echo

Description

echo is a standard Unix utility that displays a line of text in the terminal.

The command syntax is:

echo [flags] [text]

Flags

Here are some flags associated with echo.

• -e: enable interpretation of backslash escapes.
• -E: disable interpretation of backslash escapes.
• -n: do not output the trailing newline.
• --help: get more information about the command

-e

Description:

With the -e option, the echo command will interpret escape characters such as \t and \n.

Usage: Let us assume we want to display the word Hello World into the terminal such that the words are separated by a tab. We will do this as:

echo -e "Hello\tWorld"

Since -e is the default flag, we can omit it and still get the same result.

echo "Hello\tWorld"

Output:

Hello   World

-E

Description:

With the -E option, the echo command will interpret escape characters such as \t and \n as characters and not escape characters.

Usage: Taking above example with -E flag:

echo -E "Hello\tWorld"

Output:

Hello\tWorld

-n

Description:

With the -n option, the echo command will not output the trailing new line. This is useful for when you're writing multiple echo statements in a script as described in the example section.

Usage:

echo -n "Hello World"

Output:

Hello World

--help

Description:

With the --help option, the echo command will show other flags and options for the command that are not commonly used.

Usage:

echo --help

Examples

1. Let's say you are writing a shell script that displays a progress message with a series of dots to indicate a task is in progress. You want the dots to appear on the same line, without a newline character between them.

   Without -n flag: Assume the contents of a test file are as follows:

    echo "Task in progress"
    echo "..."
   

   Executing the file, the output will be:

    Task in progress
    ...
   

   With -n flag: Assume the contents of a test file are as follows:

    echo -n "Task in progress"
    echo "..."
   

   Executing the file, the output will be:

    Task in progress...
   

2. Printing words in a separate line

    echo -e "Hello\nWorld"
   

   The output will be:

    Hello
    World
   

3. Printing the escape characters as is:

    echo -E "Hello\nWorld"
   

   The output will be:

    Hello\nWorld
   

Additional Information

echo command is frequently used to redirect user input to a file such as:

echo "Save this file" > file.txt

Now the content of file.txt will be:

Save this file

Exercises

1. Use the --help flag and print a \ into the terminal.

2. Create a file with your name with the echo command and the > redirect operator.

3. Create a file with two lines Hello and World using a single echo command and the > redirect operator.