Logging options are set as section,level where each source file
is assigned a unique section. Lower levels result in less
output, Full debugging (level 9) can result in a very large
log file, so be careful.
The magic word "ALL" sets debugging levels for all sections.
The default is to run with "ALL,1" to record important warnings.
The rotate=N option can be used to keep more or less of these logs
than would otherwise be kept by logfile_rotate.
For most uses a single log should be enough to monitor current
events affecting Squid.