Topher’s Scribbles

We all know that PHP5 has a lot more OOP features than PHP4, and we all know that it is not a real OOP language. There are a lot of things in PHP5 that won’t work like Java (obviously). With that said, I just want to point out one feature that I noticed while playing with PHP5 classes.

In Java, when you extend a class, it will run the parent’s class constructor first, then it will invoke the subclass’s constructor. Unfortunately in PHP5, when you extend a class, it will NOT invoke the parent class. You will have to manually invoke it yourself using the ‘parent::’ construct. Here’s some code (syntax may be wrong, excuse me, but you get the point):

class Hello
{
    public function __construct()
    {
      echo "Hello";
    }
}

class World extends Hello
{
    public function __construct()
    {
        parent::_construct(); //<-- must do that in order for the output to be "Hello World!";
        echo " World!";
    }
}

$test = new World();
?>

Output above would be..
Hello World!

If you didn’t add the parent::__construct(), output would be..
World!

It took me a while to figure this out. I wanted to deny the public access to a directory, like /deny and allow the public in a subdirectory like /deny/allow.

This was done by the specific order of Allow, Deny. If you mix these up, you will either allow all or deny all. Anyway, here’s what you do to deny users to /deny and allow users in /deny/allow.

<Directory /deny>
Order allow,deny
Allow from insert IP’s
</Directory>

<Directory /deny/allow>
Order deny,allow
Allow from all
</Directory>

Here’s a quick reference for Sendmail users. The commands below are to start, stop, restart, and rebuild aliases for the Sendmail Daemon.

Stopping Sendmail
# cd /etc/mail
# make stop

Starting Sendmail
# cd /etc/mail
# make start

Restarting Sendmail
# cd /etc/mail
# make restart

Rebuild Aliases
# cd /etc/mail
# make

Enable Sendmail on startup
# echo ’sendmail_enable=”YES”‘ >> /etc/rc.conf
# echo ’sendmail_submit_enable=”YES”‘ >> /etc/rc.conf

Disable Sendmail on startup
# echo ’sendmail_enable=”NO”‘ >> /etc/rc.conf
# echo ’sendmail_submit_enable=”NO”‘ >> /etc/rc.conf

Done!!

Here’s a list I have compiled that explains many Bash test operators. This is pretty much all I use. I think there’s more, but I will add to it as I discover them. I’ve been wanting to put this online so I can use as a reference and I finally did. So here it is, enjoy!!

Done!!

I had just recently installed 2 new servers and both of them had PHP dumps (php.core) and issued a segmented fault, signal 11. I installed PHP5 and installed PHP5-Extensions through the ports.

My first experience with the dump, I wrote a simple code to calculate interest rates, which was totally incorrect (my code btw). My second experience, on another server, was when I was installing pear-DB through the ports. It uses PHP to compile and it kept erroring and wouldn’t finish compiling. So I searched Google and found out that when you install PHP extensions via ports, these dumps occur. I am not sure about the exact reason why it dumps, but apparently PHP is very picky as to when the extensions are loaded, or rather the order in which they are loaded.

So my first search landed me to the FreeBSD lists, and there, they said to make sure the sessions module loaded first, or somewhat first. I edited my extensions.ini file (/usr/local/etc/php/extensions.ini) and moved ‘extension=session.so’ to the top of the list. I saved the file, and re-compiled pear-DB, and it still errored. So I researched some more and I was lead to pingle.org. His post mentioned the same extensions order as well, but placing some of the extensions last. He had recode, mysql, imap, sockets, and lastly pspell at the bottom of his list. I did the same and what do you know, no more dumps!! Woo Hoo.

From what people are saying is that when you have this “magic” order of extensions, to save the order because when you upgrade php or the extensions, it will overwrite this file.

Done!!

