[SOLVED] Merge two files using AWK with conditions

Issue

I am new to bash scripting and need help with below Question. I parsed a log file to get below and now stuck on later part. I have a file1.csv with content as:

mac-test-1,10.32.9.12,15
mac-test-2,10.32.9.13,10
mac-test-3,10.32.9.14,11
mac-test-4,10.32.9.15,13

and second file2.csv has below content:

mac-test-3,10.32.9.14
mac-test-4,10.32.9.15

I want to do a file comparison and if the line in second file matches any line in first file then change the content of file 1 as below:

mac-test-1,10.32.9.12, 15, no match
mac-test-2,10.32.9.13, 10, no match
mac-test-3,10.32.9.14, 11, matched
mac-test-4,10.32.9.15, 13, matched

I tried this

awk -F "," 'NR==FNR{a[$1]; next} $1 in a {print $0",""matched"}' file2.csv file1.csv 

but it prints below and doesn't include the not matching records

mac-test-3,10.32.9.14,11,matched 
mac-test-4,10.32.9.15,13,matched

Also, in some cases the file2 can be empty so the result should be like this:

 mac-test-1,10.32.9.12,15, no match
 mac-test-2,10.32.9.13,10, no match
 mac-test-3,10.32.9.14,11, no match
 mac-test-4,10.32.9.15,13, no match

Solution

You are not printing the else case:

awk -F "," 'NR==FNR{a[$1]; next}
{
 if ($1 in a) {
  print $0 ",matched"
 } else {
  print $0 ",no match"
 }
}' file2.csv file1.csv

Output

mac-test-1,10.32.9.12,15,no match
mac-test-2,10.32.9.13,10,no match
mac-test-3,10.32.9.14,11,matched
mac-test-4,10.32.9.15,13,matched

Or in short, without manually printing the comma but using OFS:

awk 'BEGIN{FS=OFS=","} NR==FNR{a[$1];next}{ print $0 OFS (($1 in a)?"":"no")"match"}' file2.csv file1.csv

Edit

I found a solution on this page handling FNR==NR on an empty file.

When file2.csv is empty, all output lines will be:

mac-test-1,10.32.9.12,15,no match

Example

awk -F "," '
ARGV[1] == FILENAME{a[$1];next}
{
 if ($1 in a) {
  print $0 ",matched"
 } else {
  print $0 ",no match"
 }
}' file2.csv file1.csv

Answered By - The fourth bird

Answer Checked By - Mildred Charles (WPSolving Admin)