UNIX for Dummies Questions & Answers

Hi,

I have two files that I would like to merge and think that there should be a solution using awk. The files look something like this:

file 1
IDX1 IDY1
IDX2 IDY2
IDX3 IDY3

file 2
IDY1 dataA data1
IDY2 dataB data2
IDY3 dataC data3

Desired output
IDX1 IDY1 dataA data1
IDX2 IDY2 dataB data2
IDX3 IDY3 dataC data3

My problem is that in file 2, some of the IDY's are repeated, whereas in file 1 they are not. I would like to keep the repeated entries in file 2 and link the second ID name from file 1.

Hope this makes sense. Thanks in advance for the help!

No need for AWK here:

Code:

join -t" " -12 -21 -o1.1,1.2,2.2,2.3 file1 file2

This should match the last of IDY entries in file2

Code:

awk 'NR==FNR{A[$1]=$0;next}$2=A[$2]' file2 file1

Thanks for this. It did join the files but only seemed to find the first entry for IDY in file 2, so file is the length of file 1. File 1 is ~400 lines and file 2 is ~3,000 lines with multiple lines for the same IDY. I'd like to preserve the length of file 2 but add on the extra ID code from file 1.

But thanks for the start!

OK, now I think I understand what you mean (I thought you meant the other way around)
Try:

Code:

awk 'NR==FNR{A[$2]=$0;next}$1=A[$1]' file1 file2

Works beautifully! Thanks so much!

BTW, couldn't get the join command to work. It returned an empty output. I'll look into it more.