Tuesday, August 30, 2016

My Annual Love Letter to SchoolTool

It is the end of August, and time once again for me to setup my SchoolTool instance for the coming school year. Each year for the last several years, I have sent an email to the SchoolTool mailing list expressing both my joy and my deep felt gratitude at the pleasure I experienced setting up my very own student information system (SIS).  Sadly, we may have come to the end of an era, and SchoolTool's days may be numbered, so I felt it more appropriate this year to express my gratitude here in my blog.

The reason I feel compelled to write a "love letter" to the SchoolTool developers each year is that they have made the very complex process of setting up an SIS smooth and painless, both by the design of the software itself, and by the wonderful SchoolTool Book written by English teacher and former project manager, Tom Hoffman.  It provides a model of what technical documentation should be, and the influence that the documentation process and the user interface design process had on each other is apparent. With nothing more than the book to guide me, I can create a school year, populate it with courses, sections, terms, time tables, instructors, students, and skills. In just a few minutes I am ready to start the new school year. The ease with which everything works is a total thrill!

I teach dual-enrolled high school / community college classes in a career and technical school in Arlington, Virginia. The SIS provided by Arlington Public Schools is not setup to properly handle the odd configurations of overlapping high school and college classes that I need to make my CS / IT program work.  SchoolTool provides me with a customizable SIS that meets my needs, while providing a host of added benefits to my students.  The CanDo Skills Tracking system lets students see their progress on the explicit skills they are expected to acquire in my classes. The SchoolTool Quiz component enables me to create custom tests and quizzes automatically linked to the skills tracking system.

SchoolTool will forever epitomize what free software means to me and why I've dedicated much of my energy over the past 20+ years fighting for software freedom. It was created in an open process with input throughout by the real users of the system.  I became one of those users back in the Summer of 2005, when I met Tom Hoffman at Pycon and began the collaboration that continues to this day. Both the CanDo and Quiz components were added at the initiative of a small group of us in Virginia, and students of mine contributed directly to the development of both components. There is still no other software, either free or proprietary, that does what SchoolTool does.

The development of SchoolTool was driven by the desire to provide use value and to create a tool to help change the world, specifically by positively impacting education in Africa and the developing world. Thanks to the sponsorship of Mark Shuttleworth, it was freed from the imperative of commodification for an extended period of time. It never could have developed the innovations it has otherwise.

Some big mistakes where certainly made along the way to SchoolTool's development, the biggest of which is probably building SchoolTool on a dead end web application framework, Zope 3, which has now isolated SchoolTool from the larger free software development community. That mistake may cause SchoolTool to follow its framework into abandonment. You never can tell with free software projects, however, since they can be taken up by anyone at any time who finds them useful.  Perhaps SchoolTool will find new life in some unexpected way, or perhaps some of its innovations will find their way into another free software SIS.

I am just happy that it will be available for at least the next several years on Ubuntu servers.  I plan to keep using it for as long as I can, since it is a tremendously effective resource to help my students monitor their learning, and since I get to experience the joy and excitement each year of setting it up!

Tuesday, July 19, 2016

Setting Up a RHCSA Practice Laptop - Part 1

In order to practice for the RHCSA at home, I took an old Dell Latitude E6500 with 4GiB of RAM and purchased a 500GiB hard drive on which I could install CentOS 7 with a server GUI as the base operating system and them multiple virtual machines using KVM with which to experiment and learn.

My package selection for the install was a Server GUI installation. I partitioned the hard drive with 1 GiB of swap, 500 MiB on a standard partition for the /boot, and 30 GiB for the root partition.

I also created a 60 GiB partition for /home, and then allocated everything that remained (375.27 GiB) to /var.  The reason for giving some much space to /var is that the default KVM / qemu setup on CentOS 7 places virtual hard drive images in /var/lib/libvirt/images, so I wanted plenty of space available for multiple images.

After the install finished I wanted to see what the partitions looked like, so I ran
$ sudo yum install system-storage-manager
and then
$ sudo ssm list
which revealed the following:

-----------------------------------------------------------------
Device        Free       Used      Total  Pool        Mount point
-----------------------------------------------------------------
/dev/sda                       465.76 GB              PARTITIONED
/dev/sda1                      500.00 MB              /boot
/dev/sda2  0.00 KB  465.27 GB  465.27 GB  centos
-----------------------------------------------------------------
--------------------------------------------------------
Pool    Type  Devices     Free       Used      Total
----------------------------------------------------
centos  lvm   1        0.00 KB  465.27 GB  465.27 GB
----------------------------------------------------
--------------------------------------------------------------------------------
Volume           Pool   Vol size  FS   FS size    Free      Type   Mount point
--------------------------------------------------------------------------------
/dev/centos/swap centos 1.00 GB                             linear
/dev/centos/root centos 30.00 GB  xfs  29.99  GB  26.73 GB  linear /
/dev/centos/home centos 60.00 GB  ext4 60.00  GB  55.88 GB  linear /home
/dev/centos/var  centos 374.27 GB ext4 374.27 GB 349.02 GB  linear /var
/dev/sda1               500.00 MB xfs  493.73 MB  293.59 MB part   /boot
--------------------------------------------------------------------------------                                                                          

To be continued in Fall of 2016..

