JC Web Concepts - Custom Web Developments

I was asked to write my experiences when using Parallels on my Mac. So I thought I would make a blog post about this at the same time to share my thoughts on this topic. If you own a Mac, Parallels is a purchase that is a must. It makes your life easier. So let me get onto my experiences.

Windows at work

At my work most computers are running Windows XP. When I decided to use a Mac instead of a Windows computers, I came into some issues. There are tools that only have Windows applications and I thought I would be in trouble. I ended up installing XP in Parallels and I was able to install the applications I needed. I needed access to internet explorer to run my automation scripts against website in internet explorer. The company runs some web applications that will only work in internet explorer and Parallels run these applications seamlessly. No issues at all, I do not even know that I am running a virtual machine.

Linux servers

Another thing that Parallels help me with is being able to setup Linux virtual machines. I create a lot of how-to tutorials and I use these virtual machines for them. Installing Linux in Parallels is easy and I do not run into many issues. Setting up and compiling kernels are easy to do. My Gentoo and Ubuntu distros find all the parallels drivers and it makes it so much easier.

The bad

The only bad thing I can say is gaming. I do understand that this is not easy but it is getting closer.

Conclusion

I thank the Parallels team and hope you guys and gals keep improving and keep bring in new features for your product.

As a web developer one of the tools that I love to use is built right into the operating system. I have come across some jobs where the coder has coded everything in absolute paths. Let me show you an example of an absolute path and a relative path.

….

Absolute Path
<a href="http://www.jcwebconcepts.com/index.php">Home</a>
 
Relative Path
<a href="index.php">Home</a>

As you can see there is a little difference. So now you may ask why is this an issue. Well if you are like me and like to test stuff on a local server first, then you will run into some issues. If your page calls an file it will call it from the remote server and not the local one. There are other examples but I will spare you of them. Lets get to this hosts file.

The hosts file exists in modern day operating systems. You can find it in Linux, Mac, Unix, and or Windows. Let me show you where these files exist.

Linux (Most distros)/Unix
/etc/hosts
 
Mac
/etc/hosts
 
Windows
C:\Windows\system32\drivers\etc\hosts

Here is an example of what a host file looks like

So now let me show you some magic. So now on your testing box I would add a new entry. It can be added anywhere you want. So add this line

127.0.0.1     http://www.jcwebconcepts.net
127.0.0.1     http://jcwebconcepts.net
127.0.0.1     www.jcwebconcepts.net
127.0.0.1     jcwebconcepts.net

Of course you could substitute with any domain. So now when you test your files/scripts and the point to the absolute path you will pointing to your local box. Of course when you are done I like to comment that out. Just in case I forget that I have that and I want to look at the remote site. Now if you want to see the test environment on another computer the line you add to the host file will be different. First get your IP of the test box. Mine is 192.168.2.120

192.168.2.120     http://www.jcwebconcepts.net
192.168.2.120     http://jcwebconcepts.net
192.168.2.120     www.jcwebconcepts.net
192.168.2.120     jcwebconcepts.net

So you can start to see the things you can do with the hosts file that can help you. Instead of recoding all those absolute paths to relative you can edit the hosts file and test it that way.

Here is a video that explains some of this

When I first learned Linux about 12 years ago I started off using Red Hat. You guys who have used it long enough remember the day when you wanted to install an app you had to not only download the application but 5 or 6 dependencies. In todays world that has changed. Things have been made so much easier. Thru the years I have used different distributions from Red Hat, SuSE, Fedora, Ubuntu, and CentOS. If you have used the Fedora and Red Hat land distro’s then you are not going to have much of a problem.

To do a net install it is not as easy like the other distro’s but if you have seen one version of Linux you have seen them all. The big thing about CentOS that I really like is that apps are tested fast and properly. Updates seem to be coming before some of the other versions of Linux. For now I use CentOS to try to stay on top of it to keep my knowledge up on some of these distributions. So go try and download a copy and throw it in a Virtual environment. See what you think and post a comment if you have a different opinion or question(s).

For the people who do not know what NAS stands for, it stands for Network-attached Storage. Do you have an old computer that is just sitting there collecting dust? I for one when I bought my iMac and MacBook my Dell became a dust collector. So one day I decided I needed to set something up to backup my files. I know I could have burnt stuff to DVD or buy an external hard drive to store them on.

Now for the Mac I could use a portable HD to setup Time Machine. Now my concern with Time Machine is that as far as I know you can only use it for one computer. Now I have not researched it so I could be wrong. With the external if you do run multiple operating systems like Linux or Windows then you have to worry about how you format your HD. Also if you buy a portable that needs a power source then I need to fiddle behind my desk to plug in the power adapter for the HD. What a mess I’ll tell ya.

Now if you have the luxury of having a dual layer burner you could burn all your backup data. Now I will tell you that data that does not change I still put to DVD but why waste it all for stuff that changes. You then need to setup databases or spreadsheets on what stuff is on what DVD or CD. I do not know about you but I would not want to worry about all that stuff.

So this brings me to setting up a NAS server. All you need is a computer with a decent size hard drive and if you want to hide it a wireless card. The other option here is buying a time capsule cause that is basically a NAS server. So if you decide the old computer you then have 2 choices for the OS that I would use. One is FreeNAS which is based off FreeBSD and the other would be Ubuntu. I basically chose Ubuntu cause I can run other things off it like a web server and set it up as a puppet master for some of my virtual machines.

