Regex: Named Captures 

• Apply regex across a file:

while(<>) {
    m{
        ^\S+                                  # Client host/IP
        \s\S+                                 # Identd user
        \s\S+                                 # HTTP auth user
        \s\[.*?\]                             # Date/timestamp
        \s"GET\s(/\S*)\s[^"]*"                # URL path requested
        \s\d+                                 # HTTP status code
        \s\d+                                 # Bytes sent in body
        \s"\Q$site_root\E(/[^"]*)"            # Referring URL path
    }x or next;
    $tally{ "$2 => $1" }++;
}