UNIX for Dummies Questions & Answers

Howdy Folks,

I have a list that looks like this:
(file2.txt)

AAA
BBB
CCC
DDD

and there are 24 of these short words.

I am matching these patterns to another file with 755795 lines (file1.txt).

I have this code for matching:

Code:

awk -v f2=file2.txt '
    BEGIN {
        while( (getline<f2) > 0 )   # read and collect records from f2
        {
            key = $1;
            ki = kidx[key]++;        # track number of duplicate keys (0 based)
            k2rec[key,ki] = $0;      # save unique record by key and dup count
        }
        close( f2 );
    }

    {
        key = $1;
        for( i = 0; i < kidx[key]; i++ )          # for each duplicate of key
            printf( "%s\t%s\n", k2rec[key,i], $0 );   # print f2 record, followed by current f1 record
    }
' <file1.txt > output

In this form every line in file1 that is matched goes into the same output file. What I would like to do is change the code such that each of the patterns in file2.txt gets its own file. For example:

all of the lines in file1.txt that match AAA would go in AAA.txt while all of the lines matching BBB would go in BBB.txt.

I'm not exactly sure how to handle controlling the output.

Thanks guys, I appreciate your help.
Robert

Not tested:

Code:

printf( "%s\t%s\n", k2rec[key,i], $0) > k2rec[key,i]

It will at least get me started, thanks very much for your time.