As the title says, not all programs are compiled. Your reaction might be: Gasp “That means that the last post was a lie?” “No”, I would respond. Read on.
There are two kinds of programming languages – ones that are compiled and ones that are interpreted. (Shotts, 2019) The compiled programming languages undergo the process described in the previous post. Interpreted do not. Interpreted programming languagesare executed line-by-line. So instead of taking the whole program and translating it into zeroes and ones, then linking it and forming an executable file, a program called interpreter goes line-by-line over the interpreted language’s source code and executes it as it encounters each line of the source code.
Interpreted languages are generally slower than compiled languages.
Hope you learned something new!
References
Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Pages 375-376
In this article, I will mention a couple of key terms related to the Linux desktop. (Ward, 2014)
The first one is the X Window System. It is just a framework – think of it as “bare bones” of a GUI (Graphical User Interface) environment. It is up to other programs to build upon this “bare bones” and construct the graphical user interface. (“X Window System,” n.d.)
Desktop environment is a package that allows for cooperation of different applications in a graphical sense. For example, application A tells application B that it is 50% done with a certain task and the application B displays that on its status bar. GNOME and Unity are examples of a desktop environment.
Some other terms and their explanations: Window managers arrange windows on the screen and provide interactive decorations like title bars that allow the user to move and minimize windows. Common elements on desktop applications (such as buttons and toolbars) are called widgets. Toolkits are used to provide widgets because that speeds up development.
That’s it for this post. I never dug really deep into Linux desktop, but if you ever encounter any one of these terms, I hope you have some more clarity as to what they mean.
Hope you learned something useful!
References
Ward, B. (2014). How Linux Works: What Every Superuser Should Know (2nd ed.). No Starch Press. Pages 297-299
In this article, I will mention a couple of key terms related to the Linux desktop. (Ward, 2014)
The first one is the X Window System. It is just a framework – think of it as “bare bones” of a GUI (Graphical User Interface) environment. It is up to other programs to build upon this “bare bones” and construct the graphical user interface. (“X Window System,” n.d.)
Desktop environment is a package that allows for cooperation of different applications in a graphical sense. For example, application A tells application B that it is 50% done with a certain task and the application B displays that on its status bar. GNOME and Unity are examples of a desktop environment.
Some other terms and their explanations: Window managers arrange windows on the screen and provide interactive decorations like title bars that allow the user to move and minimize windows. Common elements on desktop applications (such as buttons and toolbars) are called widgets. Toolkits are used to provide widgets because that speeds up development.
That’s it for this post. I never dug really deep into Linux desktop, but if you ever encounter any one of these terms, I hope you have some more clarity as to what they mean.
Hope you learned something useful!
References
Ward, B. (2014). How Linux Works: What Every Superuser Should Know (2nd ed.). No Starch Press. Pages 297-299
To connect to a remote host (remote computer), use ssh. (Shotts, 2019) ssh will allow you to use the command line as if you were physically present on the other computer’s Terminal. The computer you are connecting to needs to run ssh server and you need to be running ssh client.
if you want to connect with a different username other than the username on your local machine.
Note: You most likely won’t be using this if you are a desktop user, but if you are a programmer, you will most likely at least sometimes be required to connect to a machine remotely.
Thank you for reading!
References
Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Pages 234-238
If you ever need to edit connections, you can use nmtui. It came preinstalled with my Debian 10. It allows you to set your IP, among other things. I used it only once, but if you want more information, (and you can assume what I will say next) Google will give it to you.