Resources

Sunday, April 17, 2016

Moving an ArcGIS File Geodatabase to QGIS

I am taking GGS 553: Geographic Information System this semester at part of my graduate studies at George Mason University.  In a previous post I described how I ended up in this Geographic Information Science graduate certificate program, which I have now been pursuing for almost 2 years.  GGS 553 is a required course, and the first one in the program that has required me to use proprietary software, since much of the course is focused on learning to use ArcGIS.

I am both philosophically and ethically opposed to proprietary software, since it runs dead against the expansion of our shared cultural space, which I believe is vital to the survival of our species. This is a required course, however, and in the large scheme of things I am willing to compromise when I need to. I like to think of it as dancing with the devil, learning the devil's moves in order to be able to freely out dance him in the future. In this case that will mean applying what I learn in GGS 553 to mastering QGIS, the free software alternative to ArcGIS. I had intended to try to do each of our assigned labs this semester in both ArcGIS and QGIS, but when I found it difficult enough just to complete them on time in ArcGIS, I gave up on that idea after the first week.

This week we have a sort of half size assignment, so I thought I would use the extra time available to see if I could do it in QGIS.  The first challenge will be to load the project data into QGIS.  We were given the data in ArcGIS's file geodatabase format. QGIS can not yet read and write to this format directly, but there are tools available to convert it into PostGIS, with which QGIS can work well.

Last Summer I wrote a blog post documenting how I setup a PostGIS server on Ubuntu 14.04.  Since this year I am also needing to learn RHEL, I'll use this guide to setup the server on the little Centos 7 server I have at home for just such purposes, and then connect to it from QGIS running on my Ubuntu desktop.

Installing a PostGIS Server on Centos 7

$ sudo yum install postgis postgresql-server postgresql-contrib
$ sudo postgresql-setup initdb
$ sudo -i -u postgres
$ psql
postgres=# \password postgres
Enter new password: 
Enter it again: 
postgres=# \q
$ exit
$ sudo vi /var/lib/pgsql/data/pg_hba.conf

Change this line (near the bottom):

host    all             all             127.0.0.1/32            ident

to this:

host    all             all             0.0.0.0/0               md5

Next allow database connections from outside:

$ sudo vi /var/lib/pgsql/data/postgresql.conf

Change:

#listen_addresses = 'localhost'

to this:

listen_addresses = '*'

Create a new database user with superuser privileges:

$ sudo su - postgres
$ createuser --superuser [user]
$ psql -c "ALTER ROLE [user] PASSWORD '[password]'"
$ exit

Then as that user create the database and add gis extensions:

$ createdb webster
$ psql -d webster -c 'CREATE EXTENSION postgis'

Then after copying over the Webster.db directory containing the file geodatabase, I ran:

$ ogr2ogr -f "PostgreSQL" PG:"dbname=webster user=[user] password=[password]" Webster.gdb

After which I connected my desktop QGIS to the PostgreSQL server running on my little household server and loaded the three layers I found there:

Resources

Thursday, March 31, 2016

Software Management with YUM

YUM (Yellowdog Updater, Modified) is the package management tool used on Red Hat Enterprise Linux and its derived versions, CentOS and Scientific Linux. It acts as a front end to the RPM Package Manager (RPM), and is used to install, remove, and update software on Red Hat based systems.

I first encountered YUM when installing Yellow Dog Linux on PowerPC based Macintosh computers back at the dawn of the 21st century.  When I switched over to Debian based GNU/Linux systems with the release of Ubuntu in 2004, I completely lost touch with the RPM world until my Spring semester Linux System Administration course's pursuit of RHCSA certification brought me back into the fold.

I am writing this post to use as a handy list of the most common things I need to do when managing software:
  1. Update the software on the system
    $ yum check-update
    $ sudo yum update package_name
    $ sudo yum update [to update all packages]
    $ sudo yum group update group_name
    
  2. List all the currently installed software
    $ yum list installed
    $ yum list installed "global expression"
    
  3. Search for available packages
    $ yum list available "global expression"
    $ yum search term...
    
  4. Display information about a package
    $ yum info package_name
    
  5. Install a new package
    $ sudo yum install package_name
    
  6. Remove an existing package
    $ sudo yum remove package_name
    
  7. List the current repos
    $ yum repolist
    $ yum repolist -v
    
That covers the basics. I also need to learn how to clean up the cruft that accumulates over time as a system is run, in Debian land the kind of thing that would be done with $ sudo apt-get autoremove. It seems that in RPM space that is accomplished with the package-cleanup utility, so I'll look into that.

