UNIX for Dummies Questions & Answers

Hi new to all this so bear with me.

I have two lists. List A has the old names and some values for each of the names

e.g.
List A:

Code:

snpa 3.2
snpb -2
snpc 0

List B has old names and new names equivalent:

Code:

snpa rs1234
snpb rs2345
snpc re3456

Now I have over 50,000 lines in each and want it to end up as

Final list after join.

Code:

rs1234 3.2
rs2345 -2
rs3456 0

The code I have been using:

Code:

join fileA.txt filebB.txt | awk '{print $3 ,$2}' | sort -k1 > final_list.txt

But all I get is the first few lines rather the 50k lines I should get.

Why is it working but only for a small amount of the data?

Try:

Code:

join -11 -21 -o2.2,1.2 <(sort -k1 fileA.txt) <(sort -k1 fileB.txt) > final_list.txt

Genius!! Thanks so much

What is the difference? What is this line doing that the other wasn't?

Would be good to learn a bit as well as just have the solution.

Thanks once again.

join needs the files to be sorted. This is what <(sort -k1 fileA.txt) <(sort -k1 fileB.txt) is doing