Terminal (emulator)

The terminal itself is a physical device that allows inputting and receiving information from a computer. The most important thing is that it is not necessary for the processing of instructions and data to be carried out on the terminal itself.

Certainly, in today’s world, it is common to interact with the operating system in text mode. Well, in most cases, we will not refer to this meaning of terminal. In fact, the correct term refers to the so-called terminal emulators. These allow us to use text mode within a graphical user interface. This other class of terminals are merely applications that run and give us access to a shell. In fact, they usually allow multiple shell types to be used. This is the case, for example, of Windows Terminal. By default, we will be able to manage the following: Windows PowerShell, PowerShell, Command Prompt, Azure Cloud Shell, the multiple distributions we have installed in the Linux Subsystem (WSL), etc.

On the other hand, Windows Terminal is not the only Windows terminal emulator. Indeed, there are MobaXterm, Cmder, ConEmu and others. However, in the case of Unix-based systems (Linux, *BSD, macOS), the catalog of available terminals is multiplied to infinity. In fact, each desktop environment usually offers its own (Gnome Terminal in GNOME, Konsole in KDE, iTerm in macOS…). But it is also possible to install third-party alternatives for all tastes (Terminator, Alacritty, Guake, st…).

Each terminal emulator differs by offering its own graphical interfaces, functionalities, and configuration options. For example, keyboard shortcuts, font and background customization, clipboard management, etc.

Consola [Virtual]

Console is a term that is often used inconsistently. In fact, even more so than the other terms in this list. Additionally, multiple definitions are available on the Internet. In fact, the discrepancies start even in the origin of the word. For some, the old physical console is exactly the same as a physical terminal. On the other hand, others introduce certain nuances, considering the former as a subset of the latter.

What happens when we talk about virtual console? What happens when we talk about virtual console? Many sources consider it, also, synonymous with (terminal emulator.) However, it would be more correct to refer to it as a shell session. Let’s see, let’s suppose we open a terminal emulator and start typing commands directly. In that case, we are, effectively, using a terminal and a console.

On the other hand, suppose we open two tabs in the terminal emulator, whether they are from the same shell. In that case, we are already using two consoles. It can also happen that we subdivide a tab using tools such as a multiplexer (for example, Tmux), or functions such as split table of Windows Terminal. In such a case, the number of consoles will continue to multiply, even if we are only using a single terminal.

In addition, when using a Linux system, we always have several consoles open (although not visible). We are talking about the so-called ‘TTY’, which we can access with the keyboard shortcut Ctrl + Alt + function key (one per key). Part of them will be graphic consoles. However, the others will be text consoles, each running in parallel with the others. Additionally, all of them working outside our graphical environment, so we would not be using them from terminal emulators.

Shell

We have already mentioned, when talking about terminals, several examples of different shells that can be found in Windows. As with terminals, the number of shells in Unix systems multiplies. Certainly, Bash is usually installed as the default shell. However, it is possible to change it for different ones, such as the very popular Zsh. Remember that macOS ended up adopting it as a default shell. Other options include the emerging Fish, the old Ksh and Tcsh, or minority options such as Xonsh.

The function of the shell is to interpret the commands we enter. You might think that there can’t be much difference in how some commands are interpreted. However, there are many variables to watch out for. For example, the different syntax of the scripts, or aspects such as the possibility of creating aliases and defining variables. Also, the existence of syntax highlighting or auto-completion functions. Likewise, the way in which the system output is displayed on the screen. Well, all these elements can make the user experience vary significantly depending on which shell we use.

Command interpreter (or command line)

Every shell is a command interpreter. However, not every shell is a shell. A command interpreter (also called CLI), is any software that interacts with us through the input of text commands. Some CLIs run on top of a shell and are not intended to be a way to control the operating system. Instead, they aim to be just a very specific software or online service. Examples of this can be NPM, IPython, GitHub CLI, AWS CLI or our favorite SSH client. Very well, in this way we have made clear the differences between terminal, console, shell and command line. Bye!

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How to enable the Windows Subsystem for Linux

WSL is a feature that allows Windows 10 users to use the Bash of the available Linux distribution. In addition, WSL provides a Linux-compatible kernel interface developed by Microsoft. Also, we can have the typical Linux directories like Home or Bin in Windows and the Windows directories in Linux bash. But maybe the most relevant aspect is to be able to use Bash commands inside Windows without the need to resort to a virtual machine. Well, let’s see how to enable this system. In the first place, follow this path to enter the optional features of Windows. Control Panel>Programs>Turn windows features on or off

In the box below, scroll down to find Windows Subsystem for Linux. Please check the appropriate box.