I’ve been trying to set up a backup file server using FreeBSD 6.2-RELEASE amd64, Areca RAID, and using a partition that is >2TB. My first install crashed the server under heavy writing. I was rsyncing 3 servers simultaneously. Checking the logs, there were some “kernel: g_vfs_done():…Error: 5″ errors before the crash. I searched google and found out that it was a common error on Areca cards using FreeBSD. So I found a solution on the Areca website, http://areca.tw.com, and it said to edit the driver source code. I recompiled the kernel and started over again. This time, I am rsyncing 4 servers simultaneously and updating ALL the ports via cvsup (I had updated them earlier so there was nothing to really update. What I did was remove the ports tree, then I cvsup again). So far, no g_vfs_done errors and no crashes (knock on wood).

Here’s how I installed the server step by step:

1) I have 10×1TB Hitachi HD’s. I created 1 Volume at 100GB using RAID6 and another Volume at approximately 6.3TB using RAID6 as well. Make sure you use LBA 64 for any volume greater than 2TB. You can obviously create your own volumes depending on your usage. However, the 100GB Volume is just for FreeBSD.

2) Install FreeBSD on the first Volume, which should be da0. Do not touch the da1 volume.

3) When that’s done, install all the sources using sysinstall, and navigate to Configure > Distributions > src, and choose ALL.

4) Now we edit the driver. Open up /usr/src/sys/dev/arcmsr/arcmsr.c with any editor. You will see the following if statement at or around line 1304.

if(acb->srboutstandingcount >= ARCMSR_MAX_OUTSTANDING_CMD) {
pccb->ccb_h.status |= CAM_SCSI_BUSY; //<-- REMOVE THIS LINE
arcmsr_srb_complete(srb, 0);
return;
}

All you need to do is remove one line and add 2 more. The new if statement should look like this:

if(acb->srboutstandingcount >= ARCMSR_MAX_OUTSTANDING_CMD) {
pccb->ccb_h.status &= ~CAM_STATUS_MASK; //<-- ADD THIS LINE
pccb->ccb_h.status |= CAM_REQUEUE_REQ; //<-- ADD THIS LINE
arcmsr_srb_complete(srb, 0);
return;
}

5) Recompile the kernel and reboot (I was going to go into detail on the kernel recompile, but I will post this elsewhere).

Hopefully you have no errors up to this point. Now we partition the >2TB filesystem, mount it, and add to the fstab. From this point, I will use my volume set up. Just adjust to your settings if yours are different.

6) We will be using gpt to create a >2TB partition table.

# gpt create -f /dev/da1

7) Next, we add a gpt partition.

# gpt add /dev/da1

You can view the partition by using this:

# gpt show /dev/da1

8 ) Now we format the partition.

# newfs /dev/da1p1

9) Create a folder, let’s just name it /HUGE_STORAGE and then we mount it.

# mkdir /HUGE_STORAGE
# mount /dev/da1p1 /HUGE_STORAGE

10) Finally, we add this to fstab. Open up /etc/fstab and add this line to the bottom.

/dev/da1p1 /HUGE_STORAGE ufs rw 2 2

This exact set up has so far been a success. I will post anything that comes up, good or bad, here. Good luck!!

Done!!

UPDATE: Feb. 21, 2008 

I am happy to say that I have been monitoring this server and haven’t received any errors at all!! It runs about 3 rsyncs simultaneously nightly, and I’ve already tar/gzip’d  a 96GB file, mounted 2 samba mounts (which doesn’t have anything to do with the RAID card or hard drives), and moved/copied/removed/hard linked directories that were approximately 100Gb.

Here’s how I recompiled the kernel. I got this from the FreeBSD Handbook, but I wanted to post for my own notes. If you want more information, please refernence the handbook at FreeBSD.org

1) Before we start, make sure that we install the all the sources. Just go to sysinstall and navigate to Configure > Distributions > src, and choose ALL.

2) The handbook says to either copy the kernel or link it from another location. I chose to link it from the /root directory. Let’s just call the kernel MYKERNEL (ya ya, just like the handbook).

