--log.

   --log.backtrace value                                                  ($GETH_LOG_BACKTRACE)
         Request a stack trace at a specific logging statement (e.g. "block.go:271")

   --log.compress                      (default: false)                   ($GETH_LOG_COMPRESS)
         Compress the log files

   --log.debug                         (default: false)                   ($GETH_LOG_DEBUG)
         Prepends log messages with call-site location (file and line number)

   --log.file value                                                       ($GETH_LOG_FILE)
         Write logs to a file

   --log.format value                                                     ($GETH_LOG_FORMAT)
         Log format to use (json|logfmt|terminal)

   --log.maxage value                  (default: 30)                      ($GETH_LOG_MAXAGE)
         Maximum number of days to retain a log file

   --log.maxbackups value              (default: 10)                      ($GETH_LOG_MAXBACKUPS)
         Maximum number of log files to retain

   --log.maxsize value                 (default: 100)                     ($GETH_LOG_MAXSIZE)
         Maximum size in MBs of a single log file

   --log.vmodule value                                                    ($GETH_LOG_VMODULE)
         Per-module verbosity: comma-separated list of <pattern>=<level> (e.g.
         eth/*=5,p2p=4)

• geth --help, geth --log.vmodule