File1 + (File2 - first line) > File3

Question

I have two csv/text files that I'd like to join. Both contain the same first line. I'm trying to figure out how to use sed and cat to produce a merged file, but with only one copy of the first line. And I'm having a time with syntax. Any help would be greatly appreciated :-D! Thanks, Andrew

Answer 1

Another option with awk:

awk 'NR==FNR || FNR>1' file1.txt file2.txt .. fileN.txt

This prints all lines in the first file, OR any line in subsequent files after the first line.

Answer 2

This will combine files data1.txt and data2.txt in file merged.txt, skipping the first line from data2.txt. It uses awk if you are ok with it:

(cat data1.txt; awk 'NR>1' data2.txt) > merged.txt

awk appends all lines with line number > 1 from file data2.txt to file merged.txt.

NR is a built-in awk variable that stands for the current line number of the file being processed. If the Boolean expression NR > 1 is true, awk prints the line implicitly.

If you didn't care about keeping data1.txt intact, you could just append your 2nd file (minus its first line) and reduce to just this:

awk 'NR>1' data2.txt >> data1.txt

Answer 3

I'd say the most straightforward solution is:

( cat file1.txt ; tail -n +2 file2.txt ) > file3.txt

It has the advantage of stating clearly just what you're doing: print the entire first file, then print all but the first line of the second file, writing the output to the third file.