$cmd = qq{cat <<-ENDOFMESSAGE \none \ntwo \nthree \nENDOFMESSAGE};  
print ($cmd =~ s/\n/\\n/gr);
print "\n";
# cat <<-ENDOFMESSAGE \none \ntwo \nthree \nENDOFMESSAGE
print `$cmd`;
# one 
# two 
# three