10.4) Overwrite And Append
You need to do one of two things to deal with this file already in existence. You can either overwrite the contents of file3 with the new results by putting an ‘!’ after the ‘>’, as below:
paste file1 file2 >! file3
Or you can keep the contents of file3 and append the new results to it with and extra ‘>’, as below:
paste file1 file2 >> file3