Ok, here's the *actual* code:

open (LOGFILE, "/var/log/tac_acc.log");
while (<LOGFILE>) {
  print
        if /$username/;
  #if (/$username/) {
   #print "<br>",$_;
#  }
}
[download]

Apologies for leaving the comments in there, but you can see what I've done and what you've suggested. They both falsely match against *everything* though, and print the whole log file.. Is there something I'm missing?