So I figured I’d try packaging and a couple of hours later and I’ve a copy in my PPA. I’m unsure who maintains the packaging guide so I wanted to say thank you on Ubuntu Planet hoping those involved see it. Its great when you want to try something, find comprehensive instructions and can wrap it up in a few hours.

COmmon Business Oriented Language (COBOL) 85 standard was the first language I was taught. Napier University was a feeder into the banking and insurance industries in Edinburgh at the time and they had sizeable COBOL farms. It proved profitable too, as a number of students I knew went to the US to alleviate Y2K bugs in thousands of legacy applications. COBOL had fallen out of favour in US colleges.

I was talking to someone the other day who mentioned that he maintains COBOL legacy applications. Apparently things have gone full circle for the UK, where COBOL is no longer taught so his company outsources to India. I’m not overly surprised COBOL is dying out as an educational tool because as languages go its not like much else – Dijkstra certainly didn’t rate it:

The use of COBOL cripples the mind; its teaching should, therefore, be regarded as a criminal offence.

Who am I to argue with the man who killed the goto statement? Certainly as a language it has issues – the 86 standard wasn’t totally compatible with the previous 74 standard; it has no functions; and it has no pointers. Then again it was in part based around the work of Rear Admiral Grace Hopper, the coolest woman ever in computer science, so it couldn’t be all bad could it? She believed that programming languages in mathematical notation were generally not well understood – COBOL is about as self documenting as it gets. It is a product of its time – for example the first six columns are reserved for sequence numbers, this came about as forms were used to write programs which were in turn converted to punch cards.

An example is the best way to explain this, so I decided to revisit Project Euler’s first problem and code it in COBOL, something I haven’t touched in years. As Rear Admiral Grace Hopper said:

It’s easier to ask for forgiveness than it is to get permission.

Of course we need a compiler, Ubuntu has Open COBOL available:

sudo apt-get install open-cobol

Lets consider the problem again:

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.

Find the sum of all the multiples of 3 or 5 below 1000.

My solution is to iterate through every number from 1 to 1000, test if it divides by 3 or 5 without a remainder and if so then add it to a counter. In pseudocode:

For counter = 1 to 1000 Step 1
    If counter % 3 = 0 or number % 5 = 0 Then
        total = total + counter
    End If
End For
Display total

But wait – this is COBOL, a language that doesn’t include the word “terse”. So let’s adapt this to a more verbose piece of pseudocode:

For counter = 1 To 1000
    If counter % 3 = 0 Then
        Set flag To TRUE
    End If
    If counter % 5 = 0 Then
        Set flag To TRUE
    End If
    If flag = TRUE Then
        total = total + counter
        Set flag To FALSE
    End If
    Display total
End For

Right, here we go. Its been a long time.  COBOL is organised into divisions, sections, paragraphs, sentences and statements – all are terminated by a period. There are four divisions:

• Identification. Unsurprisingly contains information about the program.
• Environment. This isn’t initially obvious but is concerned with portability – this section allows you to isolate anything that is platform specific. So in theory only the environment division needs changing between platforms.
• Data. This holds all the variables and has four sections – file (file handling); linkage (used with sub-routines); report (for report writers); and the one you almost always need, working-storage (where all your working variables are).
• Procedure. Guess what? Yes this is where the program itself is.

        IDENTIFICATION DIVISION.
        PROGRAM-ID. EULER_PROBLEM_ONE.

Not much explanation required there then. We don’t need an environment division, it doesn’t hurt to populate the division name anyway.

The next division requires a little more explanation. We need a working-storage section but COBOL defines variables using level, name, picture clause and optionally a value.

Picture clauses define a variable’s format. Levels allow data to be grouped, for example if you defined a student as having an ID and a name you might have:

01 student.
    02 identifier          PIC A9(7).
    02 name                PIC A(30).

Level numbers are for the most part arbitrary as long as the lower the number the higher the level, with the exception of 66 (deprecated), 77 (individual elements) and 88 (used to define conditions). Picture clauses can use: 9 (digit); A (letter); X (digit or letter); V (decimal point); S (sign). You can use A(30) rather than typing loads of A’s.

That just leaves us a procedure division. If you have ever coded assembler then you’ll probably find this easier than if you’ve used C. You need to describe every step. The main iteration construct we need from our pseudocode is a For Loop. COBOL has a PERFORM statement, you need to increment your counter yourself:

PERFORM UNTIL counter = 3
    ADD 1 TO counter GIVING counter
END-PERFORM.

A general convention is to use upper-case for reserved words and lower-case for variables. Pretty much all operations follow this command’s format – do something (ADD 1) to something (counter) and store it somewhere (counter).

IF condition1 > condition2 THEN
   STATEMENT
ELSE
   STATEMENT
END-IF.

You can nest if statements (there’s no Else If statement). Its not uncommon to find a lot of legacy code that only uses IF statements, why I don’t know because it has a Case statement called EVALUATE.

That just leaves us assignment:

MOVE value TO variable

Putting it all together, you need variables to Hold temporary values used to calculate answers, I always call it junk:

        IDENTIFICATION DIVISION.
        PROGRAM-ID. EULER_PROBLEM_ONE.

