You need to account for the headers, which many (most?) csv files I've encountered have. So I guess something like this to skip the headers in the second file

You need to account for the headers, which many (most?) csv files I've encountered have. So I guess something like this to skip the headers in the second file (this also assumes that headers don't have line breaks): cp file1.csv combined.csv && tail -n+2 file2.csv >> combined.csv