So what are you going to choose? Do you have any opinions on what you think about storage backups? Post a comment and let us know what you believe the is the best backup solution.

Since posting my tutorial on running a web server on Ubuntu 9.10, I have had some questions on some of the next steps. So in this tutorial I want to discuss what you want to do to get your web server on the internet. I want to discuss on how to set it that a standard user can edit files in the web directory.

Are you running a Linux or Unix server that there are process you need to automate? Is there a daily process that are just a waist of your time but not to your server? There is a nice application called Expect that can help you with this. This application can handle several protocols. Some are ssh, telnet, ftp, passwd, fsck, rlogin, tip, etc… This application does not need a server it is just a client. The client is installed where your script will run from. The nice thing about expect is the file can be executed on a webpage as well. So let me show you an example script:

#!/usr/bin/expect
 
###Usage: call the file with a username.
 
spawn ssh -i /var/employee/includes/id_rsa root@10.10.1.12
expect "The authenticity of host '10.10.1.12 (10.10.1.12)' can't be established.
RSA key fingerprint is 47:4a:6a:ce:65:99:e2:93:2b:7t:a9:48:19:64:f6:28.
Are you sure you want to continue connecting (yes/no)?"
send "Yes\r"
expect "root@10.10.1.12's password:"
send "iamthegreatone\r"
expect "#"
send "cd /home\r"
expect "#"
send "rm -Rf $argv\r"
expect "#"
send "cp -a default/ $argv\r"
expect "#"
send "chown -R $argv:513 $argv\r"
expect "#"
send "exit\r"
expect eof

This script is executed by running the following:

root@john-server:~# expect thefilename.exp john

This is a script I use at work to reset my users profiles when they mess them up. As you can see then when you run the file you must pass an argument. So in this case you ssh into the server that has the user directories pass the name of the directory. So this script will remove the current users directory and cp the default profile directory to theirs. It will then set the right permissions for the user. Note: The group 513 may be different from server to server.

Now you do not need to use ssh or anything like that. So if you want to have the script live in the same box you can remove the SSH information. Hope this helps and give it a try it is a nice tool.

If you have been reading previous blog posts, I have been using a monitoring tool called Zenoss. Under the hood there is a lot of Python stuff. So I decided to start learning Python. Python can run on Mac, Linux, Unix, and Windows. Let me show you some basic on what you can do in python.

#!/usr/bin/python
 
firstName = "John"
lastName = "Costanzo"
 
# Lets just print out one variable
print firstName
 
# Now lets complete my name
print firstName, lastName
 
# Lets just print something random without a variable
print "The sun is warm. The grass is green"
 
# Now I will print some variables followed by some text
print firstName, lastName, "Is the owner of this blog."

For more information on Python you can visit this site.

When I first started working with Linux one of the tools I disregarded was VIM. I felt it to be too confusing and believed it was not worth it at all. I was so use too notepad, nano, pico, etc… Then a programmer finally convinced me one day to make a switch. I am so glad I did.

So the first thing you have to get use to is that there are two modes to be in. One is command mode and the other is in insert mode. When in command mode you can save or do other things like find and replace. In insert mode you do like you normally do. You type away. I know it sounds confusing now but wait and I will show you what I mean.

VIM can be found in Mac, Linux, Unix, and or Windows. To start a file you bring up your terminal or if in Windows you open the application in your start menu. In the terminal you will type

vim whateverfilename

In the Windows work you go to file -> new I believe. Sorry not much in the Windows side of things.

Command Mode

Ok so lets get into some of the things you can do in command mode. So lets say you have to edit a document for work and you have to change the word Bob with the word John. hit ESC to make sure you are in command mode and hit the following:

:% s/Bob/John/g

The g at the end will make sure it goes thru the whole document. To search for some text is not that hard to do. So lets say we want to find all instance of the word happy. You will do the following:

/happy

When you find the first result you can hit n on your keyboard to go to the next instance that it finds the work happy. If there is none it will tell you that there is none. Now I am sure you are asking how do I search for multiple words? Well let me show you how to search for Happy Birthday

/Happy Birthday

As you can see you I did the same thing as above. VIM knew that you were looking for multiple words. Before you ask if there is a term in the document called Birthday of Happy, it will not bring that up as a result. The next thing I want to show you is if you need to get to line 10000 in a file all you have to do is the following:

:10000

Yep that is it. To wrap up this first tutorial on VIM I will show you how to quit without saving, saving but not exiting, and saving and exit. Here they are in order.

:q!

The q stands for quit. If you forget the ! you would be prompted about saving before quiting

:w

The w tells VIM that you want to save the changes

:wq

As you see we combined the w and the q to save the changes then quit. Now before you ask, if you would do :qw that would fail. Cause vim reads the commands from left to right. Well I think that is enough for now. If you have any questions about vim please post a comment.

Below is a video on what I basically explained above.

If you are setting up a server that you might want to monitor, you will want to install setup SNMP. In this tutorial we will set it up in Ubuntu 9.10.

One of the things I never understood after installing Zenoss, was where is this mysql database. I found out that with Zenoss it sets up it’s own MySQL server and it is even smart to put it on a different port.
So lets say you want to access this database and see what it looks like. This can be done by doing the following:

SSH into the server that zenoss is on and

su zenoss
mysql -u zenoss -p

Just enter the password for your zenoss database and then you can have access to the MySQL server. Hope this helps out someone.