        ENVIRONMENT DIVISION.

        DATA DIVISION.
        WORKING-STORAGE SECTION.
        01 total        PIC 999999     VALUE 0.
        01 counter      PIC 9999       VALUE 1.
        01 junk         PIC 999999     VALUE 0.
        01 flag         PIC 9          VALUE 0.

        PROCEDURE DIVISION.
        PERFORM UNTIL counter = 1000
             COMPUTE junk = FUNCTION MOD (counter, 3)
             IF junk = 0 THEN
                 MOVE 1 TO flag
             END-IF
             COMPUTE junk = FUNCTION MOD (counter, 5)
             IF junk = 0 THEN
                MOVE 1 TO flag
             END-IF
             IF flag = 1 THEN
                ADD counter TO total GIVING total
                MOVE 0 TO flag
             END-IF
             ADD 1 TO counter GIVING counter
        END-PERFORM.
        DISPLAY total.
        STOP RUN.

Remember that indentation is important (despite the code formatting here not wanting to do it) – areas A and B take the first 6 characters so you need to begin in column 7.

Save the file as euler.cob, compile and run it:

cobc -x euler.cob
./euler

Giving the correct answer of 233168, albeit without any frills.

Hold on to your hats...

It took me a while to get this to compile – Open COBOL doesn’t care for the AUTHOR statement in the IDENTIFICATION DIVISION so I removed it.

What this snippet of code doesn’t show us is that larger projects are unbelievably verbose, lines and lines of code. Nor does it cover the hilarity of design using Data Flow Diagrams - queuing for hours to collect printouts from the University’s only 132 column printer.

Well that’s been a fun trip down memory lane, I don’t remember why I started this post.

Now get off my lawn.

Linux
If you’re using Linux, you’re probably a geek and don’t need some guy who blogs about manliness to tell you how to edit your host file.

I bought a new one (surprised that the hard disk size going up seems to have reduced any price decreases over time).

Seems like a faulty fan – sounds like a bearing grinding. Anyone any experience with them?

That doesn’t really bother me. The customer support agent told me to use BT’s speed diagnostic tool. Now aside from why their tool would be better, its not really an option as its a poorly written Java applet that doesn’t seem to work with Firefox or Chromium in Linux. Now I dare say I could get it to work but why spend the energy? When I mentioned it to the agent, he told me BT doesn’t officially support Linux and helpfully suggested I keep a Windows laptop handy.

Are you kidding? Keep a Windows laptop handy? There are reasons why I use Linux, there are reasons people use Macs and Windows too – they chose to. What the hell has that got to do with my ISP? I have no software from them, it’s a wireless access point they provide. Do you know what operating system it runs? Linux.

The page explains what to do but in synopsis, you need to add the repository and install two packages, obviously check out the site before blindly following me:

Add the repository to /etc/apt/sources.list:

deb http://www.bchemnet.com/suldr/ debian extra

Now, I know Ubuntu has the apt-add-repository command, however it will create a source entry too, which will give you an error:

W: Failed to fetch http://www.bchemnet.com/suldr/dists/debian/Release
Unable to find expected entry  extra/source/Sources in Meta-index file
(malformed Release file?)

If you did then you need to remove the offending deb-src http://www.bchemnet.com/suldr/ debian extra entry.

That done, add the GPG key and update the apt cache.

wget -O - http://www.bchemnet.com/suldr/suldr.gpg | sudo apt-key add -
sudo apt-get update
sudo apt-get install samsungmfp-driver samsungmfp-data

It will then pick up and install when you plug it in. Samsung themselves provide a 30 odd Mb driver file, here. There are a whole list of the differences here but for me, I prefer Debian compliance and not installing anything I don’t need.

Oh and a big thank you to everyone who sent me suggestions of what to do in San Diego. People can be surprisingly open and friendly – especially within our community.

Still, it was more productive than my week with my Open University module that starts in October – T175 (Networked living: exploring information and communication technologies). The OU can be very Windows dependent but this course seems to be pretty much delivered in Virtual Learning Environment (what the OU calls Moodle). I ran the course DVD, which is a Windows Flash standalone thing which got me to revive the OU Ubuntu Users group, sending out emails, starting a mailing list and trying to get things going again.

So why was it unproductive? Well, I haven’t booted Windows in ages – there were a million updates, one of which was for the wireless driver. Update completely borked the wireless and I wound up restoring the drive. That aside, one thing I really like about Ubuntu (and most distributions) is a centralised update manager – Windows has Adobe, Java, Windows Update, Firefox and McAfee all trying to pull updates at the same time. It makes the system completely unusable for the first ten minutes it’s on!

Any way, I decided to build a new WordPress theme. Same colour scheme, more rounded edges – should be available in the next few days.

Edit ~/.vimrc or /etc/vim/vimrc (for system wide) and add turn off vi compatibility:

set nocompatible

The latter can be improved by editing ~/.inputrc (or /etc/inputrc for everyone). Pressing the up key scrolls through all the commands you’ve typed but by adding:

"\e[A":history-search-backward
"\e[B":history-search-forward

You can type the first letter or two and get the command you need, so if you typed “mysql -u root -p” last Tuesday but can’t remember the options, typing “my” and pressing the up key will find it.

