Copy contents of a file
You can run the shell command /usr/bin/textutil  in the Terminal.app found in /Applications/Utilities/ 

textutils  Can be used to convert the text from one format to another.

But it also can  "Read the specified files, concatenate them, and write the result out as a single file in the indicated format."

/usr/bin/textutil file/s -cat convert to format -output file output path

It will concatenate differently formatted files.

The formats textutils can read and write to are

txt, html, rtf, rtfd, doc, docx, wordml, odt, or webarchive

Example

/usr/bin/textutil foo1.txt foo2.txt foo1.rtf foo.html -cat txt -output /file/path/foo.txt