The traceroute command is used to see the route of a packet sent from your computer to the destination computer. (Shotts, 2019) Remember, packets are just small chunks of data sent over the computer network.
traceroute to www.google.com (172.217.16.100), 30 hops max, 60 byte packets
1 speedport.ip (192.168.1.1) 4.490 ms 5.863 ms 7.275 ms
2 172.27.99.1 (172.27.99.1) 12.774 ms 15.713 ms 18.709 ms
3 172.28.238.67 (172.28.238.67) 21.826 ms 25.468 ms 26.822 ms
4 hdr11-gut21.ip.t-com.hr (195.29.224.145) 30.081 ms 33.572 ms hdr11-gut21-2.ip.t-com.hr (195.29.225.121) 35.273 ms
5 gtr11-hdr11.ip.t-com.hr (195.29.3.46) 37.511 ms 40.042 ms 42.717 ms
6 72.14.204.128 (72.14.204.128) 51.135 ms 13.224 ms 13.562 ms
7 74.125.242.241 (74.125.242.241) 17.242 ms 74.125.242.225 (74.125.242.225) 19.994 ms 22.164 ms
8 72.14.239.195 (72.14.239.195) 23.811 ms 27.805 ms 72.14.239.201 (72.14.239.201) 32.334 ms
9 bud02s25-in-f4.1e100.net (172.217.16.100) 32.541 ms 33.624 ms 35.218 ms
We can see all of the points that my packets visited until it finally reached www.google.com. If you were to see asterisks (*) instead of concrete information in any of the steps, that means that the router (the part of the networking hardware that routes the packets) is configured not to give away identifying information. Here this is not the case.
Thank you for reading!
References
Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Pages 227-228
The ip command is used to display information about network interfaces (among other things). (Shotts, 2019) Your network interface is the hardware within your computer which allows it to communicate via a computer network.
Here is an example of the ip command:
mislav@mislavovo-racunalo:~$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
inet 192.168.1.3/24 brd 192.168.1.255 scope global dynamic noprefixroute wlp3s0
valid_lft 81396sec preferred_lft 81396sec
inet6 fe80::5ce3:3fee:50bf:4d6f/64 scope link noprefixroute
valid_lft forever preferred_lft forever
First note that I have 3 network interfaces – each start with numbers 1 to 3. Also note that, in their first line, they have the keyword state following the word UNKNOWN, UP or DOWN. UP means that the interface is currently enabled. If you want to know your IP address, look up the inet field of the interface (before the forward slash). My IP address is 192.168.1.3. This is my local IP address, not my global IP address. You can Google “how to find out my global IP address” if you ever need to find your global IP address.
A side note: The ifconfig command was used for the purpose of finding out your local IP address before, but now it has been depracated. I couldn’t have used it on my Debian 10.
Thank you for reading!
References
Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Pages 228-229
Today let’s talk about the very basics of computer networks.
First of all, let me say that the field of computer networks is very vast. I had 2 college courses dealing with computer networks and I feel like we barely scratched the surface of the topic. So what I will do is try to introduce you to all of the concepts in computer networks we will need to understand the commands that will follow and no more. I will also be relatively broad in my descriptions and will not nitpick the details; again, just enough knowledge to cover the later commands. Computer networks could warrant a post series in it of itself and I would have to do it after extensively reviewing the subject matter.
A computer network is consisted of layers. Each time you are sending some data over a network, your data has to pass through these layers in your computer, and, at the destination computer, it also has to pass through the same layers, but in reverse order.
Each layer has a different function and addresses different concerns. There is a layer we are particularly interested in, called the network (or the internet) layer. On this layer, each device connected to a network has its own unique IP (Internet Protocol) address. This enables network devices to communicate with each other – they address each other using IP addresses. When sending data over a computer network, that data is most likely chunked into little pieces. Each one of these pieces traveling on the computer network is called a packet. Packets travel through the nodes of the computer network until they reach its destination. Packets are forwarded by routers, a piece of network hardware that routes packets to where they should go in order to reach their destination.
There is a difference between IP addresses – there is your local IP address, which is what computers within your local network use and there is your global IP address, unique to you globally. Think of it like this – if someone in your house wants to talk to your computer via a computer network, it uses the local IP address. If, on the other hand, someone wants to talk to your computer outside of your house, they have to globally address you. The same way when a family member calls your name – you know they are calling you. However, if you are to receive a letter from the police station and someone uses your name, they will use your full name, or even some identification number unique to you, so you can be sure that they are addressing you.
I think we have all it takes to look at some of the most basic network commands. Let’s take a look at them in the following posts.