# cd /usr/src/sys/i386/conf
# mkdir /root/kernels
# cp GENERIC /root/kernels/MYKERNEL
# ln -s /root/kernels/MYKERNEL

3) Now we can edit either the kernel or edit any driver source code or modules, like the Areca drivers.

The next step is to compile and install the new kernel, but I wanted to mention this: If all you did was edit a driver, like in my future post, (insert link), and you don’t want to recompile all the modules, then open up /etc/make.conf (or create one) and use MODULES_OVERRIDE. This will only compile the modules or drivers you tell it to. It will definitely make the compile go much faster.

Here’s an example: Say you edited the Areca Driver, and acpi. Your MODULES_OVERRIDE line would look like this:

MODULES_OVERRIDE = acpi arcmsr

One thing to note is that this is all relative to the /usr/src/sys/dev/ directory. So if you wanted to recompile a sound driver and the modules I mentioned above, you would use this:

MODULES_OVERRIDE = acpi arcmsr sound/sound sound/driver/ds1

4) Now we can compile the kernel…

# cd /usr/src
# make buildkernel KERNCONF=MYKERNEL

5) and install it.

# make installkernel KERNCONF=MYKERNEL

And that’s it. Again, please reference the handbook at FreeBSD information.

Done!!

This is kinda old news and pretty much intuitive, but if you have an old FreeBSD system and update your ports, you may receive this error message when you try to install a package:

Easy fix..just add X11BASE=${LOCALBASE} to the /etc/make.conf file like this…

Done!!!

I normally don’t do this for my own personal account, but sometimes you need to use SSH in your scripts. Anyways, here we go:

I will refer to the server that you will access from as ‘Server_Alpha’, this is where the scripts would reside. The server that will be accessed, will be referred to as ‘Server_Beta’. The user wil be named, uhh, ‘User’.
First of all, make sure the user is in both machines. Once that is done, create a folder in your home directory with:

$ mkdir -p /usr/home/User/.ssh

Now to create the key:

You will get a prompt and the output so far should be something like:

Hit Enter, and it will then prompt for a passphrase. Do not use a passphrase. Just hit the enter button twice.

If successful, you will see something like this:

OK, we are done with Server_Alpha. Let’s move on to Server_Beta.

Make sure that a .ssh directory exists in the home directory and copy id_rsa.pub from Server_Alpha to A file named authorized_keys in the .ssh folder.

You can copy and paste, or use ssh. Just make sure that it is only one line!!

Done!!

This is more a rant than anything to do with what I normally post, but I just had to post this!!

In case you don’t know, I am a System Administrator for a web design company and I used to work in Tech Support for a hosting company. Since the beginning, I used dnsstuff.com for all my DNS, domain name, email tests. That site was great up until they require you to register. I was so upset that I purchased my own domain name, dnsyard.com, and started to work on my own “dnsstuff”.

Anyway, I periodically check my google ranking (OK, you got me, more like everyhour!!) and I noticed that I am on page 4 for the keyphrase, “free dns tools” (WOO HOO!!). Of course, dnsstuff ranks number one, but I noticed that the number 2 spot has changed. Well it happened to be freednstools.com. I never noticed them, and I’m sure I would have a while ago, but I decided to check them out.

So I did some snooping around. I checked their source code and first of all, noticed that they weren’t using any Keyword Meta Tags, and they rank 2nd, which doesn’t really bother me because the domain name is pretty much the keyphrase (noticed I didn’t link to them at all in this post? haha). Also, their homepage is exactly how dnsstuff used to be, and it included the same exact tools too. So I did a whois for their domain name on their site. And what do you know… The page returned an error.

WOW!! I guess that’s one way to compete with dnsstuff.com. What more can I say??

BTW, check out my site,  http://dnsyard.com/ (in case you forgot it). I only have a few tools, but I will continue to add to it. Hope you enjoy it.

Done!!