apvsync.c:
  provides synchronization between listen.tcl (which produces volumes
  on disk) and archiver.pl (which consumes them).
  
logmonitor.c:
  writes its standard input to a file, reopening the file
  whenever it receives a certain signal.  The wrapper scripts
  pilot/archiver.sh and pilot/pilot.sh pipe the output of
  archiver.pl and pilot.tcl to logmonitor to write log files, so that
  newsyslog can signal logmonitor when rotating the log files.