Resources

Saturday, March 19, 2016

Centos Command-line Tricks and Tips - Getting Rid of the Terminal Beep

Getting Rid of the Terminal Beep:

My terminal was making an annoying beeping (more like a swoosh beep, actually) every time it couldn't match a tab completion.  I like to listen to music while I work, so this was really driving me crazy.  All I needed to do to stop it was to run:
$ echo 'set bell-style none' >> ~/.inputrc
which appends 'set bell-style none' to the .inputrc file in my home directory.  .inputrc didn't exist in my home directory (I checked before running the command), so running this command created it.
After exiting the terminal and starting another, the terminal maintained the silence I wanted it to ;-)

Friday, February 19, 2016

Setting Up a Centos Router - Part 1


In order to run the kind of experiments we will need to run to really learn proper GNU/Linux system administration, we need our own "safe space" in which to play.  In previous years when I had students with the level of skills our ITN 170 group is quickly acquiring, I always used one of our machines as a NAT Router so that we could isolate our own network traffic and setup custom services within our private network space.

The basic idea is captured in the following illustration.
What is required is a machine with two NICs (represented here by Tux) - one which connects to the outside network and the other which connects to the local network.

Setup Process

Here is what I did to setup a basic router using an old desktop PC:

  • Did a minimal install of CentOS 7 on a machine with two NICs, connecting one of the NICs to the outside network and activating this connection using DHCP on the host network during the installation process.
  • Ran yum update after installation to make sure I had the current software.
  • Ran yum install yum-utils vim to get vim and the package-cleanup utility. I then ran package-cleanup --oldkernels --count=1 to remove all but the current kernel package.
  • I ran ip addr and got back information on three network interfaces:
    1. lo - the loopback interface or localhost, with its 127.0.0.1/8 network address.
    2. enp0s25 - the NIC on the motherboard which I had activated with DHCP during installation.
    3. enp3s0 - the addon NIC that was not configured during installation. It had the following information:
      enp3s0:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
          link/ether 00:15:17:20:b6:e6 brd ff:ff:ff:ff:ff:ff
      
  • I edited /etc/sysconfig/network-scripts/ifcfg-enp3s0 adding the following:
    TYPE="Ethernet"
    BOOTPROTO="static"
    IPADDR="192.168.114.1"
    NETMASK="255.255.255.0"
    GATEWAY="x.x.x.x"  (place your gateway adress here)
    
I used the resources linked below to try to enable IP routing and NAT, but I was not successful in getting it to route.  I have a laptop running Centos 7 connected to the router machine.  Before attempting this setup I had installed ClearOS on the router and got it to route for the laptop with a setup process using ClearOS's web interface.  An experienced friend of mine shamed me into removing this, however, by telling me he would never hire a sysadmin who only new how to set this up using a web interface.

So for now I have assigned two of my students to continue looking into it, and I'll get together with that friend who shamed me into this to get his assistance on Tuesday if we haven't figured it out by then.

To be continued...

Resources

Monday, February 8, 2016

Text Processing and Unix History

Preparing for the RHCSA certification is turning out to be a heap of fun! Despite more than 20 years as a free software activist and personal user of GNU/Linux systems for all my personal computing, and despite being a computer science teacher during that same time, there are a wide range of basic Unix CLI skills that I only scratched the surface of in all that time (shame on me!).

Preparing for the RHCSA is providing the opportunity to address that deficit at long last.  Chapter 4 of the book we are using in class to study for the certification is titled "Working with Text Files". The most enjoyable thing about this investigation into Unix text file processing is the view it provides into Unix history.

In the beginning there was eded begat ex, and ex begat vi... Along the way we got cousins grep and sed too.  Since grep, sed, and vi are part of the Unix admin's toolset, I want to learn to use them at least well enough to be able to help prepare students (and myself) for the RHCSA certification and to be able to present them well to future students in my ITN 170: Linux System Administration class.

Since in the beginning there was ed, let me start with that.  I found a very nice blog post, Actually using ed, which I found to be a wonderful introduction to this tool.  I set myself the task of using ed to create a list of fruits in a file named fruits.txt.  The first thing I found out was that trying:
$ ed fruits.txt
did not create the file for me, instead returning a "No such file or directory" error.  So I did the following, which worked:
$ touch fruits.txt
$ ed fruits.txt
0
a
apples
bananas
pears
apricots
kiwis
blueberries
oranges
peaches
cranberries
blackberries
pinapples
teaberries
.
w
110
q
$
After that, I ran $ cat fruits.txt, and saw that everything was as I wanted it:
apples
bananas
pears
apricots
kiwis
blueberries
oranges
peaches
cranberries
blackberries
pinapples
teaberries
Now if I want an alphabetical listing of the fruits in my list, I can run:
$ grep berries fruits.txt | sort
and see this:
blackberries
blueberries
cranberries
teaberries
RegexOne is a nice, interactive tutorial for learning basic regular expressions.  I wanted to do all the exercises using grep on the command-line as well, and in the process setup a new github repo for resources related to our RHCSA study, here.

Next I wanted to learn sed.  Sed - An Introduction and Tutorial by Bruce Barnett is a wonderful tutorial.  With so much awful document out there, it is great to find something written by someone with a grasp of how people actually learn.

Using the fruits.txt file I created with ed, I ran $ sed s/berries/cherries/ fruits.txt and got:
apples
bananas
pears
apricots
kiwis
bluecherries
oranges
peaches
crancherries
blackcherries
pinapples
teacherries
Since sed uses the same substitution syntax that vim uses, learning it will be a big help in becoming a more effective vim user as well.