Echo Command with Practical Examples

echo command is built in shell command , which used to display the value of a variable or print a line of text.  Echo command plays a important role in building a shell script.

Synatx :

# echo [Options] [String]

The items in square brackets are optional. A string can be defined as  finite sequence of characters (like letters, numerals, symbols  punctuation marks).

When echo command is used without any options or strings, echo returns a blank line on the display screen followed by the command prompt on the subsequent line. This is because pressing the ENTER key is a signal to the system to start a new line, and thus echo repeats this signal.

Options :

  • -n     do not output the trailing newline
  • -e     enable interpretation of backslash escapes
  • -E     disable interpretation of backslash escapes (default)

If -e is in effect, the following sequences are recognized:

  • \\     backslash
  • \a     alert (BEL)
  • \b     backspace
  • \c     produce no further output
  • \e     escape
  • \f     form feed
  • \n     new line
  • \r     carriage return
  • \t     horizontal tab
  • \v     vertical tab
  • \0NNN  byte with octal value NNN (1 to 3 digits)
  • \xHH   byte with hexadecimal value HH (1 to 2 digits)
 Example :1  Display the value of System Defined Variables

Using the set command , we can list the system define variables and to print the vaule of these variables we can use echo command :

jack@localhost:~$ echo $USER
jack
jack@localhost:~$ echo $HOME
/home/jack

 

Example:2 Display the value of User defined Variables :
jack@nextstep4it:~$ var1=`date`
jack@nextstep4it:~$ echo "Today's date  time is : $var1"
Today's date  time is : Mon Jul 28 13:11:37 IST 2014

 

Example:3 Display the text String
jack@nextstep4it:~$ echo " Hi this echo command testing"
Hi this echo command testing

 

Example:4 Use of backspace in echo command
jack@nextstep4it:~$ echo -e "Ubuntu \bis \bthe \bbest \bDesktop \bOS"

Above Command will Print :
UbuntuisthebestDesktopOS

Example:5  Use of  tab space in echo command
nextstep4it@nextstep4it:~$ echo -e "Ubuntu \tis \tthe \tbest \tDesktop \tOS"

Above command will show below output :
Ubuntu          is         the      best     Desktop         OS

Example:6 Use of Vertical tab in echo Command
jack@nextstep4it:~$ echo -e "Ubuntu \vis \vthe \vbest \vDesktop \vOS"
Ubuntu 
       is 
              the 
                     best 
                            Desktop 
                                          OS

 

Example:7  Colored output of echo command

echo command can change the font style, background color of fonts and font colors. Escape sequence \033 can be used to alter font properties. -e option has to be used in order to the escape sequence be in effect. Some of escape codes are listed below :

[0m: Normal
[1m: Bold fonts
[2m: Font color changes to Purple
[4m: Underlined fonts
[7m: Invert foreground and background colors
[8m: Invisible fonts
[9m: Cross lined fonts
[30m: Font color changes to Grey
[31m: Font color changes to Red
[32m: Font color changes to Green
[33m: Font color changes to Brown
[34m: Font color changes to Blue
[35m: Font color changes to Violet
[36m: Font color changes to Sky Blue
[37m: Font color changes to Light Grey
[38m: Font color changes to Black
[40m: Background color changes to Black
[41m: Background color changes to Red
[42m: Background color changes to Green
[43m: Background color changes to Brown
[44m: Background color changes to Blue
[45m: Background color changes to Violet
[46m: Background color changes to Sky Blue
[47m: Background color changes to Light Grey

Below command will print the output in red color.

jack@nextstep4it:~$ echo -e "\033[31mMagic of Linux\033[0m"
Magic of Linux

 

Below Command will print “Magic of Linux” in bold style and red background color.

nextstep4it@nextstep4it:~$ echo -e "\033[1m\033[41mMagic of Linux\033[0m"
Magic of Linux

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