join 2 files and print each line even if they don't match

Question

I'm sure this is super simple but I can't think of a way to do it. I have File1 and File2 (below) and I need to join based off the letter in the alphabet, but also print out the lines that have no match.

File1:

a james
b mike
c joe
d john
e nick
f chris

File 2

a 10 20 30 40
b 11 12 13 14
d 20 30 40 50
f 15 16 17 18

I want the output file to say

a james 10 20 30 40
b mike 11 12 13 14
c joe
d john 20 30 40 50
e nick
f chris 15 16 17 18

I'm supposed to use one line only. I tried:

join file1 file2 > file3

but that didn't print the lines that don't have a match.

Answer 1

If you do join -a1 file1 file2 > file3 that will work because it makes it a left outer join. join on its own is an inner join.