Wait a few seconds while the features are installed. Then restart the computer to confirm the changes.

Download and Install Ubuntu 18.04 LTS

Once the configuration is enabled, just go to the Windows Store and download the available distro. At the moment the following options are ready for download: Ubuntu, Kali, Open Suse Leap 15-1, Debian and Alpine WSL. Undoubtedly in the future more will be added. Well, this time we will use Ubuntu 18.04 LTS. You can download it from this link. Press Get and wait while the program downloads.

Once the download is complete, you can launch the program from the same store. Or you can also type Ubuntu from the Windows search engine. Please wait a few moments while the installation is completed. Then assign any user name and add a password.

Using Ubuntu for the first time

Once the preparations have been made, it’s time to test the operation of Ubuntu. With this intention, update the list of packages in the repositories by running the following command:

 sudo apt-get update 

Then type the password and press enter. Immediately the ubuntu bash will start working.

Well, finally we’ve seen how to install and use bash in Windows 10. From this moment on, just type Ubuntu in the search bar to launch the app. Before I say goodbye, I invite you to see our post about Microsoft employees infected with COVID-19. Bye

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youtube-dl allows a user to download video and audio (or split the audio/video into separate files) from YouTube links by simply pasting the shared URL into the terminal console following the youtube-dl syntax. That’s the easy part. But what do you do if you have more than one or two links?

Sometimes when I am browsing YouTube I collect a bunch of links which I want to download. Sometimes this can be 3-5 links, or sometimes I can end up with an extensive list of 10 or more which I had not originally intended. It can be time consuming manually pasting in links then waiting for each download to complete before pasting in the next link and repeating the process. Thankfully, there is an easier way to do it by writing a neat little Bash script.

Let’s get started.

For example purposes, we will use the following fake randomly generated links to download:

https://youtu.be/ACcLsrbigWu
https://youtu.be/BAbg6BnkB3F
https://youtu.be/l0eRloaKxVS

So let’s write ourselves a neat little Bash script to deal with these links, using a combination of Bash and youtube-dl.

I use Emacs for this kind of short-style scripting, but feel free to use whatever code editor you prefer. Let’s just call our script something easy, like “yt-queue.sh”:

> emacs yt-queue.sh

Then in your code editor, enter the following syntax:

#!/bin/bash
#

#start
#links
#end

This provides a basic and sensible script layout for your youtube-dl queue.

Where we have “#links”, press “ENTER” at the end of the line so we get a new blank line. Now we need to paste in the links to download. But remember to write “youtube-dl” before each link. This is effectively telling the Bash script to use youtube-dl to download the link that follows. Once one link has completed downloading, the script then passes onto the next line in the queue, and then the next and so forth. Stupidly simple, yet effective.

After pasting in the links, the script should look something like this:

#!/bin/bash
#

#start
#links
youtube-dl https://youtu.be/ACcLsrbigWu
youtube-dl https://youtu.be/BAbg6BnkB3F
youtube-dl https://youtu.be/l0eRloaKxVS
#end

The script is finished. Now we need to just execute it when we are ready to start it.

This process is particularly useful for downloading extensive lists which can be done overnight – write your script before you go to bed, execute the script and by the morning your files will be completed.

Execute the script by simply running the following:

> bash yt-queue.sh

You have now learned how to write a simple Bash script to queue links for youtube-dl.

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In the case of Bash – the most popular shell for Linux, auto code completion isn’t available by default. Bash can run most of the “sh” scripts without any modification. Code auto-completion is a great feature for reducing your load of typing each and every single command as you type. If you’re interested in the code completion, then Fish shell is the best choice.

Despite default code completion, you can still enjoy the feature, thanks to the great “bash-completion”. This tool will enable the auto-completion feature on Bash shell.

Let’s enjoy “bash-completion” shell right away!

Getting “bash-completion”

The “bash-completion” provides all the available pre-built packages for the major Linux distros. Check bash-completion on GitHub.

The following guide will install “bash-completion” from source and it will apply for all the Linux distros.

Grab “bash-completion” –

git clone https://github.com/scop/bash-completion.git

cd bash-completion/

Build the tool –

autoreconf -i

./configure

make

make check

At this stage, you may find out some dependency issue. For passing this stage, “pytest” >= 3.6, pexpect, tcllib and dejagnu.

