i have 2 text files as a.txt and b.txt containing single column data. I want to remove the identical data from both the files using bash script.

For e.g
a.txt contains data as below

a.b.c.com
c.d.e.com
f.g.h.com

and b.txt contains data as below

f.g.h.com
i.j.k.com

The output should be

a.b.c.com
c.d.e.com
i.j.k.com

I have tried with sort, uniq -u and so on.. But none of them gave me correct output.