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Help to understand multi-line

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# 1  
Old 10-08-2012
Help to understand multi-line
This code
Code:
cat <<'EOF'
Red
Green
Blue
EOF

gives output to screen
Code:
Red
Green
Blue

Same output as
Code:
echo "Red"
echo "Green"
echo "Blue"

I do not understand why cat gives same output as echo
I do understand example above runs the command line by line until it find the tag EOF used as start from cat <<'EOF'

I am used to use cat as list output of file.

Also some more information on how multi line works. (a google for << does give nothing)
# 2  
Old 10-08-2012
Try searching for "here document" instead.

Anyway, cat is reading from standard in (STDIN) and displaying the text line by line. Just like this:

Code:
$ echo hello | cat
hello
$

You are just telling cat to take STDIN a line at a time from the "here document".

For the fun of it, just type cat without any arguments and press enter. Now type something. It will be repeated to STDOUT.
Last edited by gary_w; 10-08-2012 at 03:17 PM..
This User Gave Thanks to gary_w For This Post:
Jotne
# 3  
Old 10-08-2012
In these examples the cat and echo give the same output but do not work the same. cat contatenates files and prints to standard output. In the example, cat is followed by << which is redirection operator. cat will concatenate all text until the closing label is found. In this case the EOF. echo displays a line of text to standard output.
This User Gave Thanks to rdrtx1 For This Post:
Jotne
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