How to cat multiline content into a file with shell

Sometimes we want to copy a paragraph then paste into or append into a file.

We can use a text editor, such as vi to do the copy paste.

It will be convenient to do it in command line with just cat and >.

Here is the example, the normal way is echo some thing followed by >. 

In case of multi-line, we need to use <<EOF to mark the end of the file.

EOF won't be a literal string that enters the final result, it is the marker of End Of File instead.

here is the example code:

demo>cat > demo.txt <<EOF

> adfd

> dfadfad

> adfafa

> EOF

demo>cat demo.txt

adfd

dfadfad

adfafa

demo>

The file content is now get updated with your strings.