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echo
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echo simply prints the words (parameters) that follow the command. it is
surprisingly useful tool.

$ echo hello
hello

$echo Hello my name is   Kity
Hello, my name is Kitty          #notice the even spacing between the words

$ echo "Hello my name is   Kitty"
Hello, my name is      Kitty        #the non equal spaces are preserved (due to the quotes)

The following characters have special meaning:
        # all characters to the right are commented out
        ; this marks the end of the current command
        $ by itself is fine  but not if succeeded alphanumeric+underscore
        * fine if followed or succeeded by any character
        * by iteself expands to the list of files in the current directory
You can escape these  characters by "\"

	# arcane use of echo
$ echo *	#lists all files in the directory, separated by a blank
		# but does not expand the sub-directories 
$ echo *.txt    # lists all .txt file on a single line, separated by a blank

In contrast, 
$ ls -m         #lists all files in the directory, separated by a comma
		# but does not expand the sub-directories
$ ls -m *       #lists all files, including those in sub-directories, comma
		# separated
		#NOTE: the list can include \nl (nasty)

flags: -n or -e
  -n   the string is printed without carriage return
  -o   ASCII control characters such as \a (for bell), \b (for move back)
       are active 

$ echo -n "Hello Kitty"  #will not print carriage return
$ echo -n "Hello Kitty"; echo " from Japan"  


$ echo -e "Hello Kitty. Long time no see \a"   #you should hear ASCII bell