Well, if you are using mod_perl, you could install a handler for just about any stage in a request. See
the mod_perl guide
On the other hand, if you just want to be notified when the access log is updated, you might try something like:
open LOG,"</var/log/httpd/access_log" or die "Cannot open log file: $!
+";
seek LOG,0,2; # set to eof
while (1) {
while (<LOG>) {
print; # or do something else...
}
sleep 1; # this is 1 seconds, so not exactly realtime
seek(LOG, 0, 1); # reset eof flag
}
See also
perldoc -f seek