Synaptic (System→Administration→Synaptic Package Manager) lets you install common groups of packages (Edit->Mark packages by task…) in this case a LAMP server. You can do the same from a command line using “sudo tasksel install lamp-server“. Since Ubuntu 10.10, you need to install tasksel to install by task either way – “sudo apt-get install tasksel”.

Once the components are installed, you’ll be asked for a root password – this is used by MySQL and is not the system’s root password.

The default web root is /var/www – if you check it now there is an index.html. Open a browser and goto http://localhost, you’ll be greeted with the contents of that file so we know the system is working. So how do we get our own files up?

You need to consider permissions, this is the casue of “Forbidden/You don’t have permission to access / on this server” error messages . There are a couple of ways but I recommend using the www-data group. You could use a folder in your home folder, however I have never got this will not work with encrypted home folders. I would leave /var/www in root’s ownership and add each subsite as belonging to www-data then give that group write access:

sudo mkdir /var/www/wordpress; sudo chown :www-data wordpress; sudo chmod g+w wordpress

The first user will have been added to this group during installation (you may need to logout) but further users can be added using System→Administration→Users and Groups or by:

sudo useradd -G www-data username

Apache uses virtual hosts – multiple sites on the same server. Each site is defined by a configuration file in /etc/apache2/sites-available. If you look there now, you’ll see the default site, we can use this as a template for a new site:

sudo cp /etc/apache2/sites-available/default /etc/apache2/sites-available/wordpress
gksu gedit /etc/apache2/sites-available/wordpress

You need to add a ServerName, change the VirtualHost, DocumentRoot and Directory to point to the folder your site is going to be in, changes are in red.
<VirtualHost wordpress:80>
ServerAdmin webmaster@localhost
ServerName wordpress
DocumentRoot /var/www/wordpress
<Directory />
Options FollowSymLinks
AllowOverride None
</Directory>
<Directory /var/www/wordpress>
Options Indexes FollowSymLinks MultiViews
AllowOverride None
Order allow,deny
allow from all
</Directory>
ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
<Directory "/usr/lib/cgi-bin">
AllowOverride None
Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
Order allow,deny
Allow from all
</Directory>
ErrorLog ${APACHE_LOG_DIR}/error.log
# Possible values include: debug, info, notice, warn, error, crit,
# alert, emerg.
LogLevel warn
CustomLog ${APACHE_LOG_DIR}/access.log combined
Alias /doc/ "/usr/share/doc/"
<Directory "/usr/share/doc/">
Options Indexes MultiViews FollowSymLinks
AllowOverride None
Order deny,allow
Deny from all
Allow from 127.0.0.0/255.0.0.0 ::1/128
</Directory>
</VirtualHost>
You can then add “wordpress” to /etc/hosts (change the line that reads 127.0.0.1 localhost to 127.0.0.1 localhost wordpress) and use the address “http://wordpress” to access your site.

Apache needs to know about the site:

sudo a2ensite wordpress; sudo /etc/init.d/apache2 reload

Now with the letter “A” out of the way we can deal with the “M”. Most web applications need at least one database. Remember that MySQL password?

mysql -u root -p

A good example is installing WordPress. Download and extract the contents to /var/www/wordpress – remember the wordpress folder already exists so put the contents in there. Create a new database called “wordpress“, with a user called “wordpress” and a password of “wordpress” by entering each command at the prompt:

create database wordpress;
grant usage on wordpress.* to wordpress@localhost identified by 'wordpress';
grant all privileges on wordpress.* to wordpress@localhost;

Type “\q” to exit then open a browser and go to your site, for me that’s http://localhost/dougie.

So lastly we get on to the “P” – PHP. Apache will recognise and run PHP, however be aware of a caveat I’ve noticed in Ubuntu. If you try to use your system hostname instead of localhost in Firefox, it will try to download rather than run PHP files. I believe this is due to the system hostname resolving to 127.0.1.1, a solution to Debian bug #316099.

PHP applications often have their own installation scripts, which WordPress does. Enter the database details we just created on the WordPress install screen:

Once the rest of the screens are complete, you’ll have WordPress installed.

So to summarise:

1. Install a LAMP stack – sudo tasksel install lamp-server
2. Create a folder and set the correct permissions – sudo mkdir /var/www/wordpress; sudo chown :www-data wordpress; sudo chmod g+w wordpress
3. Download WordPress and put the contents in /var/www/wordpress
4. Open mysql:mysql -u root -p
5. Set up database: create database wordpress; grant usage on wordpress.* to wordpress@localhost identified by 'wordpress'; grant all privileges on wordpress.* to wordpress@localhost; \q
6. Run http://wordpress/install.php

So to recap, all we need to do to add an application is create a virtual host so Apache can serve it up; create a database for it to store data; and configure the application – often via a browser interface. Now you can hack away at those WordPress themes to your heart’s content.

More information is available from the Ubuntu Server Guide.