Bash scripts are very popular and one of the simplest scripting languages. As with any programming or scripting language, you will sometimes output text to the terminal. This can happen in many scenarios, for example, when you want to print the contents of a file or check the value of a variable. Programmers also debug their applications by printing the values of their variables to the console. Before we get into Bash scripting, which will be another tutorial, let's look at the various ways we can output text in the terminal.
Echo is the most important command you need to know to output text to the terminal. As the name implies, Echo prints numbers or strings to the standard output of the terminal. It also has a number of options, which are listed in the following table.
| Options | Definition |
| -n | Do not print the trailing newline |
| -E | Disable interpretation of back-slash escaped characters |
| -e | Enable interpretation of backslash escapes |
| \a | Alert |
| \b | Backspace |
| \c | Suppress trailing newline |
| \e | Escape |
| \f | Form feed |
| \\ | backslash |
| \n | New line |
| \r | Carriage return |
| \t | Horizontal tab |
| \v | Vertical tab |
According to the Linux documentation, the following is the syntax for echo command.
echo [option(s)][string(s)]
Now, we shall see the different ways in which we can output the text on the terminal.
Send Text to Standard Output
To output any string or number or text on the terminal, type the following command and press enter.
echo "Hello World"
The following output will be shown on the terminal
Print a Variable
Let’s declare a variable and prints its value on the terminal. Suppose x is a variable which we have initialized at 100.
x=100
Now, we will output the value of the variable on the terminal.
echo x
100 will be printed on the terminal. Likewise, you can also store a string in a variable and output it on the terminal.
Try it out and let us know if it was easy for you.
Remove Space between Words
This is one of my favorite options of the echo command as it removes all the space between different words in the sentences and jumbles them up together. In this feature, we will be using two of the options as mentioned in Table 1.
echo -e "Hello \bmy \bname \bis \bjohn \bDoe"
As you can see from the above example, we are enabling the interpretation of backslash escapes as well as adding backspace. The following output was shown.
Output Word in New Line
This option of echo comes in really handy when you are working with bash scripting. Mostly you need to move to the next line once you are done. Therefore, this is the best option to use for that.
echo -e "Hello \nmy \nname \nis \nJohn \nDoe"
The output will display each word in a separate line as shown in the screenshot below.
Output Text with Sound
This is a simple option of outputting text with a bell or alert. To do this, type the following command.
echo -e "Hello \amy name is John Doe"
Make sure that your system’s volume is high enough for you to hear the tiny bell that sounds when the text is outputted on the terminal.
Remove Trailing New Line
Another option of the echo is to remove the trailing newline so that everything outputs on the same line. For this, we use “\c” option as shown in the figure below.
echo -e "Hello my name \cis John Doe"
The following output is shown
Add a Carriage Return to the output
To add a specific carriage return in your output, we have “\r” option for this.
echo -e "Hello my name \ris John Doe"
The following output is shown to you on the terminal.
Use Tabs in Output
While printing output on the terminal, you can add horizontal and vertical tabs as well. These come in handy for cleaner outputs. To add horizontal tabs, you have to add “\t” and for vertical tabs, add “\v”. We will be doing a sample for each of these and then a combined one.
echo -e "Hello my name \tis John Doe"
The output for this command will be shown as follows
echo -e "Hello my name \vis John Doe"
The output for this command will be shown as follows
Now we will combine this example for a set of sentences we have.
echo -e "Hello my name \vis John Doe. Hello! My name is \tJane Doe"
The following will be printed on the terminal.
These are all options that can be used to print text in a terminal. This is an important feature to learn because it will help you when you start working on bash scripts. Make sure you use each of the options and practice diligently. Let us know if this tutorial helped you solve a problem.