Mar 132018

So I have two csv files that have a common key. gnu join by itself can produce lines of output for records which have a common key.

What I would love to have happen, however, is when I use the -a 1 -a 2 , the program produce -e's values for each field of the merged output for the missing line in the file.
In other words

File 1
a 1
b 3
c 4

File 2
a 2
c 6
d 5

joined together with -a 1 -a 2 -e'""' currently produces
a 1 2
b 3
c 4 6
d 5

but lines b and d should have 3 fields, not 2 fields….

Merging two csv files into one
Merging two csv files into one