Install “bash-completion” –

sudo make install

Using “bash-completion”

It’s actually a bash script by itself. Check out the code of “bash-completion” –

bat /etc/profile.d/bash_completion.sh

After the installation is complete, it’s time to enjoy auto code completion. Fire up a terminal –

sudo apt i[TAB]

cat /etc/re[TAB]

You can also set your simple bash completion code. The method follows the following structure –

complete -W ‘<autocompletion_codes>’ <command_name>

Let’s see with an example.

complete -W ‘google.com osradar.com’ host

In the above command, there will be 2 different autocomplete suggestions for “host” (google.com and osradar.com).

Type “host” command –

host [TAB]

host google.com

host osradar.com

Enjoy!

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Today, let’s grab and enjoy the C Shell – the shell using the C++ syntax instead of the popular and familiar “bash” syntax. It’s an old shell. However, the shell gets much love from the Unix community, especially the programmers.

For enjoying C Shell, you have to get the Tcsh – a modified version of the original C Shell with new features and enhancements.

Let’s get C Shell right away!

Installing C Shell (Tcsh)

C Shell is a very cool shell and a nice alternative to the default Bash shell. However, almost all the Linux distros don’t set C Shell by default. You have to install it and set it as the default shell manually.

Run the following command(s) according to your own Linux distro –

• Ubuntu

sudo apt install tcsh

• Debian

sudo apt-get install tcsh

• Fedora

sudo dnf install tcsh

• OpenSUSE

sudo zypper install tcsh

• Arch Linux

sudo pacman -S tcsh

• Other Linux distros

If your system wasn’t listed above, you have to manually find out the package for your system. The package should be named as “tsch” or “c shell”. Tcsh has been around for quite a long time, so your chance of finding out C Shell is pretty high.

Listing all the shells

Before we switch to the new C Shell, we have to know the location of the shell(s). Run the following command –

cat /etc/shells/

In most cases, you’ll get more than one available shells in your system. Run the following command for the “tcsh” only.

cat /etc/shells | grep tcsh

It’s time to shift towards Tcsh.

chsh

Now, when asked about “Login shell”, enter “/bin/tcsh” (without quotes).

Voila! C Shell is your default shell now!

Reverting back to Bash

Not interested in C Shell anymore? Run the following command for reverting back to Bash –

chsh

Enter the value –

/bin/bash

Voila! Bash is back!

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Let’s switch from Bash to ZSH.

Installing ZSH

ZSH is one of the most popular alternatives to the Bash shell. That’s why it’s available in almost all the Linux distro repositories. You shouldn’t have any problem getting it into your system. Run the following command(s) according to your system.

• Ubuntu

sudo apt install zsh -y

• Debian

sudo apt-get install zsh -y

• Fedora

sudo dnf install zsh

• OpenSUSE

sudo zypper install zsh

• Arch Linux

Arch Linux uses ZSH by default. However, run the program for making sure that it does, in case you switched to Bash.

sudo pacman -S zsh

• Other Linux distros

For other distros, you have to have “ncurses-devel” and “g++” installed in your system. Find those out for your Linux distro and install those.

Then, download the latest ZSH archive from SourceForge.

Now, run the following commands:

# Running all the commands as sudo
sudo -s

cd ~/Downloads
tar -vxzf zsh-5.5.1.tar.gz
cd zsh-5.5.1

./configure
make
make check
make install

Configuring ZSH

Now, let’s start configuring ZSH. At first, run the program from the terminal to open up the configuration wizard.

zsh

From the opened up window, press 1.

There are more options to choose from. As we’re configuring the shell completely new, hit 1 again.

From here, press 1 for setting the line-size of history, press 2 for creating the new history file and press 3 for customizing the number of lines to save.

Then, press “q” to return back to the main menu.

Press 2 for setting up the auto-complete system. From there, press 1.

Now, everything is about to complete. If you’re an advanced user, you can surf through the options and make more changes as you like. After everything is complete, press 0 for saving the changes and exiting the shell.

Changing default shell

Now, ZSH is ready to use. However, it isn’t the default shell solution that terminal will load every time. For solving the issue, run the following commands:

sudo -s
which zsh
chsh -s /usr/bin/zsh

Now, reboot your system.

Voila! Your system is running ZSH. For having more customizability with your ZSH shell, you should install Oh My ZSH. It’s a lightweight and powerful tool for customizing ZSH. Here is all the usage of the tool.

You can even show asterisks when you type the password for “sudo”.

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