How to check for previous occurence? 1

[LovecraftHP]

I'm new to AWK, but I was wondering if any of you might be able to help me with this:

I want to be able to check whether the value of a certain field (the field is the same for all the records) is different from any of the field values in previous records. So e.g., every record has 4 fields, and I want to be able to check the 3d field of every record, with the "3d fields" of the previous records.

I've been trying to solve it using arrays, but so far unsuccessfully.

 

[vgersh99]

nawk -f fields.awk field.txt

#------------- fields.awk
BEGIN {
field2check="3"
}

{
if (! ($field2check in arr))
arr[$field2check]=NR;
else
printf("WARNING [%d]: [%s] was last seen on line->[%d]\n", NR, $field2check, arr[$field2check]);

}

#------------- fields.txt
1 2 3 4
5 6 7 8
1 2 3 4
2 4 6 8
1 3 5 7
5 6 7 8 vlad
+----------------------------+
| #include<disclaimer.h> |
+----------------------------+

 

[LovecraftHP]

Thank you!