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This site is a collection of my own work with Linux. Certain things are easy, others take time to decipher and if I ever need to repeat the work (which usually happens!), then I need to remember everything by memory or... have a site with all the steps taken and to take again.

The following are my most recent posts:

Display a line number in a table (i.e. subform of records)

I was ask by a customer to add line numbers to each entry in a table shown in an invoice.

The concept is pretty simple, but really, how do you do that properly in MS-Access?

Microsoft actually has a solution (see link below) and it comes down to writing a function that counts the number of items from that item's current position to the beginning of the table (i.e. going backward). It works, it is just really bad if you have very large invoices since it will tend to slow down as you start getting many items.

There is the function, we can see the counting in the do until near the end ...

As I was working on a MS-Windows installation, I ran in this weird error: Data source not found and no default driver specified...

This was output when I was running the following in a command line prompt:

osql -E

The result should have been an MSSQL prompt instead!

The problem on the computer was that I uninstalled MSSQL 2005 that was automatically installed by Visual Studio C++ and was not compatible with our application, so I first uninstalled that but that uninstallation is really not proper. It leaves a LOT of things behind.

After that I installed MSSQL 2014 which was reported as ...

Installing / Upgrading SugarCRM

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Installing SugarCRM is generally easy, but if you don't want to just make everything writable by Apache, you may find it tricky, especially if you have problems setting up the system.

First of all, you want to get the code from SourceForget.net and extract it in the root directory of the website where you want to use it. I prefer to dedicate a sub-domain name such as crm.m2osw.com to make use of SugarCRM. That way I don't have to deal with other weird things of using this under a sub-directory.

Once in there, the user and group should be a user other than ...

As I am working on my as2js compiler, I stumble on a couple of problems with the for() loop parsing because of the in keyword. That made me think and the for() statement was actually a very funny one. Yes! You can actually write something like this and it compiles:

int zero;
for(3;2;1) zero;

As you can see, all 3 entries in the for() statement are valid expressions and therefore the compiler can compile that code. This creates a loop that runs forever, similar to:

for(;;) zero;

but much less clear to read, obviously.

Now that's food for thought, isn't it?

In JavaScript, you ...

List ciphers currently used by Apache2

If you are using Apache and e-Commerce, you probably want to know all the details of the ciphers used by the Apache SSL module.

So listing Apache supported ciphers is done using nmap as follow:

nmap --script ssl-cert,ssl-enum-ciphers -p 443 secure.m2osw.com

This call gives you a complete list of all the ciphers currently accepted by your running version of Apache. For example, the list may look like this:

| ssl-enum-ciphers:
|   SSLv3:
|     ciphers:
|       TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA - strong
|       TLS_DHE_RSA_WITH_AES_128_CBC_SHA - strong
|       ...

When I lose the Gnome settings...

Now a day, I very often lose my Gnome settings. Most of it, I couldn't care less, but a few things are very important, especially the way my windows work: I HATE it when a window comes to the front when clicked on. It is totally crazy to work that way. Gnome supports the normal X11 way but they don't use that as the default, which is sad.

So I wrote a little script in order to be able to reset my settings without having to open CCSM (the Gnome preference tool) although if you have a hard time finding what you are looking for, CCSM can be useful!

There is my current script that fixes ...

Repair a Cassandra Cluster

I use the Cassandra database cluster system to manage a new set of websites and once in a while I start getting many errors and the website stops working altogether.

When that happens, it is likely that Cassandra broke something in the temporary tables that it holds. The only way to go past that problem is to clear those tables. Until then, it will fail over and over again (they really would need some euristic to auto-clean up even if it means that you're losing some data.)

The command to repair the database, really quick, is as follow:

nodetool scrub snap_websites files

Note that ...

Today I noticed many errors on one of my websites. Looking closer into it, I noticed that the code for the mo_references Drupal module stopped working.

It took me some time, especially because the code seemed to work just fine as all the files could easily be displayed.

Actually, that was not the case. The unpack() character 'a', which I used, was transformed from a simple string that gets trimmed, to all the characters, including the NULL characters. Ouch! Now we have to use the 'Z' character instead.

I use it to unpack() a tar file by loading 512 bytes of data in a ...

#PCDATA and DTDs

Foggy error reports when dealing with #PCDATA in a DTD.

If you are like me and write DTDs to check your XML files to make sure you don't have too many mistakes in them, then you probably have had this problem before.

The #PCDATA has a very special behavior and it is really restrained as follow:

#PCDATA must appear at the start
#PCDATA must be repeated from zero to infinity, so only * work with it
#PCDATA cannot be used with sub-groups (things between parenthesis)

Something like this:

<!ELEMENT Z (P | (#PCDATA | A | B | C)* | Q)+>

does not work because you use + and #PCDATA is within a sub-group.

What you ...

As we are working on a new website, we had a problem where a redirect would not work. I tried both: a simple Redirect and a RedirectMatch as follow:

Redirect / http://finball.m2osw.com/
RedirectMatch permanent ^(.*)$ http://finball.m2osw.com$1

Both of these entries would not work at all.

I verified, to make sure, that the alias module was turned on. It was.

ls -l /var/apache2/mods-enabled

This did list the alias.conf and alias.load entries as expected.

So? What else?

Well... This was installed on a new server and we left the default entry in there:

ls -l ...

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