AWK: go through the file twice, doing different tasks

Question

I am processing a fairly big collection of Tweets and I\'d like to obtain, for each tweet, its mentions (other user\'s names, prefixed with an @), if the mentio

Answer 1

The idiomatic way to process two separate files, or the same file twice in awk is like this:

awk 'NR==FNR{ 
    # fill associative array 
    next
}
{
    # use the array
}' file1 file2

The total record number NR is only equal to the record number for the current file FNR on the first file. next skips the second block for the first file. The second block is then processed for the second file. If file1 and file2 are the same file, then this passes through the file twice.