Echo is popular command comes with all of the Linux distributions. Echo is provided by bash and C shells. Echo simple outputs given values to the console or terminal.
Man Echo
To get more detailed help and echo official documentation use following command
1 | $ man echo |
Syntax
Echo command provides two type of syntax like below.
1 | echo [SHORT-OPTION]... [STRING]... |
OR
1 | echo LONG-OPTION |
Display Text
Simple and most common usage of echo command is just printing specified text to the standard output like below.
1 | $ echo Poftut is very useful |
Print Variables
Other popular usage form is printing shell variables like below.
1 | $ echo My terminal is $TERM |
Remove Spaces While Printing
There is -e option which will remove all spaces by using back spaces defined with \b while printing text
1 | $ echo -e "This \bis \bpoftut" |
Bash Echo New Line
Another useful usage is adding \n control character which will print new line.
1 | $ echo -e "This \nis \npoftut" |
Tab
While printing some text to the standard output tabs can be placed in to this text by using \t
1 | $ echo -e "This \tis \tpoftut" |
Vertical Tab
Vertical tab will provide new line and align the output text like below.
1 | $ echo -e "This \vis \vpoftut" |
Carriage Return
Carriage return will delete previous part of the text and only print after last carriage return with \r
1 | $ echo -e "This \ris \rpoftut" |
Backspace
Backspace control character will delete single character to the backward with \b in the text.
1 | $ echo -e "This \bis \bpoftut" |
Omit New Line
Normally after printing text to the standard output new line is provided to make things more clear. But this new line can be prevented with option -n
1 | $ echo -e -n "This is poftut" |
Alert
Alert can provided to the shell subsystem with \a . This is very useful to make shell scripts and application more interactive
1 | $ echo -e "This is poftut\a" |
This option will not effect to the output of the text.
Print All Files and Folders
Echo command can work with bash features easily. To easily and simply print all files and folders of the current directory following command can be used.
1 | $ echo * |
Print specific Extension Files
While printing files and folders specific extensions can be used to filter output. For example we want to print to the standard output only c source files with extension .c
1 | $ echo *.c |
Write Into File
Without opening any text editor some text can be written to a file. The file must not be preexist. If file is all ready exist all content is deleted and given text is written to the text file.
1 | $ echo "This is poftut" > mystory.txt |
Create Empty File
Empty file can be create by providing empty string definition and redirecting this to a file.
1 | $ echo "" > empty_file.txt |
Add To The File
Last example about the echo command is adding more text to the existing file. Adding operation will no delete existing text in the file.
1 | $ echo "This is poftut" >> mystory.txt |
