Linux command to copy contents of one file to another by using 2 ways

How to copy content of one file to another in linux is shown

#linuxtutorial

[gsekar]

Hi suggest, i have multiple files with same header so i want merge all files into single file with only one header

[Chalisque]

cat source_file | grep . | rev | rev | sed -e "s/a/a/g" | dd if=/dev/stdin of=target_file