most errors appeared to be on the DVD, but the DVD always tested as having no defects at the beginning of the installation.

Solution

My decision to use EXT3 was kind of on a whim, but the next install went without problems and I had no problems doing basic configuration. So I decided to reinstall Fedora 16 using EXT3 instead of EXT4 and have had no problems since. This is using the same physical hardware and the exact same partitions and logical volumes.

I think this indicates, at least to me, that there are still some bugs in EXT4. I have not however, seen this problem on some of my other systems. Perhaps it is the larger 1.5TB drives I am using on this system.

I hope this helps by preventing you from spending 3 days to discover and resolve this problem.